ni-motion™ help · help you develop ni-motion applications. this help file is intended for...

NI-Motion™HelpJuly2007,372134B-01ThishelpfileprovidesinformationabouttheNI-Motiondriversoftware,includingbackground,configuration,andprogramminginformation.ThepurposeofthishelpfileistoprovideabasicunderstandingoftheNI-Motiondriversoftware,andprovideprogrammingstepsandexamplestohelpyoudevelopNI-Motionapplications.ThishelpfileisintendedforexperiencedLabVIEW,C/C++,orotherdevelopers.Codeinstructionsandexamplesassumeaworkingknowledgeofthegivenprogramminglanguage.Thishelpfilealsoassumesageneralknowledgeofmotioncontrolterminologyanddevelopmentrequirements.ThishelpfilepertainstoallNImotioncontrollersthatusetheNI-Motiondriversoftware.Formoreinformationaboutthishelpfile,refertothefollowingtopics:UsingHelpRelatedDocumentationGlossaryImportantInformationTechnicalSupportandProfessionalServicesTocommentonNationalInstrumentsdocumentation,refertotheNationalInstrumentsWebsite.©2007NationalInstrumentsCorporation.Allrightsreserved.

RelatedDocumentationMostmotioncontrolmanualsalsoareavailableasPDFs.YoumusthaveAdobeReaderwithSearchandAccessibility5.0.5orlaterinstalledtoviewthePDFs.RefertotheAdobeSystemsIncorporatedWebsiteatwww.adobe.comtodownloadAdobeReader.RefertotheNationalInstrumentsProductManualsLibraryatni.com/manualsforupdateddocumentationresources.Thefollowingdocumentscontaininformationthatyoumayfindhelpfulasyouusethishelpfile:

GettingStartedwithNI-MotionforNI73xxMotionControllers—ProvidesinstallationinstructionsandgeneralinformationabouttheNI-Motionproduct.GettingStarted:NISoftMotionControllerforCopleyControlsCANopenDrives—ContainsinformationaboutgettingstartedwiththeNISoftMotionControllerforCANopen.NI-MotionVIHelp—ContainsLabVIEWVIreferencefilesandprovidesdetailsabouteachVI,includingVIdescriptions,listsofcontrolandinputterminals,usage,illustrations,anderrorcodes.NI-MotionFunctionHelp—ContainsfunctionreferencefilesforCandVisualBasicandprovidesdetailsabouteachfunction,includingadescriptionofthefunction,alistofthefunctionparameters,illustrations,anderrorcodes.Measurement&AutomationExplorerHelpforMotion—ProvidesinformationaboutusingMAXtoconfiguretheNI73xxmotioncontrolleraswellassomeadvancedconceptualinformationabouttopicssuchasBodeanalysisandcontrolloopparameters.NI73xxusermanuals—DescribestheelectricalandmechanicalaspectsoftheNI73xxmotioncontroller,andcontainsinformationaboutinstallingandoperatingthedevice.NI-MotionReadme—Containssystemrequirements,installationinstructions,descriptionsofanychangesmadetothesoftware,informationaboutnewfeaturesintherelease,andinformationaboutlate-breakingknownissuesthatarenotdocumentedinotherNI-Motiondocuments.NIDeveloperZone(NIDZ)—VisittheNIDeveloperZone,atni.com/zone,forexampleprograms,tutorials,technical

NI-MotionCReferenceHelp.chm::/NI-Motion_Function_Help.html

presentations,theInstrumentDriverNetwork,productadvisors,applicationnotes,andadiscussionforumwhereyoucanshareideas,questions,andsourcecodewithmotiondevelopersaroundtheworld.MotionHardwareAdvisor—VisittheNationalInstrumentsMotionHardwareAdvisoratni.com/devzone/advisors/motion/toselectmotorsandstagesappropriatetothemotioncontrolapplication.

InadditiontotheNIDeveloperZone,youcanfindNI-MotionC/C++andVisualBasicprogrammingexamplesintheNI-Motion\FlexMotion\ExamplesfolderwhereyouinstalledNI-Motion.ThedefaultdirectoryisProgramFiles\NationalInstruments\NI-MotionforWindowsXP/2000andthe32-bitversionofWindowsVistaandProgramFiles(x86)\NationalInstruments\NI-Motionforthe64-bitversionofWindowsVista.YoucanfindLabVIEWexampleprogramsunderexamples\MotioninthedirectorywhereyouinstalledLabVIEW.YoucanfindLabWindows™/CVI™examplesundersamples\MotioninthedirectorywhereyouinstalledLabWindows/CVI.YoucanfindtheNI-MotionC/C++andLabVIEWexamplecodereferencedinthismanualintheNI-Motion\Documentation\Examples\NI-MotionUserManualfolderwhereyouinstalledNI-Motion.

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IntroductionThissectionprovidesbasicinformationabouttheNI-Motiondriversoftware,motioncontrolsetup,andspecifictask-basedinstructionsforcreatingmotioncontrolapplicationsusingtheLabVIEWandC/C++applicationdevelopmentenvironments.

AboutNI-MotionNI-MotionisthedriversoftwareforNationalInstruments73xxmotioncontrollersandtheNISoftMotionController.YoucanuseNI-MotiontocreatemotioncontrolapplicationsusingtheincludedlibraryofLabVIEWVIsandC/C++functions.NationalInstrumentsalsoofferstheNIMotionAssistantandNI-MotiondevelopmenttoolsforVisualBasic.

NI-MotionArchitectureTheNI-MotiondriversoftwarearchitectureisbasedontheinteractionbetweentheNImotioncontrollersandahostcomputer.ThisinteractionincludesthehardwareandsoftwareinterfaceandthephysicalandfunctionalarchitectureoftheNImotioncontrollers.ThefollowingblockdiagramdemonstratestheNImotioncontrolhardwareandsoftwareinteraction.

NoteTheNIMotionControllerblockisnotapplicabletotheNISoftMotionController.

NIMotionControllerArchitectureFunctionally,thearchitectureoftheNI73xxmotioncontrollersandtheNISoftMotionControllerisgenerallydividedintofourcomponents:supervisorycontrol,trajectorygenerator,controlloop,andmotionI/O.FortheNISoftMotionController,themotionI/Ocomponentisseparatefromthecontroller.Thefollowingfiguresdemonstratehowthecomponentsofthe73xxandNISoftMotionControllerinteract.TypicalNI73xxMotionControllerFunctionalArchitecture

NISoftMotionControllerFunctionalArchitecture

NIMotionControllerFunctionalComponentsThefollowinglistdescribeshoweachcomponentofthe73xxcontrollersandtheNISoftMotionControllerfunctions:

Supervisorycontrol—Performsallthecommandsequencingandcoordinationrequiredtocarryoutthespecifiedoperation

Systeminitialization,whichincludeshomingtoazeropositionEventhandling,whichincludeselectronicgearing,triggeringoutputsbasedonposition,updatingprofilesbasedonuserdefinedevents,andsoonFaultDetection,whichincludesstoppingmovesonalimitswitchencounter,safesystemreactiontoemergencystopordrivefaults,watchdog,andsoon

Trajectorygenerator—ProvidespathplanningbasedontheprofilespecifiedbytheuserControlloop—Performsfast,closed-loopcontrolwithsimultaneousposition,velocity,andtrajectorymaintenanceononeormoreaxesThecontrolloophandlesclosingtheposition/velocityloopbasedonfeedback,anditdefinestheresponseandstabilityofthesystem.Forsteppersystems,thecontrolloopisreplacedwithastepgenerationcomponent.Toenablethecontrollooptoexecutefasterthanthetrajectorygeneration,aninterpolationcomponent,orsplineengine,thecontrolloopinterpolatesbetweensetpointscalculatedbythetrajectorygenerator.ThefollowingfigureillustratesthefunctionalarchitectureofNImotioncontrollers.

MotionI/O—AnaloganddigitalI/Othatsendsandreceivessignalsfromtherestofthemotioncontrolsystem.Typically,theanalogoutputisusedasacommandsignalforthedrive,andthedigitalI/Oisusedforquadratureencodersignalsasfeedbackfromthemotor.ThemotionI/Operformspositionbreakpointandhighspeedcapture.Also,thesupervisorycontrolusesthemotionI/Otoachievecertainrequiredfunctionality,suchasreactingtolimitswitchesandcreatingthemovementmodesneededtoinitializethesystem.

NI73xxControllerArchitectureNI73xxcontrollersuseadual-processorarchitecture.Thetwoprocessors,acentralprocessingunit(CPU)andadigitalsignalprocessor(DSP),formthebackboneoftheNImotioncontroller.ThecontrollerCPUisa32-bitmicro-controllerrunninganembeddedrealtime,multitaskingoperatingsystem.ThisCPUofferstheperformanceanddeterminismneededtosolvemostcomplexmotionapplications.TheCPUperformscommandexecution,hostsynchronization,I/Oreaction,andsystemsupervision.TheDSPhastheprimaryresponsibilityoffastclosed-loopcontrolwithsimultaneousposition,velocity,andtrajectorymaintenanceonmultipleaxes.TheDSPalsoclosesthepositionandvelocityloops,anddirectlycommandsthetorquetothedriveoramplifier.MotionI/OoccursinhardwareonanFPGAandconsistsoflimit/homeswitchdetection,positionbreakpoint,andhigh-speedcapture.Thisensuresverylowlatenciesintherangeofhundredsofnanosecondsforbreakpointsandhigh-speedcaptures.RefertotheSynchronizationsectionforinformationaboutbreakpointsandhigh-speedcapture.Themotioncontrollerprocessorismonitoredbyawatchdogtimer,whichishardwarethatcanbeusedtoautomaticallydetectsoftwareanomaliesandresettheprocessorifanyoccur.Thewatchdogtimerchecksforproperprocessoroperation.Ifthefirmwareonthemotioncontrollerisunabletoprocessfunctionswithin62ms,thewatchdogtimerresetsthemotioncontrolleranddisallowsfurthercommunicationsuntilyouexplicitlyresetthemotioncontroller.Thisensuresthereal-timeoperationofthemotioncontrolsystem.Thefollowingfunctionsmaytakelongerthan62mstoprocess:

SaveDefaultsResetDefaultsEnableAutoStartObjectMemoryManagementClearBufferEndStorage

Thesefunctionsaremarkedasnon-real-timefunctions.RefertotheNI-MotionFunctionHelportheNI-MotionVIHelpformoreinformation.


ThefollowingblockdiagramillustratesthephysicalarchitectureoftheNImotioncontrollerhardware.

TipBecausetheNISoftMotionControllerisnotahardwaredevice,informationaboutitsarchitectureisnotcoveredinthistopic.RefertoNISoftMotionControllerArchitectureforinformationaboutthefunctionalarchitecturespecifictotheNISoftMotionController.

NISoftMotionControllerArchitectureTheNI-MotionarchitecturefortheNISoftMotionControllerusesstandardPC-basedplatformsandopenstandardstoconnectintelligentdrivestoareal-timehost.Inthisarchitecture,thesoftwarecomponentsofthemotioncontrollerrunonareal-timehostandallI/Oisimplementedinthedrives.ThisseparationofI/Ofromthemotioncontrollersoftwarecomponentshelpstolowersystemcostandimprovereliabilitybyimprovingconnectivity.TheCANopenstandardisusedtoconnectthesecomponents.WhenyouusetheNISoftMotionControllerwithaCANopendevice,youcandaisychainupto15drivestogetherandconnectthemtothereal-timehost.Thereal-timeProcessDataObjects(PDOs)definedbytheCANopenprotocolareusedtotransferdatabetweenthedrivesandhost.AllI/OrequiredbythemotioncontrollerisimplementedbyCANopendrivesthatsupporttheDeviceProfile402forMotionControl.Currently,theNISoftMotionControllersupportsonlyCANopendrivesfromCopleyControlsCorp.WhenusedwithCANopendevices,theSupervisoryControlandTrajectoryGenerationcomponentsoftheNISoftMotionControllerexecuteinareal-timeenvironmentthatisrunningLabVIEWReal-TimeModule(ETS).Ifyourmotioncontrolsystemuses8axesorfewer,thesupervisorycontrolandtrajectorygenerationloopsexecuteevery10milliseconds.Ifyourmotioncontrolsystemusesmorethan8axes,thesupervisorycontrolandtrajectorygenerationloopsexecuteevery20milliseconds.WhenyouusetheNISoftMotionControllerwithaCANopendrive,thedriveimplementsthecontrolloopandinterpolation,asshowninthefollowingfigure.

Inthisconfiguration,theI/Oandthecontrolloopexecuteonthe

CANopendrive.TheNISoftMotionControllerusesanNI-CANdevicetocommunicatetotheCANbus.

NISoftMotionControllerCommunicationWatchdogThesupervisorycontrolintheNISoftMotionControllercontinuouslymonitorsallcommunicationwiththedrivesconnectedtothehost.Ifanydrivefailstoupdateitsdatainthehostloopupdateperiod,theaxiscorrespondingtothatdriveisdisabledandthecommunicationwatchdogstatusbit,whichisreturnedbytheReadPerAxisStatusVIorfunction,issettoTRUE.Similarly,alldrivesconnectedtotheNISoftMotionControllerareconfiguredtogointoafaultstateifthedatafromtheNISoftMotionControllerisnotupdatedeveryhostloopupdateperiodonthedrives.ThecommunicationwatchdogfunctionalityensuresthattheNISoftMotionControlleroperatesinrealtime.

TipTogetanaxisoraxesoutofthecommunicationwatchdogstate,resettheNISoftMotionController.

NI-MotionCReferenceHelp.chm::/flex_read_axis_status.html

CreatingNI-MotionApplicationsThefollowingfiguredescribesthestepsforcreatinganapplicationwithNI-Motion,anddescribesthegenericstepsrequiredtodesignamotionapplication.

ForinformationaboutinteractionwithotherI/O,suchasaNationalInstrumentsdataand/orimageacquisitiondevices,refertoSynchronization.

ProgrammingwithNI-MotionYoucanusetheC/C++functionsandLabVIEWVIs,includedwithNI-Motion,toconfigureandexecutemotioncontrolapplications.ThissectioncoverstheNI-MotionalgorithmsyouneedtouseallthefeaturesofNI-Motion.Eachtaskdiscussionusesthesamestructure.First,agenericalgorithmflowchartshowshowthecomponentpiecesrelatetoeachother.Then,thetaskdiscussiondetailsanyaspectsofcreatingthetaskthatarespecifictoLabVIEWorC/C++programming,completewithdiagramsandcodeexamples.

NoteTheLabVIEWblockdiagramsandC/C++codeexamplesaredesignedtoillustrateconcepts,anddonotcontainallthelogicorsafetyfeaturesnecessaryformostfunctionalapplications.

RefertotheNI-MotionFunctionHelportheNI-MotionVIHelpfordetailedinformationaboutspecificfunctionsorVIs.


WhatYouNeedtoKnowaboutMovesThissectiondiscussestheconceptsnecessaryforprogrammingmotioncontrolincludingmoveprofiles,movetypes,velocityandaccelerationvalues,andtimingloops.

MoveProfilesThebasicfunctionofamotioncontrolleristomakemoves.Thetrajectorygeneratortakesinthetypeofmoveandthemoveconstraintsandgeneratespoints,orinstantaneouspositions,inrealtime.Then,thetrajectorygeneratorfeedsthepointstothecontrolloop.Thecontrolloopconvertseachinstantaneouspositiontoavoltageortostep-and-directionsignals,dependingonthetypeofmotoryouareusing.Moveconstraintsarethemaximumvelocity,acceleration,deceleration,andjerkthatthesystemcanhandle.Thetrajectorygeneratorcreatesavelocityprofilebasedonthesemoveconstraintvalues.Therearetwotypesofprofilesthatcanbegeneratedwhilemakingthemove:trapezoidalands-curve.

TrapezoidalWhenyouuseatrapezoidalprofile,theaxesaccelerateattheaccelerationvalueyouspecify,andthencruiseatthemaximumvelocityyouload.Basedonthetypeofmoveandthedistancebeingcovered,itmaybeimpossibletoreachthemaximumvelocityyouset.Thevelocityoftheaxis,oraxes,inacoordinatespaceneverexceedsthemaximumvelocityloaded.Theaxesdeceleratetoastopattheirfinalposition,asshown.

S-CurveTheaccelerationanddecelerationportionsofans-curvemotionprofilearesmooth,resultinginlessabrupttransitions,asshowninthefollowingfigure.Thislimitsthejerkinthemotioncontrolsystem,butincreasescycletime.Thevaluebywhichtheprofileissmoothediscalledthemaximumjerkors-curvevalue.

BasicMovesTherearefourbasicmovetypes:

ReferenceMove—InitializestheaxestoaknownphysicalreferencesuchasahomeswitchorencoderindexStraight–LineMove—MovesfrompointAtopointBinastraightline.ThemovecanbebasedonpositionorvelocityArcMove—MovesfrompointAtopointBinanarcorhelixContouredMove—Auser-definedmove;yougeneratethetrajectory,andthepointsloadedintothemotioncontrolleraresplinedtocreateasmoothprofile

Themotioncontrollerusesthespecifiedmoveconstraints,alongwiththemovedata,suchasendpositionorradiusandtravelangle,tocreateamotionprofileinallthemovesexceptthecontouredmoves.Contouredmovesignorethemoveconstraintsandfollowthepointsyouhavedefined.

CoordinateSpaceWiththeexceptionofthearcmove,youcanexecuteallbasicmovesoneitherasingleaxisoronacoordinatespace.Acoordinatespaceisalogicalgroupingofaxes.Ifyouareperformingamovethatusesmorethanoneaxis,youmustspecifyacoordinatespacemadeupoftheaxesthemovewilluse,asshowninthefollowingfigure.

NoteArcmovesalwaysexecuteonacoordinatespace.

UsetheConfigureVectorSpaceVIorfunctiontoconfigureacoordinatespace.Thisfunctioncreatesalogicalmappingofaxesandtreatstheaxesaspartofacoordinatespace.Thefunctionthenexecutesthemovegeneratedbythetrajectorygeneratoronthevector,andtreatsallthemoveconstraintsasvectorvalues.

NI-MotionCReferenceHelp.chm::/flex_config_vect_spc.html

Multi-StartsversusCoordinateSpacesCoordinatespacesalwaysstartandendthemotionofallaxessimultaneously.Youcanusemulti-startstocreateasimilareffectwithoutgroupingaxesintocoordinatespaces.Usingamulti-startautomaticallystartsallaxesvirtuallysimultaneously.Tosimultaneouslyendthemoves,youmustcalculatethemoveconstraintstoendtravelatthesametime.Incoordinatespaces,thesevaluesarecalculatedautomatically.

TrajectoryParametersUsetrajectoryparameterstocontrolthemovesyouprograminNI-Motion.Alltrajectoryparametersforservoaxesareexpressedintermsofquadratureencodercounts.Parametersforopen-loopandclosed-loopstepperaxesareexpressedinsteps.Forservoaxes,theencoderresolution,whichisexpressedincountsperrevolution,determinestheultimatepositionalresolutionoftheaxis.Forstepperaxes,thenumberofstepsperrevolutiondependsuponthetypeofstepperdriveandmotoryouareusing.Forexample,asteppermotorwith1.8°/step(200steps/revolution)usedinconjunctionwitha10Xmicrostepdrivehasaneffectiveresolutionof2,000stepsperrevolution.Resolutiononclosed-loopstepperaxesislimitedtothestepsperrevolutionorencodercountsperrevolution,whichevervalueismorecoarse.Floating-pointversusfixed-pointparameterrepresentationandtimebasearetwoadditionalfactorsthataffectthewaytrajectoryparametersareloadedtotheNImotioncontrollerascomparedtohowtheyareusedbythetrajectorygenerators.

Floating-PointversusFixed-PointParametersOnNI73xxmotioncontrollers,youcanloadsometrajectoryparametersaseitherfloating-pointorfixed-pointvalues,buttheinternalrepresentationontheNImotioncontrollerisalwaysfixed-point.Youmustconsiderthisfunctionalitywhenworkingwithonboardvariables,inputs,andreturnvectors.Thisfunctionalityalsohasasmalleffectonparameterrangeandresolution.TheNISoftMotionControllerusesa64-bitfloatingpointtrajectorygenerator.Therangesforallmoveconstraintsarethefull64-bitrange,whichincludesmaximumvelocity,maximumacceleration,maximumdeceleration,maximumaccelerationjerk,maximumdecelerationjerk,andvelocityoverridepercentage.Allarcparametersthatusefloatingpointalsosupportthefull64-bitfloatingpointrange.

NI73xxMoveConstraintValuesThefollowingsectionsdefinetheminimumandmaximumvaluesformoveconstraintsaswellasadditionalinformationabouttheresolutionofthevelocityoverridevalueandarcangle.Velocityandaccelerationvaluesareloadedincounts/s,RPM,RPS/s,steps/s,andsoon,whichareallfunctionsofsecondsorminutes.However,thetrajectorygeneratorupdatestargetpositionattheTrajectoryUpdateRate,whichisprogrammablewiththeEnableAxesVIorfunction.Thismeansthattherangefortheseparametersdependsontheupdaterateselected.NI73xxVelocityinRPMNI73xxVelocityinCounts/sorSteps/s

NI73xxAccelerationinCounts/s2

NI73xxAccelerationinRPS/sNI73xxVelocityOverrideinPercentNI73xxArcAnglesinDegrees

NI-MotionCReferenceHelp.chm::/flex_enable_axis.html

NI73xxVelocityinRPMVelocityvaluesinRPMareconvertedtoaninternal16.16fixed-pointformatinunitsofcounts(steps)persampleperiod(updateperiod)beforebeingusedbythetrajectorygenerator.NI-Motioncancontrolvelocityto1/65,536ofacountorsteppersample.Thefollowingtableshowstheminimumandmaximumvelocityincounts/min.UsetheformulashownintheCalculationBasedonUnitscolumntodeterminethecounts/minvaluetoRPM.

UpdateRate MIN MAX Calculation

BasedonUnits62.5µs 14.648438

counts/minForservomotors,themaximumcounts/minis1.2billionindependentoftheupdaterate.

±RPMmax=MAX×1/rwherer=counts/revolution

125µs 7.324219counts/min

187.5µs

4.882813counts/min


312.5µs

2.929688counts/min

Forsteppermotors,themaximumcounts/minvalueisdependentonthecontroller:

480millioncounts/minforNI7350240millioncounts/minforNI7330/7340/7390

±RPMmin=MIN×1/rwherer=counts/revolution


437.5µs

2.092634counts/min


YoucancalculatethisminimumvelocityincrementinRPMwiththefollowingformula:minimumRPM=Vmin×( )×60×( )

whereVmin=1/65,536counts/sampleorsteps/sampleTs=sampleperiodinsecondspersample60=numberofsecondsinaminuteR=countsorstepsperrevolution

orminimumRPM=MIN×

YoualsocancalculatetheminimumvelocityusingtheformulashownintheCalculationBasedonUnitscolumn.Foratypicalservoaxiswith2,000countsperrevolutionoperatingata250µsupdaterate,theminimumRPMincrementis

× ×60× =0.00183105RPMor

3.662109× =0.00183105RPMYoucancalculatethemaximumvelocityinRPMwiththefollowingequation:maximumRPM=Vmax×60×

whereVmax=20MHzforservos8MHzforsteppersonaNI7350controller4MHzforsteppersonaNI7330,NI7340,orNI7390motioncontrollerR=counts/stepsperrevolution

andisconstrainedbyacceleration/decelerationaccordingtothefollowingequation:velocity (65,536×deceleration)acceleration

wherevelocityisincounts/sampleandaccelerationanddecelerationareincounts/sample2.

Fromtheexample,themaximumRPMis

(20×106)×60× =600,000RPMRPMvaluesstoredinonboardvariablesareindouble-precisionIEEEformat(f64).

NI73xxVelocityinCounts/sorSteps/sVelocityvaluesincounts/sorsteps/sarealsoconvertedtotheinternal16.16fixed-pointformatinunitsofcountsorstepspersample(update)periodbeforebeingusedbythetrajectorygenerator.Althoughthemotioncontrollercancontrolvelocityto1/65,536ofacountorsteppersample,itisimpossibletoloadavaluethatsmallwiththeLoadVelocityVIorfunction,asshowninthefollowingformula:Velocityincountsorstep/s=Vmin×

where:Vminis1/65,536counts/sampleorsteps/sampleandTsisthesampleperiodinsecondspersample.

Evenatthefastestupdaterate,Ts=62.5×106

LoadVelocitytakesanintegerinputwithaminimumvalueof1count/sorstep/s.Youcannotloadfractionalvalues.Ifyouneedtoloadavelocityslowerthanonecountorsteppersecond,usetheLoadVelocityinRPMVIorfunction.Youcancalculatethemaximumvelocitywiththefollowingequation:maximumvelocity=Vmax

whereVmax=20MHzforservos8MHzforsteppersonaNI7350controller4MHzforsteppersonaNI7330,NI7340,orNI7390motioncontroller

andisconstrainedbyacceleration/decelerationaccordingtothefollowingequation:velocity (65,536×deceleration)acceleration

wherevelocityisincounts/sampleandaccelerationanddecelerationareincounts/sample2.

NI-MotionCReferenceHelp.chm::/flex_load_velocity.html

NI-MotionCReferenceHelp.chm::/flex_load_rpm.html

NI73xxAccelerationinCounts/s2Accelerationanddecelerationvaluesareconvertedtoaninternal16.16fixed-pointformatinunitsofcounts/s2beforebeingusedbythetrajectorygenerator.Thefollowingtableshowstheminimumandmaximumaccelerationupdateratesincounts/sec2.

UpdateRate MAX MIN

CalculationBasedonUnits

62.5µs 2,048,000,000counts/sec2 3906counts/sec2 Accelmax=MAX

125µs 2,048,000,000counts/sec2 977counts/sec2

187.5µs 910,222,222counts/sec2 434counts/sec2

250µs 512,000,000counts/sec2 244counts/sec2

312.5µs 327,680,000counts/sec2 156counts/sec2 Accelmin=MIN


437.5µs 167,183,673counts/sec2 80counts/sec2


Youcancalculatetheminimumaccelerationincrementwiththefollowingformula:

minimumacceleration/deceleration=Amin×( )2

where

Amin=1/65,536counts/sample2orsteps/sample2

Ts=sampleperiodinsecondspersampleForatypicalservoaxiswith2,000countsperrevolutionoperatingatthe250µsupdaterate,calculatetheminimumacceleration/decelerationincrementusingthefollowingequation:

( )×( )2=244counts/second2

Youcancalculatethemaximumacceleration/decelerationusingthefollowingequation:

maximumacceleration/deceleration=Amax×( )2

where

Amax=32counts/sample2

Ts=sampleperiodinsecondspersampleandisconstrainedaccordingtothefollowingequations:acceleration256 decelerationdeceleration65536 acceleration

NI73xxAccelerationinRPS/sAccelerationanddecelerationvaluesinRPS/sareconvertedtoaninternal16.16fixed-pointformatinunitsofcounts/sample2orsteps/sample2beforebeingusedbythetrajectorygenerator.Thefollowingtableshowstheminimumandmaximumaccelerationupdateratesincounts/sec2.

UpdateRate MAX MIN CalculationBasedon

Units62.5µs 2,048,000,000

counts/sec23906counts/sec2

±RPS/smax=MAX×1/rwherer=counts/revolution

125µs 2,048,000,000counts/sec2

977counts/sec2

187.5µs 910,222,222counts/sec2

434counts/sec2

250µs 512,000,000counts/sec2

244counts/sec2

312.5µs 327,680,000counts/sec2

156counts/sec2

±RPS/smin=MIN×1/rwherer=counts/revolution

375µs 227,555,556counts/sec2

109counts/sec2

437.5µs 167,183,673counts/sec2

80counts/sec2

500µs 128,000,000counts/sec2

61counts/sec2

YoucancalculatetheminimumaccelerationincrementinRPS/swiththefollowingformula:

RPS/sec=Amin×( )2×where

Amin=1/65,536counts/sample2orsteps/sample2

Ts=sampleperiodinsecondspersampleR=countsorstepsperrevolution

orRPM/s=MIN×

Foratypicalservoaxiswith2,000countsorstepsperrevolutionoperatingatthe250µsupdaterate,calculatetheminimumRPS/sincrementusingthefollowingequation:

( )×( )2× =0.122070RPS/sor

244× =0.122YoucancalculatethemaximumRPS/susingthefollowingequation:

maximumRPS/s=Amax×( )2×( )

where

Amax=32counts/sample2

Ts=sampleperiodinsecondspersampleR=countsorstepsperrevolution

andisconstrainedaccordingtothefollowingequations:acceleration 256×decelerationdeceleration 65536×acceleration

or

Foratypicalservoaxiswith2,000countsorstepsperrevolutionoperatingatthe250µsupdaterate,calculatethemaximumRPS/sincrementusingthefollowingequation:

32×( )2× =256,000RPS/sRPS/svaluesstoredinonboardvariablesareindouble-precisionIEEEformat(f64).

NI73xxVelocityOverrideinPercentTheLoadVelocityOverrideVIorfunctiontakesasingle-precisionfloating-point(f32)datavaluefrom0to150%,butvelocityoverrideisinternallyimplementedasavelocityscalefactorof0to384withanimplicitfixeddenominatorof256.NI-Motionusesthevelocityoverridetoincreasethespeedofthecalculationforthesakeofcalculationspeed—thedivisionisashiftrightbyeightbits.Theresolutionforvelocityoverrideisthereforelimitedto1/256,orabout0.39%.

NoteTheconversionfromfloating-pointtofixed-pointisperformedonthehostcomputer,notonthemotioncontroller.Toloadvelocityoverridefromanonboardvariable,youmustusetheintegerrepresentationof0to384,where384correspondsto150%.

NoteIfthedistanceofthemoveistoosmall,itmaynotbepossibletoreachthecommandedmaximummoveconstraints.Insuchinstances,NI-Motionadjuststhemoveconstraintslowertoreachthecommandedposition.

NI-MotionCReferenceHelp.chm::/flex_load_velocity_override.html

NI73xxArcAnglesinDegreesTheLoadCircularArc,LoadHelicalArc,andLoadSphericalArcVIs/functionstakeangleparametersindegreesasdouble-precisionfloating-pointvalues.Thesevaluesareconvertedtoaninternal16.16fixed-pointrepresentationwheretheintegerpartcorrespondstomultiplesof45°(forexample,360°isrepresentedas0x00080000).Usethefollowingformulatoconvertfromfloating-pointtofixedpoint:

where:Qisthequotient,theintegermultipleof45°Ristheremainder.

Forexample,94.7°isrepresentedin16.16formatasfollows:

Theminimumangularincrementistherefore

×45º=0.000687º

NoteTheconversionfromfloating-pointtofixed-pointisperformedonthehostcomputer,notontheNImotioncontroller.ToloadarcVIsfromonboardvariables,youmustusethe16.16fixed-pointrepresentationforallangles.

NI73xxArcMoveLimitationsThefollowingarelimitationstothevelocityandaccelerationofarcmoves.

NoteRoundtheresultoftheseequationstothenearestinteger.

ArcmovesmustmeettherequirementsofthefollowingequationsoranNIMC_invalidVelocityErrorisgenerated:V×P×4<R

and

whereV=Velocityincounts/sP=PIDsamplerateinsecondsI=CoarseArcPointsIntervalPeriod(10msor20ms)inseconds,configuredinMAXR=Radiusincounts

ArcmovesmustmeettherequirementsofthefollowingequationsoranNIMC_invalidAccelerationErrorisgenerated:A×P×4<R

and

where

A=Acceleration/decelerationincounts/s2

P=PIDsamplerateinsecondsI=CoarseArcPointsIntervalPeriod(10msor20ms)inseconds,configuredinMAXR=Radiusincounts

TimingLoopsNationalInstrumentsrecommendsthatyouusethelooptimingsdiscussedinthefollowingsections.

StatusDisplayWhenyouaredisplayingstatusinformationtotheuser,suchasposition,movestatus,orvelocity,anupdateratefasterthan60mshasnovalue.Infact,thereisnoneedtoupdateadisplayanyfasterthan22Hzbecausethehumaneyecandetectflickeronlyatrefreshratesslowerthan22Hz.However,youmightseeflickerinmonitorsataround60Hz,becauseofinterferencewithartificiallightfromlightbulbsthatrunona60HzACsignal.Therecommendedstandardis60msbecauseonemightneedmultiplefunctioncallswithinonelooptoacquireallthenecessarydata.

GraphingDataWhenacquiringdataforgraphingortrackingpurposes,a10msupdatetimesuitsmostapplications.MAX,forexample,updatesitsmotiongraphsevery10ms.Thisupdatetimeequatesto100sampleseverysecondandprovidesenoughresolutionfortypicalapplications.Considerhowaccuratethegraphdisplayiswhenchoosingthetimingfortheloop.

EventPollingUseapollingintervalof5mswhenpollingforatime-criticaleventthatmustoccurbeforetheprogramcontinues.Thisintervalisfastenoughtosatisfymosttime-criticalpollingneeds,althoughcertainhigh-speedapplicationsmayrequireafasterinterval.Considertheallowableresponsetimewhenchoosingapollinginterval.Forexample,tosynchronizethemotionwiththeacquisitioninanapplicationwhereauserplacesanobjectunderthescanareaandclicksaScanbutton,youcreateperiodicbreakpointsevery10countstotriggeradataacquisitionoverRTSI.Inthisexample,theloopneedsonlytoreadthepositionandwaitforthemovetocompletebeforeendingthescan.Althoughtheprogrampollsforanevent(movecomplete),noactionisbeingtriggeredbythemovecomplete.Becausethereisnoneedforinstantaneousaction,thereisnoneedtoupdatethepositionanyfasterthan60ms,and60msisacceptableformonitoringthemovecompletestatusaswell.

Straight-LineMovesAstraight-linemoveexecutestheshortestmovebetweentwopointsandcanuseone,two,orthreeaxes.Straight-linemovesareeitherposition-basedorvelocity-based.

Position-BasedStraight-LineMovesPosition-basedstraight-linemovesusethespecifiedtargetpositiontogeneratethemovetrajectory.Forexample,ifthemotoriscurrentlyatpositionzero,andthetargetpositionis100,aposition-basedmovecreatesatrajectorythatmoves100counts(steps).Thecontrollerrequiresthefollowinginformationtomovetoanotherpositioninastraightline:

Startposition—Currentposition,normallyheldoverfromapreviousmoveorinitializedtozeroEndposition—Alsoknownasthetargetposition,orwhereyouwanttomovetoMoveconstraints—Maximumvelocity,maximumacceleration,maximumdeceleration,andmaximumjerkTipWhenyouareusingtheNISoftMotionController,youcanloadseparateaccelerationanddecelerationjerkvalues.

Themotioncontrollerusesthegiveninformationtocreateatrajectorythatneverexceedsthemoveconstraintsandthatmovesanaxisoraxestotheendpositionyouspecify.Thecontrollergeneratesthetrajectoryinrealtime,soyoucanchangeanyoftheparameterswhiletheaxesaremoving.

Straight-LineMoveAlgorithmThestraight-linemovealgorithmincludesthefollowingprocedures:

Loadtargetposition—SpecifiestheendpositionLoadthemoveconstraints—Loadsthevelocity,acceleration,deceleration,andjerkvaluesStartmotion—Startsthemove

Thestartpositionisalwaysthecurrentpositionoftheaxisoraxes.Youcanloadtheendpositionaseitheranabsolutepositiontomovetoorasapositionrelativetothestartingposition.Althoughyoucanupdateanyparameterwhilethemoveisinprogress,thenewparameterisusedonlyafterasubsequentStartorBlendMove.

TipYoumustloadthemoveconstraintsonlyiftheyaredifferentfromwhatwaspreviouslyloaded.

Straight-LineMoveLabVIEWDiagramThefollowingblockdiagramsdemonstrateusingNI-Motiontocompletea1Dand2Dstraight-linemove,respectively.

TipRefertoNI-Motion\Documentation\Examples\NI-MotionUserManual\fortheLabVIEWVIsfortheseexamples.

1DStraight-LineMoveBlockDiagram

1LoadVelocity 4LoadS-CurveTime

7StartMotion

2LoadAcceleration/Deceleration

5SetOperationMode

8ReadperAxisStatus


6LoadTargetPosition

9MotionErrorHandler

2DStraight-LineMoveBlockDiagram

1ConfigureVectorSpace

5LoadS-CurveTime

9CheckMoveCompleteStatus

2LoadVelocity 6SetOperationMode

10ReadperAxisStatus


7LoadTargetPosition

11ReadperAxisStatus


8StartMotion 12MotionErrorHandler

Straight-LineMoveC/C++CodeTipThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertoNI-Motion\Documentation\Examples\NI-MotionUserManual\forfilesthatarecompleteandcompileasis.

1DStraight-LineMoveCode

2DStraight-LineMoveCode

Velocity-BasedStraight-LineMovesSomemotionapplicationsrequiremovesthattravelinastraightlineforaspecificamountoftimeatagivenspeed.Thistypeofmoveisknownasvelocityprofilingorjogging.Youcanuseamotioncontrolapplicationtomoveamotoratagivenspeedforaspecifictime,andthenchangethespeedwithoutstoppingtheaxis.Thesignoftheloadedvelocityspecifiesthedirectionofmotion.Positivevelocityimpliesforwardmotionandnegativevelocityimpliesreversemotion.

TipYoucanchangethemoveconstraintsduringavelocitymove.

Velocity-BasedStraight-LineMoveAlgorithmThefollowingfigureshowsagenericvelocity-basedstraight-linemovealgorithmapplicabletobothC/C++andLabVIEWcode.

LoadingasecondvelocityandexecutingtheStartMotionVIorfunctioncausesthemotioncontrollertoaccelerateordeceleratetothenewlyloadedvelocityusingtheaccelerationordecelerationparameterslastloaded.TheaxisdeceleratestoastopusingtheStopMotionVIorfunction.Thevelocityprofilecreatedintheexamplecodeisshowninthefollowingfigure.

NI-MotionCReferenceHelp.chm::/flex_start.html

NI-MotionCReferenceHelp.chm::/flex_stop_motion.html

Velocity-BasedStraight-LineMoveLabVIEWDiagramThefollowingblockdiagramdemonstratesusingNI-Motiontocompleteavelocity-basedstraight-linemove.



9StartMotion


6StartMotion 10ReadperAxisStatus


7ReadperAxisStatus

11StopMotion

4LoadS-CurveTime 8LoadVelocity 12MotionErrorHandler

Velocity-BasedStraight-LineMoveC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)

u8boardID;//Boardidentificationnumber

u8axis;//Axisnumber

u16csr=0;//Communicationstatusregister

u16axisStatus;//Axisstatus

i32moveTime1;//Timeforthe1stsegment

i32moveTime2;//Timeforthe2ndsegment

i32initialTime;

i32currentTime;

//Variablesformodalerrorhandling

u16commandID;//ThecommandIDofthefunction

u16resourceID;//TheresourceID

i32errorCode;//Errorcode

///////////////////////////////

//SettheboardID

boardID=3;

//Settheaxisnumber

axis=1;

//Movetimeforthefirstsegment

moveTime1=5000;//milliseconds

//Movetimeforthesecondsegment


////////////////////////////////

//------------------------------------------------------------

//Firstsegment

//------------------------------------------------------------

//Setthevelocityforthemove(incounts/sec)

err=flex_load_velocity(boardID,axis,10000,0xFF);

CheckError;

//Settheaccelerationforthemove(incounts/sec^2)

err=flex_load_acceleration(boardID,axis,NIMC_ACCELERATION,100000,0xFF);

CheckError;

//Setthedecelerationforthemove(incounts/sec^2)

err=flex_load_acceleration(boardID,axis,NIMC_DECELERATION,100000,0xFF);

CheckError;

//Setthejerk(s-curvevalue)forthemove(insampleperiods)

err=flex_load_scurve_time(boardID,axis,100,0xFF);

CheckError;

//Settheoperationmodetovelocity

err=flex_set_op_mode(boardID,axis,NIMC_VELOCITY);

CheckError;

//Startthemove

err=flex_start(boardID,axis,0);

CheckError;

//Waitforthetimeforfirstsegment

initialTime=timeGetTime();

do

//Checkthemovecompletestatus/followingerror/axisoffstatus

err=flex_read_axis_status_rtn(boardID,axis,&axisStatus);

CheckError;

//Readthecommunicationstatusregisterandcheckthemodalerrors

err=flex_read_csr_rtn(boardID,&csr);

CheckError;

//Checkthemodalerrors

if(csr&NIMC_MODAL_ERROR_MSG)

err=csr&NIMC_MODAL_ERROR_MSG;

CheckError;

//Getthecurrenttimeandcheckiftimeisoverforthefirstsegment

currentTime=timeGetTime();

if((currentTime-initialTime)>=moveTime1)break;

Sleep(50);//Checkevery50ms

while(!(axisStatus&NIMC_MOVE_COMPLETE_BIT)&&!(axisStatus&NIMC_FOLLOWING_ERROR_BIT)&&!(axisStatus&NIMC_AXIS_OFF_BIT));//

//------------------------------------------------------------

//Secondsegment

//------------------------------------------------------------



CheckError;

//Startthemove-toupdatethevelocity


CheckError;

//Waitforthetimeforsecondsegment


do



CheckError;



CheckError;




CheckError;

//Getthecurrenttimeandcheckiftimeisoverforthesecondsegment





//Deceleratetheaxistoastop

err=flex_stop_motion(boardID,axis,NIMC_DECEL_STOP,0);

CheckError;

return;//ExittheApplication

/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//

nimcHandleError;//NIMCCATCHTHIS:

//ChecktoseeiftherewereanyModalErrors


do

//GetthecommandID,resourceandtheerrorcodeofthemodal

//errorfromtheerrorstackontheboard

flex_read_error_msg_rtn(boardID,&commandID,&resourceID,&errorCode);

nimcDisplayError(errorCode,commandID,resourceID);

//ReadtheCommunicationStatusRegister

flex_read_csr_rtn(boardID,&csr);

while(csr&NIMC_MODAL_ERROR_MSG);

else//Displayregularerror

nimcDisplayError(err,0,0);


VelocityProfilingUsingVelocityOverrideYoualsocanusetheLoadVelocityOverrideVIorfunctiontoshiftfromonevelocitytoanotherwhileexecutingmoves.Whenyouusethisfunction,youindicatethenewvelocityintermsofapercentageoftheoriginallyloadedvelocityinsteadofexplicitlystatingthevelocityyouwanttochangeto.Forexample,120percentofanoriginalvelocityof10,000changesthevelocityto12,000.Thetransitionbetweenvelocitiesfollowsallothermoveconstraints.

NI-MotionCReferenceHelp.chm::/flex_load_velocity_override.html

VelocityProfilingUsingVelocityOverrideAlgorithmThefollowingfigureshowsavelocity-basedstraight-linemovealgorithmshowingtheuseofvelocityoverrideapplicabletobothC/C++andLabVIEWcode.

VelocityProfilingUsingVelocityOverrideLabVIEWDiagramThefollowingblockdiagramdemonstratesusingNI-MotiontodovelocityprofilingusingVelocityOverride.



9ReadperAxisStatus


6StartMotion 10StopMotion


7ReadperAxisStatus

11MotionErrorHandler

4LoadS-CurveTime 8LoadVelocityOverride

VelocityProfilingUsingVelocityOverrideC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)


u8axis;//Axisnumber



i32moveTime1;//Timeforthe1stsegment

i32moveTime2;//Timeforthe2ndsegment

i32initialTime;

i32currentTime;





///////////////////////////////

//SettheboardID

boardID=3;

//Settheaxisnumber

axis=1;

//Movetimeforthefirstsegment


//Movetimeforthesecondsegment


////////////////////////////////

//------------------------------------------------------------

//Firstsegment

//------------------------------------------------------------



CheckError;



CheckError;



CheckError;



CheckError;



CheckError;

//Startthemove


CheckError;

//Waitforthetimeforfirstsegment


do



CheckError;



CheckError;




CheckError;

//Getthecurrenttimeandcheckiftimeisoverforthefirstsegment





//------------------------------------------------------------

//Secondsegment

//------------------------------------------------------------

//Changethevelocityto80%oftheinitiallyloadedvalue

err=flex_load_velocity_override(boardID,axis,80,0xFF);

CheckError;

//Waitforthetimeforsecondsegment


do



CheckError;



CheckError;




CheckError;

//Getthecurrenttimeandcheckiftimeisoverforthesecondsegment





//Deceleratetheaxistoastop

err=flex_stop_motion(boardID,axis,NIMC_DECEL_STOP,0);

CheckError;

//Resetvelocityoverridebackto100%

err=flex_load_velocity_override(boardID,axis,100,0xFF);

CheckError;


/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do

ArcMovesAnarcmovecausesacoordinatespaceofaxestomoveonacircular,spherical,orhelicalpath.Youcanmovetwo-dimensionalvectorspacesinacircleonlyona2Dplane.Youcanmovea3Dvectorspaceonasphericalorhelicalpath.Eacharcgeneratedbythemotioncontrollerpassesthroughacubicsplinealgorithmthatensuresthesmoothestarc.Thisalsoensuresnegligiblechordalerror,whichiserrorcausedwhentwopointsonthesurfaceofthearcjoinwitheachotherusingastraightline.Acubicsplinealgorithmgeneratesmultiplepointsbetweeneverytwopointsofthearc,ensuringsmoothmotion,minimumjerk,andmaximumaccuracyatalltimes.Thedatapathisshowninthefollowingfigure.

NoteArcmovesmustmeettherequirementsoftheequationsinNI73xxArcMoveLimitationsoranNIMC_invalidVelocityErrorisgenerated.

CircularArcsAcirculararcdefinesanarcintheXYplaneofa2Dor3Dcoordinatespace.Thearcisspecifiedbyaradius,startingangle,andtravelangle.Also,likeallcoordinatespacemoves,thearcusesthevaluesofmoveconstraints—maximumvelocity,maximumacceleration,andmaximumdeceleration.

TipFortheNISoftMotionController,thearcgenerationalsousesaccelerationjerkanddecelerationjerkwhilecalculatingthearcmove.

NoteWhenyouuseanNI73xxmotioncontrollertomoveamotorinanarc,youcanuseonlytrapezoidalprofiles.Youdonotusejerktocalculatetheprofileforarcmoves.

Tomoveaxesinacirculararc,themotioncontrollerneedsthefollowinginformation:

Radius—SpecifiesthedistancefromthecenterofthearctoitsedgeStartAngle—Orientsthearconitsplaneusingthestartingpointasanaxistospinaround.Becausethestartingpointforanewarcisfixedbasedonthecurrentposition,movingitscenteraroundthestartingpointalterstheorientationofanewarc.Forexample,thefollowingfigureshowstheeffectofchangingthestartanglefrom0°to180°.

1OriginalArc 2Arcwith180°StartAngleTravelAngle—Indicateshowfarthearctravelsina360°circle.

Forexample,atravelangleof90°executesaquarter-circle,atravelangleof360°createsafullcircle,andatravelangleof720°createstwofullcircles.Apositivetravelanglealwayscreatescounterclockwisecircularmotion.Anegativetravelanglereversesthedirectiontocreateclockwisecircularmotion,asshowninthefollowingfigure.

1PositiveTravelAngle 2NegativeTravelAngle

CircularArcMoveAlgorithmThefollowingfigureshowsagenericcirculararcmovealgorithmapplicabletobothC/C++andLabVIEWcode.

CircularArcMoveLabVIEWDiagramThefollowingblockdiagramdemonstratesusingNI-Motiontocompleteacirculararcmove.



5LoadCircularArc 8ReadperAxisStatus

2LoadVelocity 6StartMotion 9ReadperAxisStatus





CircularArcMoveC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)


u8vectorSpace;//Vectorspacenumber



u16status;

u16moveComplete;





///////////////////////////////

//SettheboardID

boardID=1;

//Settheaxisnumber

vectorSpace=NIMC_VECTOR_SPACE1;

////////////////////////////////

//Configurea2DVectorSpacecomprisingofaxes1and2

err=flex_config_vect_spc(boardID,vectorSpace,1,2,0);

CheckError;


err=flex_load_velocity(boardID,vectorSpace,10000,0xFF);

CheckError;


err=flex_load_acceleration(boardID,vectorSpace,NIMC_ACCELERATION,100000,0xFF);

CheckError;


err=flex_load_acceleration(boardID,vectorSpace,NIMC_DECELERATION,100000,0xFF);

CheckError;

//LoadSphericalArc

err=flex_load_circular_arc(boardID,vectorSpace,5000/*radius*/,0.0/*startAngle*/,180.0/*travelAngle*/,0xFF);

CheckError;

//Startthemove

err=flex_start(boardID,vectorSpace,0);

CheckError;

do

axisStatus=0;

//Checkthemovecompletestatus

err=flex_check_move_complete_status(boardID,vectorSpace,0,&moveComplete);

CheckError;

//Checkthefollowingerror/axisoffstatusforaxis1

err=flex_read_axis_status_rtn(boardID,1,&status);

CheckError;

axisStatus|=status;



CheckError;

axisStatus|=status;



CheckError;




CheckError;

while(!moveComplete&&!(axisStatus&NIMC_FOLLOWING_ERROR_BIT)&&!(axisStatus&NIMC_AXIS_OFF_BIT));//


/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do

SphericalArcsA3Dsphericalarcdefinesa2DcirculararcintheX'Y'planeofacoordinatesystemthatistransformedbyrotationinpitch,asshowninthefirstfigure,andyaw,asshowninthesecondfigure,fromthenormal3Dcoordinatespace(XYZ).

InthetransformedX'Y'Z'space,the3Darcisreducedtoasimpler2Darc.The3Darcisdefinedasa2DcirculararcintheX'Y'planeofatransformedvectorspaceX'Y'Z'.Thistransformedvectorspace,X'Y'Z',isdefinedinorientationonly,withnoabsolutepositionoffset.ItsorientationisrelativetotheXYZvectorspace,andisdefinedintermsofpitchandyawangles.Whenrotatingthroughthepitchangle,theYandY'axesstayalignedwitheachotherwhiletheX'Z'planerotatesaroundthem.Whenrotatingthroughtheyawangle,theY'axisneverleavestheoriginalXYplane,asthenewly-definedX'Y'Z'vectorspacerotatesaroundtheoriginalZ-axis.Theradius,startangle,andtravelangleparametersalsoapplytoasphericalarcthatdefinesthearcintwodimensions.

SphericalArcMoveAlgorithmThefollowingfigureshowsagenericsphericalarcmovealgorithmapplicabletobothC/C++andLabVIEWcode.

SphericalArcMoveLabVIEWDiagramThefollowingblockdiagramdemonstratesusingNI-Motiontocompleteasphericalarcmove.



5LoadSphericalArc 9ReadperAxisStatus






8ReadperAxisStatus

SphericalArcMoveC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)





u16status;

u16moveComplete;





///////////////////////////////

//SettheboardID

boardID=1;

//Settheaxisnumber


////////////////////////////////

//Configurea3DVectorSpacecomprisingofaxes1,2and3


CheckError;



CheckError;



CheckError;



CheckError;

//LoadSphericalArc

err=flex_load_spherical_arc(boardID,vectorSpace,5000/*radius*/,45.0/*planePitch*/,

45.0/*planeYaw*/,0.0/*startAngle*/,180.0/*travelAngle*/,0xFF);

CheckError;

//Startthemove


CheckError;

do

axisStatus=0;



CheckError;



CheckError;

axisStatus|=status;



CheckError;

axisStatus|=status;



CheckError;

axisStatus|=status;



CheckError;




CheckError;



/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











HelicalArcsAhelicalarcdefinesanarcina3DcoordinatespacethatconsistsofacircleintheXYplaneandsynchronizedlineartravelintheZ-axis.Thearcisspecifiedbyaradius,startangle,travelangle,andZ-axislineartravel.LineartravelisthelineardistancetraversedbythehelicalarcontheZ-axis,asshowninthefollowingfigure.

1SideViewofHelix 3IsometricViewofHelix2TopViewofHelix 4LinearTravel

HelicalArcMoveAlgorithmThefollowingfigureshowsagenerichelicalarcmovealgorithmapplicabletobothC/C++andLabVIEWcode.

HelicalArcMoveLabVIEWDiagramThefollowingblockdiagramdemonstratesusingNI-Motiontocompleteahelicalarcmove.



5LoadHelicalArc 9ReadperAxisStatus






8ReadperAxisStatus

HelicalArcMoveC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)





u16status;

u16moveComplete;





///////////////////////////////

//SettheboardID

boardID=1;

//Settheaxisnumber


////////////////////////////////

//Configurea3DVectorSpacecomprisingofaxes1,2and3


CheckError;



CheckError;



CheckError;



CheckError;

//LoadHelicalArc

err=flex_load_helical_arc(boardID,vectorSpace,5000/*radius*/,0.0/*startAngle*/,

720.0/*travelAngle*/,5000/*lineartravel*/,0xFF);

CheckError;

//Startthemove


CheckError;

do

axisStatus=0;



CheckError;



CheckError;

axisStatus|=status;



CheckError;

axisStatus|=status;



CheckError;

axisStatus|=status;



CheckError;




CheckError;



/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











ContouredMovesAcontouredmovemovesanaxisoracoordinatespaceofaxesinapatternthatyoudefine.Thetrajectorygeneratoronthemotioncontrollerisnotusedduringacontouredmove.Thecontrollertakespositiondataintheformofanarray,andsplinesthedatabeforeoutputtingittotheDACsorstepperoutputs,asshowninthefollowingfigure.

Contouredmovesareusefulwhenyouwanttogenerateatrajectorythatcannotbeconstructedfromstraightlinesandarcs.Toensurethatthemotionissmoothwithminimumjerk,themotioncontrollercreatesintermediatepointsusingacubicsplinealgorithm.Themoveconstraintscommonlyusedtolimitothertypesofmoves,suchasmaximumvelocity,maximumacceleration,maximumdeceleration,andmaximumjerk,havenoeffectoncontouredmoves.However,theNIMotionAssistantprototypingtoolcanremapauser-definedtrajectorybasedonspecifiedmoveconstraints,preservingmovecharacteristicsandmovegeometry.

ContouredMoveAlgorithmThefollowingfigureshowsagenericcontouredmovealgorithmapplicabletobothC/C++andLabVIEWcode.

Allcontouredmovesarerelative,meaningmotionstartsfromthepositionoftheaxisoraxesatthetimethecontouringmovestarts.Thisbehaviorissimilartothewayarcmoveswork.Dependingontheoperationmodeyouuse,youcanloadabsolutepositionsinthearrayorrelativepositions,whichimplyincrementalpositiondifferencesbetweencontouringpoints.

AbsoluteversusRelativeContouringAllpositionsinacontouringbufferarerelativetothecurrentpositionwhenstarting.Thereisanassumed0pointthatthefirmwareaddstothefrontofthebufferofpoints.Forexample,ifthecontourbufferis[10,20,30,40],thepositionsare[0,10,20,30,40]inthefirmware.Whenacontourmovestartsittakesasnapshotofthecurrentpositionaccordingtothefollowingequation:StartPosition=currentPosition.

Thestartpositionisaddedtoeachpointinthebuffertogettheactualpositiontomovethroughaccordingtothefollowingequation:Point=StartPosition+bufferPosition[n].

Ifthecurrentpositionis100,andthebufferis[10,20,30,40],thecontourmovefollowsthesepoints:[100,110,120,130,140].Thedifferencebetweenabsolutecontouringandrelativecontouringishowthepointsinthebufferaretreated.Thepreviousexamplewasofanabsolutecontourmove.Arelativecontourmovetreatsthepointsasdeltasaccordingtothefollowingformula:Point[n]=Point[n-1]+bufferPosition[n]

Forarelativecontourmovethatstartsatposition100andincludesabufferwiththefollowingvalues:[10,20,30,40],thepointsthecontourmovefollowsare[100,110,130,160,200].Forcontouredmoves,notwoconsecutivepointscandifferbymorethan2151.Forabsolutepositionmode,thefirstpositioninthearraypassedtothecontrollermustbelessthan2151,andanytwoconsecutivepointsmustbelessthan2151.Forrelativepositionmode,nopointpassedtothecontrollercanbegreaterthan2151.AbsoluteversusRelativeContouringExampleIfanaxisstartsatposition0anduseseitherofthefollowingsetsofcontouringpoints,theaxisendsupatposition28.Iftheaxisstartsatposition10,itendsupatposition38inbothcases.

1 3 6 10 14 18 22 25 27 28

1 2 3 4 4 4 4 3 2 1

ContouredMoveLabVIEWDiagramThefollowingblockdiagramdemonstratesusingNI-Motiontocompleteacontouredmove.



5StartMotion 9ClearBuffer

2SetOperationMode

6ReadperAxisStatus 10SetOperationMode

3ConfigureBuffer 7ReadperAxisStatus 11MotionErrorHandler

4WriteBuffer 8CheckMoveCompleteStatus

ThefollowingfiguredemonstratestheTRUEcaseoftheexample.

1CheckBuffer 2WriteBuffer

ContouredMoveC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)





u16status;//Temporarycopyofstatus

u16moveComplete;//Movecompletestatus

i32i;

i32points[1994]=NIMC_SPIRAL_ARRAY;//Arrayof2Dpointstomove

u32numPoints=1994;//Totalnumberofpointstocontourthrough

i32bufferSize=1000;//Thesizeofthebuffertoallocateonthemotioncontroller

f64actualInterval;//Theintervalthecontrollercanreallycontourat

i32*downloadData=NULL;//Thetemporaryarraythatiscreatedtodownloadthepointstothecontroller

u32currentDataPoint=0;//Indicatesthenextpointinthepointsarraythatistobedownloaded

i32backlog;//Indicatestheavailablespacetodownloadmorepoints

u16bufferState;//Indicatesthestateoftheonboardbuffer

u32pointsDone;//Indicatesthenumberofpointsthathavebeenconsumed

u32dataCopied=0;//Keepstackofthepointscopied





///////////////////////////////

//SettheboardID

boardID=1;

//Settheaxisnumber


////////////////////////////////



CheckError;

//Settheoperationmodetoabsoluteposition

err=flex_set_op_mode(boardID,vectorSpace,NIMC_ABSOLUTE_CONTOURING);

CheckError;

//Configurebufferonmotioncontrollermemory(RAM)

//Noterequestedtimeintervalishardcodedto10milliseconds

err=flex_configure_buffer(boardID,1/*buffernumber*/,vectorSpace,NIMC_POSITION_DATA,bufferSize,numPoints,NIMC_TRUE,10,&actualInterval);

CheckError;

//Sendthefirst1000pointsofthedata

downloadData=malloc(sizeof(i32)*bufferSize);

for(i=0;i<bufferSize;i++)

downloadData[i]=points[i];

currentDataPoint++;

err=flex_write_buffer(boardID,1/*buffernumber*/,bufferSize,0,downloadData,0xFF);

free(downloadData);

downloadData=NULL;

CheckError;

//StartMotion


CheckError;

for(;;)

axisStatus=0;

//Checkforavailablespaceanddownloadremainingpointsevery50milliseconds

Sleep(50);

//Checktoseeifwehavemorepointstodownload

if(currentDataPoint<numPoints)

err=flex_check_buffer_rtn(boardID,1/*buffernumber*/,&backlog,&bufferState,&pointsDone);

CheckError;

if(backlog>=300)

downloadData=malloc(sizeof(i32)*backlog);

dataCopied=0;

for(i=0;i<backlog;i++)

if(currentDataPoint>numPoints)break;

downloadData[i]=points[currentDataPoint];

currentDataPoint++;

dataCopied++;

err=flex_write_buffer(boardID,1/*buffernumber*/,dataCopied,0,downloadData,0xFF);

free(downloadData);

downloadData=NULL;

CheckError;



CheckError;

if(moveComplete)break;

//Checkforaxisoffstatus/followingerrororanymodalerrors



CheckError;




CheckError;

//Checkthemotoroffstatusonalltheaxesoraxis


CheckError;

axisStatus|=status;


CheckError;

axisStatus|=status;

if((axisStatus&NIMC_FOLLOWING_ERROR_BIT)||(axisStatus&NIMC_AXIS_OFF_BIT))

break;//Breakoutoftheforloopasanaxiswaskilled

//Setthemodebacktoabsolutemodetogetthecontrolleroutofcontouring

//mode

err=flex_set_op_mode(boardID,vectorSpace,NIMC_ABSOLUTE_POSITION);

CheckError;

//Freethebufferallocatedonthecontrollermemory

err=flex_clear_buffer(boardID,1/*buffernumber*/);

CheckError;


/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











ReferenceMovesUsereferencemovestomovetheaxestoaknownstartinglocationandorientation.ReferencefunctionsincludetheFindReferenceVIorfunction,theCheckReferenceVIorfunction,theWaitReferenceVIorfunction,theReadReferenceStatusVIorfunction,theLoadReferenceParametersVIorfunction,andtheGetReferenceParametersVIorfunction.UseCheckReferencetodetermineiftheFindReferenceoperationiscomplete.ThisfunctionisoftenplacedinaloopthatcontinuesuntilthestatusfortheFindReferenceoperationisshowntobecomplete.YoucanuseWaitReferenceifthereisnoneedtomonitorthestatusoftheFindReference.UseaFindReferencemovetoinitiateasearchoperationtofindareferenceposition.Availablesearchoperationsincludehomeswitch,indexpulse,forwardlimitswitch,reverselimitswitch,center,orrunsequence.RefertotheNI-MotionVIHelportheNI-MotionFunctionHelpforinformationaboutreferencemoveoptions.

NI-MotionCReferenceHelp.chm::/flex_find_reference.html

NI-MotionCReferenceHelp.chm::/flex_check_reference.html

NI-MotionCReferenceHelp.chm::/flex_wait_reference.html

NI-MotionCReferenceHelp.chm::/flex_read_reference_status.html

NI-MotionCReferenceHelp.chm::/flex_load_reference_parameter.html

NI-MotionCReferenceHelp.chm::/flex_get_reference_parameter.html


ReferenceMoveAlgorithmThefollowingfigureshowsagenericreferencemovealgorithmapplicabletobothC/C++andLabVIEWcode.

FindHomeSettingtheFindReferencesearchtypetoHomeinitiatesasearchsequenceforahomeinputorothersensorhookeduptothehomeinput.Attributesyoucanspecifyincludetheinitialsearchdirection,theedge(forwardorreverse)ofthehomesignaltostopon,andthedesiredtraveldirectionwhenyouapproachthespecifiedhomeedge.ThesearchisperformedatthemaximumfindvelocityspecifiedbyMaxFindVelocityorMaxFindRPM.Thevelocityoftheaxisissettothisvalueduringthefindoperation.Thevelocityisthenrestoredtoitspreviousvalueafterthesearchcompletes.Whentheinitialsearchdirectionisforward,theaxisstartsmovingintheforwarddirection.Ifthespecifiedhomesignaltransitionisdetected,thefindhomesequencecontinuesbasedontheothercontrolbits.Iftheforwardlimitswitchisencounteredbeforethehomeinput,theaxisautomaticallyreversesdirectionandcontinuessearchingforthehomeinput.Then,ifthereverselimitisencounteredbeforethehomeinput,thesequencestopsandtheHomeFoundstatusisFalse.Ifahomeinputexists,findingitisguaranteed.Asimilarsearchsequenceisfollowedwhentheinitialsearchdirectionisreverse,exceptthesearchstartsinthereversedirection.Youcanconfigurethefindhomesequencetodetecteithertherisingorfallingedgeofthehomesignal,asshowninthefollowingfigures.YoualsocansettheactivestateofthelimitandhomeinputswiththeSetLimitInputPolarityVIorfunctionandSetHomeInputPolarityVIorfunction,respectively.Afterthehomeinputisfound,motionapproachesthehomeedgefromthespecifieddirection.Ifnecessary,theaxistravelspastthehomeedgeandreversesdirectiontoapproachitfromtheprogrammeddirection.Tosmoothlyapproachtheedge,thisportionofthesequenceisexecutedataslowervelocityusingtheApproachVelocityPercentvaluesetwithLoadReferenceParameterVIorfunctionorinMAX.Thisapproachdirectionfeatureisusedtominimizetheeffectsofmotionsystemwindup,backlash,and/orhomesensorhysteresis.

NI-MotionCReferenceHelp.chm::/flex_set_limit_input_polarity.html

NI-MotionCReferenceHelp.chm::/flex_set_home_polarity.html


Theforwardedgeistheedgeofthehomeswitchthathasapositionhigherthanthatofthereverseedge.TheWaitReferenceVIorfunctionreportsthesuccessofaFindHome.WaitReferencealsocanbeusedtoqueryifthefindoperationiscompletebyusingatimeoutof0.YoualsocanmonitorthisstatuswiththeReadReferenceStatusVIorfunctionandReadperAxisStatusVIorfunction.Whenthehomeinputisfound,theHomeFoundstatusissettoTrue.Ifthehomesequencefailstolocatethespecifiededgeofthehomesignal,theHomeFoundstatusisFalse.

NoteNationalInstrumentsrecommendsnotconnectingthehomeinputtoeithertheforwardorreverselimits.Thismightcauseinappropriatebehavior.InsteaduseFindForwardorFindReverse.ConsiderusingFindCenterforstagesifyourgoalistocenterthesystemtothecenteroftravel.

IfyouexecuteaFindHomeonsystemswithoutahomeinput,thesequencealwaysterminatesatthelimitswitchoppositetotheinitialsearchdirection.TheHomeFoundstatusisfalseandtheedgeandapproachdirectionfeaturesarenotapplicable.ConsiderusingFindForwardandReverseLimitsinstead.IfSmartEnableisdisabledyoumustenablebothlimitsandthehomeinputpriortoexecutingtheFindHome.Ifanyofthelimitorhomeinputs


NI-MotionCReferenceHelp.chm::/flex_read_reference_status.html


aredisabledontheaxis,theFindHomedoesnotstartandamodalerrorisgenerated.Also,afteraFindHomesequencecompletes,thehomeinputmustbedisabledbecauseitisnolongerrequired,assumingyoudonotwanttostoponitthenexttimethesystemmovespastit.WiththeSmartEnablefeatureenabledbothlimitsandthehomeinputareautomaticallyenabledpriortoinitiatingthesearch.Afterthesearchcompletes,thelimitsandthehomeinputarereturnedtotheirpreviousstates.IfyouuseSmartEnable,NationalInstrumentsrecommendssettingthedefaultinMAXtoenabletheforwardandreverselimitsanddisablethehomeinput.Afterthehomeinputisfound,anoffsetmoveisperformed,ifspecified.OffsetMovespecifiestheamountanddirectionoftheoffset.ThisoffsetmoveisperformedatthemaximumfindvelocityspecifiedbyMaxFindVelocityorMaxFindRPM.BydefaultOffsetMoveis0,resultinginnooffsetmove.

NoteIfyouaredoinganoffsetmoveafteraFindHome,verifythatyousetthecorrectEdgetoStopOnusingtheLoadReferenceParameterVIorfunctionsothattheoffsetmovedoesnotcrossthehomeswitch.

Aftertheoffsetmoveisperformed,thepositionisresetifResetPosition?istrue.ThepositionissettothevaluesindicatedbyResetPrimaryPositionandResetSecondaryPosition.Thisprocedureestablishesarepeatablereferencepositionthatisasaccurateasthehomeedgelocation.Inclosed-loopencoderbasedsystems,youcanperformaFindIndexafteraFindHometoovercomeanyerrorsinthehomeedgelocation.TheFindIndexoperationallowsyoutogetafixedencoderpositionrelativetoyourhomeinput.Example1Youwanttofindtheforwardedgeofthehomeinputonaxis2andapproachitfromthereversedirection.Youalsowanttoperformanoffsetof500countsintheforwarddirectionandthenresetthepositionto0.Inaddition,youwanttobeginsearchinginthereversedirection.First,thesettingsinMAXmustcorrespondtothefollowing:

Final Search Edge Smart Reset Offset Reset Reset

Direction Direction Enable Position? PrimaryPosition

SecondaryPosition

True(Reverse)

True(Reverse)

False(Forward)

True True 500 0 0

Then,tostartthesearch,callFindReferencewiththefollowingparameters:

axisOrVectorSpace=Axis2(usingLabVIEW)/NIMC_AXIS2(usingC)searchType=FindHome(0)axisOrVSMap=Unused

Asshowninthefollowingfigure,thisFindHomesequencesearchesforthehomeinputattheMaxFindVelocityfromthereversedirection(1).Whenthehomeinputisfound,theaxisdeceleratesandrepositionstothedesiredapproachdirection(2).Then,theforwardedgeisapproachedattheApproachVelocityinthereversedirection(3).

Example2Youwanttofindtheforwardedgeofthehomeinputonaxis2andapproachitfromtheforwarddirection.Youalsowanttoperformanoffsetof500countsinthereversedirectionandthenresetthepositionto0.Inaddition,youwanttobeginsearchinginthereversedirection.First,thesettingsinMAXmustcorrespondtothefollowing:

FinalDirection

SearchDirection

Edge SmartEnable

ResetPosition?

Offset ResetPrimaryPosition

ResetSecondaryPosition

False(Forward)

True(Reverse)

False(Forward)

True True –500 0 0


axisOrVectorSpace=Axis2(usingLabVIEW)/NIMC_AXIS2(usingC)searchType=Home(0)axisOrVSMap=Unused

Asshowninthefollowingfigure,thisFindHomesequencesearchesforthehomeinputfromthereversedirection(1).Whenthehomeinputisfound,theaxisdecelerates(2).ThentheforwardedgeisapproachedattheApproachVelocityintheforwarddirection(3).

Example3Youwanttofindthereverseedgeofthehomeinputonaxis2andapproachitfromthereversedirection.Inaddition,youwanttobeginsearchinginthereversedirection.First,thesettingsinMAXmustcorrespondtothefollowing:

FinalDirection

SearchDirection

Edge SmartEnable

ResetPosition?



True(Reverse)

True(Reverse)

True(Reverse)

True False 0 0 0

Then,tostartthesearch,callFindReferencewiththefollowing

parameters:axisOrVectorSpace=Axis2(usingLabVIEW)/NIMC_AXIS2(usingC)searchType=Home(0)axisOrVSMap=Unused

Asshowninthefollowingfigure,thisFindHomesequencesearchesforthehomeinputfromthereversedirection(1).Whentheforwardedgeofthehomeinputisfound,theaxisdeceleratestotheApproachVelocity(2).ThenthereverseedgeisapproachedattheApproachVelocityinthereversedirection(3).

Example4Youwanttofindthereverseedgeofthehomeinputonaxis2andapproachitfromtheforwarddirection.Inaddition,youwanttobeginsearchinginthereversedirection.First,thesettingsinMAXmustcorrespondtothefollowing:

FinalDirection

SearchDirection

Edge SmartEnable

ResetPosition?



False(Forward)

True(Reverse)

True(Reverse)

True False 0 0 0


axisOrVectorSpace=Axis2(usingLabVIEW)/NIMC_AXIS2

(usingC)searchType=Home(0)axisOrVSMap=Unused

Asshowninthefollowingfigure,thisFindHomesequencesearchesforthehomeinputfromthereversedirection(1).Whenthereverseedgeofthehomeinputisfound,theaxisdecelerates(2).ThenthereverseedgeisapproachedattheApproachVelocityintheforwarddirection(3).

NoteWhentheinitialsearchdirectionisforward,theFindHomebehavioristhereverseoftheexamplesshown.

FindIndexSettingtheFindReferencesearchtypetoIndexinitiatesasearchsequencetofindtheindex(marker)signalofthefeedbackencoder.Attributesyoucanspecifyincludetheinitialsearchdirection,approachvelocitypercent,andsearchdistance.Theencoderindexsignalisaccuratetoonequadraturecountandprovidesamuchmorerepeatablereferencethanusingjustalimitorhomeinputedge.FindIndexistypicallyexecutedafteraFindHome,FindCenter,orFindLimitoperation.Withthisprocedure,thehomeinputneedonlybeaccurateenoughtorepeatedlylocatetheaxiswithinthesameencoderrevolutionorindexperiod.ThenyoucanuseFindIndextofindauniqueinstanceoftheindex.

NoteFindIndexisonlyavailableonaxeswithincrementalencoderfeedback.

WhenperformingaFindIndexoperationafteranotherfind,youmightnoticeinconsistentoperationiftheindex(marker)signalisneartotheedgeofthehomeinputorlimit.Inthiscase,aFindIndexoperationcansometimesbeoffbyonerevolution.Tosolvethis,NationalInstrumentsrecommendsperforminganoffsetmoveonthepreviousfindtomoveawayfromtheindex(marker)signal,andthenperformtheFindIndexoperation.Thesearchsequenceisperformedinthespecifieddirectionatafixedlowvelocityof¼RPSunlessthemaximumfindvelocityisslower.Toguaranteefindingtheindex(ifoneexists),thelengthofthemoveisautomaticallysettoslightlygreaterthanoneencoderrevolution.IfyoupreviouslyperformedaFindForwardLimitoraFindReverseLimitNationalInstrumentsrecommendsyousetthesearchdirectionoftheFindIndextoadirectionoppositetothedirectionoftravelintothelimit.FindIndexusestheApproachVelocityPercentvaluesetwiththeLoadReferenceParameterVIorfunctionorinMAXthroughouttheentiresearchsequence.

NoteIfthevelocityoftheFindIndexoperationisveryhigh,itispossiblethesearchdistanceisreportedcompletebeforeindexfoundreportedcomplete.ThisresultsinIndexFoundstatusreportedasfalse.Toavoidthisyoucaneitherincreasethesearch


distancetoallowmoretimetoreporttheindexfoundand/ordecreasethesearchspeedtoslowdownthesearch.

Innormaloperation,FindIndexuseshigh-speedcapturecircuitrytodetecttheindex.Theaxistypicallyovershootsbyanamountthatvariesdependingonthevelocity,thencomesbacktotheindex.Inmostcasesthisisnotnoticeable.

NoteIfyouareusingalinearencoderorifyourcounts/stepsperrevolutionissettoavalueotherthantheactualcounts/stepsperrevolution,usetheSearchDistanceparametersetwithLoadReferenceParameterorinMAXtoloadacustomsearchdistanceforaFindIndexmove.

TheWaitReferenceVIorfunctionreportsthesuccessofaFindIndex.WaitReferencealsocanbeusedtoqueryifthefindoperationiscompleteusingatimeoutof0.YoualsocanmonitorthisstatuswiththeReadperAxisStatusVIorfunction.WhentheindexisfoundtheIndexFoundstatusissettoTrue.Iftheindexisnotfoundduringthesearchrevolution,theaxiscomestoastopandindicatesthefailurebysettingtheIndexFoundstatustoFalse.Missingtheindexispossibleforanumberofreasonsincludinganincorrectlyconnectedencoderoranincorrectvalueforcountsperrevolution.Refertothemotioncontrollerdocumentationformoreinformationaboutencoderconnectionsandindexphasing.YoucanonlyexecuteaFindIndexonproperlyconfiguredaxesthatarepresentlystoppedorkilled.AttemptingtoexecuteaFindIndexwhiletheaxisisinmotiongeneratesamodalerror.RefertotheErrorsandErrorHandlingsectionoftheNI-MotionVIHelporNI-MotionFunctionHelpformoreinformationabouterrors.IfSmartEnableisdisabledNationalInstrumentsrecommendsyoudisablethehomeinputbeforeperformingaFindIndex.IfyoupreviouslyperformedaFindHome,dependingonthesettings,youmightencounterthehomeinputduringaFindIndex.WiththeSmartEnablefeatureenabledbothlimitsareenabledandthehomeinputisdisabledpriortoinitiatingthesearch.Afterthesearchcompletesthelimitsarereturnedtotheirpreviousstates.IfyouuseSmartEnable,NationalInstrumentsrecommendssettingthedefaultinMAXtoenabletheforwardandreverselimitsanddisablethehomeinput.



NI-MotionCReferenceHelp.chm::/ErrorsandErrorHandling.html

Aftertheindex(marker)signalisfound,anoffsetmoveisperformed.OffsetMovespecifiestheamountanddirectionoftheoffset.ThisoffsetmoveisperformedatthemaximumfindvelocityspecifiedbyMaxFindVelocityorMaxFindRPM.BydefaultOffsetMoveis0,resultinginnooffsetmove.Aftertheoffsetmoveisperformed,thepositionisresetifEnableResetPositionistrue.ThepositionissettothevaluesindicatedbyPrimaryResetPositionandSecondaryResetPosition.

FindForwardandReverseLimitsSettingtheFindReferencesearchtypetoForwardLimitinitiatesasearchsequencetofindtheforwardlimit.SettingthesearchtypetoReverseLimitinitiatesasearchsequencetofindthereverselimit.AttributesyoucanspecifyincludetheInitialSearchDirectionandtheFinalApproachDirection(forwhenthesearchencounterseachofthelimits).ThesearchisperformedatthemaximumfindvelocityspecifiedbyMaxFindVelocityorMaxFindRPM.Thevelocityoftheaxisissettothisvalueduringthefindoperation.Thevelocityisthenrestoredtoitspreviousvalueafterthesearchcompletes.Whenthesearchoperationinitiatestheaxisstartsmovinginthedirectionofthelimit.WhentheaxisencountersthelimitinthatdirectionthesearchcompletesandtheWaitReferenceVIorfunctionreturnsatruevalue.

Afine-tuningoperationisperformedwhenthelimitisreached.Thisprovidesforamoreaccuratesearch.Tosmoothlyapproachtheedge,thisportionofthesequenceisexecutedatafixedlowvelocityof1/4RPSunlessthemaximumfindvelocityisslower.Thisapproachdirectionfeatureisusedtominimizetheeffectsofmotionsystemwindup,backlash,and/orhomesensorhysteresis.Ifthefinalapproachdirectionistheoppositetothedirectionoftravelintothelimit(true),theaxisthenslowlybacksoffthelimituntilthelimitbecomesinactiveagain.Ifthefinalapproachdirectionisthesameasthedirectionoftravelintolimit(false),thentheaxisslowlybacksoffthelimitandre-approachesit.YoualsocansettheactivestateofthelimitwiththeSetLimitInputPolarityVIorfunction.IfSmartEnableisdisabledNationalInstrumentsrecommendsyoudisablethehomeinputbeforeperformingaFindForwardLimitorFindReverseLimit.IfthehomeinputisenabledandencounteredduringaFindCenter,thesearchstopsatthehomeinputandgeneratesamodalerror.WiththeSmartEnablefeatureenabledthelimityouaresearchingforisenabled,theoppositelimitisleftas-is,andhomeinputisdisabledpriortoinitiatingthesearch.Afterthesearchcompletes,thelimitsarereturnedtotheirpreviousstates.IfyouuseSmartEnable,NationalInstruments



recommendssettingthedefaultinMAXtoenabletheforwardandreverselimitsanddisablethehomeinput.Afterthelimitislocated,anoffsetmoveisperformed.OffsetMovespecifiestheamountanddirectionoftheoffset.ThisoffsetmoveisperformedatthemaximumfindvelocityspecifiedbyMaxFindVelocityorMaxFindRPM.UsuallytheOffsetMoveisnegativeforaFindForwardLimitandpositiveforaFindReverseLimit.BydefaultOffsetMoveis0,resultinginnooffsetmove.Aftertheoffsetmoveisperformed,thepositionisresetifResetPosition?istrue.ThepositionissettothevaluesindicatedbyResetPrimaryPositionandResetSecondaryPosition.

FindCenterSettingtheFindReferencesearchtypetoCenterinitiatesasearchsequencepositioningtheaxisinthemiddleoftheforwardandreverselimits.AttributesyoucanspecifyincludetheInitialSearchDirectionandtheFinalApproachDirection(forwhenthesearchencounterseachofthelimits).ThesearchisperformedatthemaximumfindvelocityspecifiedbyMaxFindVelocityorMaxFindRPM.Thevelocityoftheaxisissettothisvalueduringthefindoperation.Thevelocityisthenrestoredtoitspreviousvalueafterthesearchcompletes.Whenthesearchdirectionisforward,theaxisstartsmovingintheforwarddirection.Whenthelimitinthatdirectionisencountered,thedirectionisreversedtofindthereverselimit.Afterbothlimitsarereachedacenterpositioncanbecalculatedfromtherecordedpositions.Theaxisthenproceedstothecalculatedcenter.WhenthecenterisfoundtheWaitReferenceVIorfunctionreturnsatruevalue.Asimilarsearchsequencestartinginthereversedirectionisfollowedwhentheinitialsearchdirectionisreverse.Attheendofeachlimitoftravel,afine-tuningoperationisperformed.Thisprovidesforamoreaccuratesearch.Tosmoothlyapproachtheedge,thisportionofthesequenceisexecutedatafixedlowvelocityof1/4RPSunlessthemaximumfindvelocityisslower.Thisapproachdirectionfeatureisusedtominimizetheeffectsofmotionsystemwindup,backlash,and/orhomesensorhysteresis.Ifthefinalapproachdirectionisoppositetothedirectionoftravelintothelimit(true),theaxisslowlybacksoffthelimituntilthelimitbecomesinactiveagain.Ifthefinalapproachdirectionisthesameasthedirectionoftravelintolimit(false),theaxisslowlybacksoffthelimitandre-approachesit.YoualsocansettheactivestateofthelimitsinMAXorwiththeSetLimitInputPolarityVIorfunction.

IfSmartEnableisdisabledNationalInstrumentsrecommendsyoudisablethehomeinputbeforeperformingaFindCenter.IfthehomeinputisenabledandencounteredduringaFindCenter,thesearchstopsatthehomeinputandgeneratesamodalerror.



WiththeSmartEnablefeatureenabledbothlimitsareenabledandthehomeinputisdisabledpriortoinitiatingthesearch.Afterthesearchcompletesthelimitsarereturnedtotheirpreviousstates.IfyouuseSmartEnable,NationalInstrumentsrecommendssettingthedefaultinMAXtoenabletheforwardandreverselimitsanddisablethehomeinput.Afterthecenterislocated,anoffsetmoveisperformed.OffsetMovespecifiestheamountanddirectionoftheoffset.ThisoffsetmoveisperformedatthemaximumfindvelocityspecifiedbyMaxFindVelocityorMaxFindRPM.BydefaultOffsetMoveis0,resultinginnooffsetmove.Aftertheoffsetmoveisperformed,thepositionisresetifResetPosition?istrue.ThepositionissettothevaluesindicatedbyResetPrimaryPositionandResetSecondaryPosition.

RunSequenceSettingtheFindReferencesearchtypetoRunSequenceinitiatesapredefinedsearchacrossmultipleaxesandmultiplefindtypes.ThesequencerunisspecifiedinMAX.YoualsocanusetheLoadReferenceParameterVIorfunctiontoprogrammaticallysettheSequenceOrderforagivenaxisandsearchtype.TheRunSequenceoptionallowsyoutopre-configureasearchsequence.Thatsequencecanthenberunwithasinglefunction.ThesequencegetssavedwhenyousaveuserdefaultstoFlash(ROM).Tospecifyarunsequenceprogrammatically,youcanuseLoadReferenceParametertosettheSequenceOrderforagivenaxisandsearchtype.TheSequenceOrderreferstothephaseaparticularsearchisin.ThedefaultSequenceOrder0indicatesthataparticularsearchtypeisnotincludedinthesequence.

NoteOnlyonesearchtypeonagivenaxiscanhavethesameSequenceOrdernumber.IfyousettheFindHomeSequenceOrderof2,thensettheFindIndexSequenceOrderto2,FindHomeSequenceOrderresetsto0andFindIndexSequenceOrderis2.Noerrorisreportedifthisisthecase.

WhenspecifyingSequenceOrdersyoumustbesurenottoskipoveranumber,allphasesmustbecontiguous.Anyfindsspecifiedafterthegapisnotexecuted.Forexample,ifyouspecifyaFindCenterSequenceOrderof1andaFindIndexSequenceOrderof3,onlytheFindCenterisexecuted.

ExampleSupposeyouhaveastageconfiguredwithitsx-axistiedtoaxis2,itsy-axistiedtoaxis3,andanotherdeviceattachedtothestagetiedtoaxis1.Ifyouwanttomakesureyoucenterthedeviceattachedtothestagebeforeyoucenteredthestageyoumightsetuparunsequencesimilartothefollowing:

Phase1 Wait Phase2 Wait Phase3Axis1 FindCenter FindIndexAxis2 FindCenter FindIndex


Axis3 FindCenter FindIndex

Thesequenceisspecifiedasdifferentphases.Thenextphasedoesnotstartuntilallfindoperationsinagivenphasearecomplete.Inthisexample,Phase1isthecenteringofaxis1;Phase2consistsoffindingtheindexofaxis1,andcenteringaxes2and3;Phase3consistsoffindingtheindexofaxes2and3.ForthisexampleyouwouldsetFindCenterSequenceOrderonAxis1to1,FindIndexSequenceOrderonAxis1to2,FindCenterSequenceOrderonAxes2and3to2,andFindIndexSequenceOrderonAxes2and3to3.

ReferenceMoveLabVIEWDiagramThefollowingblockdiagramdemonstratesusingNI-Motiontocompleteareferencemove.


1LoadVelocity 4LoadS-CurveTime

7ReadperAxisStatus


5FindReference 8CheckReference


6CheckReference

9MotionErrorHandler

ReferenceMoveC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)


u8axis;//Axisnumber

f64acceleration=100;//AccelerationvalueinRPS/S

f64velocity=200;//VelocityvalueinRPM

u16found,finding;//CheckReferenceStatuses


u16csr=0;//CommunicationstatusRegister

i32position;//Currentpositionofaxis

i32scanVar;//Scanvariabletoreadinvaluesnotsupported

//bythescanffunction





//GettheboardID

printf("EntertheBoardID:");

scanf("%d",&scanVar);

boardID=(u8)scanVar;

//Checkiftheboardisatpowerupresetcondition


CheckError;

if(csr&NIMC_POWER_UP_RESET)

printf("\nTheFlexMotionboardisintheresetcondition.Pleaseinitializetheboardbefore");

printf("runningthisexample.The\"flex_initialize_controller\"functionwillinitializethe");

printf("boardwithsettingsselectedthroughMeasurementandAutomationExplorer\n");

return;

//Gettheaxisnumber

printf("Entertheaxis:");


axis=(u8)scanVar;

//FlushtheStdin

fflush(stdin);

//Loadaccelerationanddecelerationtotheaxisselected

err=flex_load_rpsps(boardID,axis,NIMC_BOTH,acceleration,0xFF);

CheckError;

//Loadvelocitytotheaxisselected

err=flex_load_rpm(boardID,axis,velocity,0xFF);

CheckError;

//StarttheFindReferencemove

err=flex_find_reference(boardID,axis,0,NIMC_FIND_HOME_REFERENCE);

CheckError;

//WaitforfindreferencetocompleteontheaxisAND

//alsocheckformodalerrorsatthesametime

do

//Readthecurrentpositionofaxis

err=flex_read_pos_rtn(boardID,axis,&position);

CheckError;

//Displaythecurrentpositionofaxis

printf("\rAxis%dposition:%10d",axis,position);

//Checkiftheaxishasstoppedb/cofaxisofforfollowingerror


//Checkifthereferencehasfinishedfinding

err=flex_check_reference(boardID,axis,0,&found,&finding);

CheckError;

//ReadtheCommunicationStatusRegister-checkthe

//modalerrorbit


CheckError;


flex_stop_motion(boardID,NIMC_AXIS1,NIMC_DECEL_STOP,0);//StoptheMotion


CheckError;

//testforfindreferencecomplete,followingerror,oraxisoffstatus

while(!(axisStatus&(NIMC_FOLLOWING_ERROR_BIT|NIMC_AXIS_OFF_BIT))&&finding);

printf("\nAxis%dposition:%10d",axis,position);

if(found)

printf("\rAxisfoundreference");

else

printf("\rAxisdidnotfindreference");

printf("\n\nFinished.\n");


/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











BlendingBlending,alsocalledvelocityblending,superimposesthevelocityprofilesoftwomovestomaintaincontinuousmotion.Blendingisusefulwhencontinuousmotionbetweenconcatenatedmovesegmentsisimportant.Examplesofsomeapplicationsthatcanuseblendingarescanning,welding,inspection,andfluiddispensing.Blendingmustoccuronvelocityprofilesoftwomovesegments,sotheendpositionsofeachmovesegmentmayormaynotbereached.Forexample,ifyouareblendingtwostraight-linemovesthatforma90ºangle,theblendedmovemustroundthecornertomakethemovecontinuous.Inthiscase,themoveneverreachestheexactpositionwherethetwostraightlinesmeet,butinsteadfollowstheroundedcorner,asshowninthefollowingfigure.

1StartingPosition 3CornerRoundedbyBlending2EndPoint

Motioncontrollerscanperformblendingbetweentwostraight-linemoves,betweentwoarcmoves,orbetweenstraight-lineandarcmoves.Blendingdoesnotworkforreferenceandcontouredmoves.Becauseblendingoccursonvelocityprofiles,theeffectofreachingtheendpositionsofthemovesegmentsandthemaximumvelocitydependsonthevelocity,acceleration,deceleration,andjerkloadedforthetwomovesegments.Becausetwomovesegmentsarealwaysusedwhileblending,itisveryimportantthatyouwaitfortheblendtocompletebeforeloadingthenextmovesegmentyouwanttoblend.

BlendingAlgorithmThefollowingfigureshowsagenericblendingalgorithmapplicabletobothC/C++andLabVIEWcode.

BlendFactorsTherearethreewaysyoucanstartthesecondmoveinablend:

SuperimposethetwomovesbystartingthesecondmoveasthefirstmovestartstodecelerateStartthesecondmoveafterthefirstprofileiscompleteStartthesecondmoveafterthefirstprofileiscompleteandtheaddeddelaytimehaselapsed

RefertoMoveProfilesformoreinformationaboutmoveprofiles.

SuperimposeTwoMovesSuperimposingtwomovesisthemostcommonuseofblending.Inthiscase,themotioncontrollertriestomaintaincontinuousmotionbysuperimposingthetwomovesegmentssuchthatthesecondmovesegmentstartsitsprofilewhilethefirstmoveisdecelerating,asshowninthefollowingfigure.

1BlendingStarts 3ActualVelocity2BlendisComplete

Thevelocityduringthesuperimpositiondependsonthecruisingvelocity,deceleration,andjerkofthefirstmovesegment,andthejerk,acceleration,andcruisingvelocityofthesecondmovesegment.

BlendafterFirstMoveIsCompleteBlendingmovesafterthefirstmoveiscompletecausesthefirstmovesegmenttocometoacompletestopbeforestartingtheprofileofthesecondsegment,asshowninthefollowingfigure.

1BlendingStarts 2BlendisComplete

Thistypeofblendingisusefulifyouwanttostarttwomovesegments,oneaftertheother,withnodelaybetweenthem.

BlendafterDelayYoucanblendtwomovesafteradelayattheendofthefirstmove,asshowninthefollowingfigure.

1BlendingStarts 3User-DefinedDelay2BlendisComplete

Blendinginthismannerisusefulifyouwanttostarttwomovesegmentsafteradeterministicdelay.Thetwomovesegmentscanbeeitherstraight-linemovesorarcmoves.

BlendedMoveLabVIEWDiagramThefollowingblockdiagramdemonstratesusingNI-Motiontocompleteablendedmove.



8StartMotion 15LoadVectorSpacePosition

2LoadVelocity 9LoadBlendFactor 16BlendMotion3LoadAcceleration/Deceleration

10LoadCircularArc 17CheckMoveCompleteStatus


11BlendMotion 18ReadperAxisStatus

5LoadS-CurveTime 12CheckBlendCompleteStatus

19ReadperAxisStatus

6SetOperationMode 13ReadperAxisStatus


7LoadVectorSpacePosition

14ReadperAxisStatus

BlendedMoveC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//MainFunction

voidmain(void)





u16status;

u16complete;//Moveorblendcompletestatus





///////////////////////////////

//SettheboardID

boardID=1;

//Settheaxisnumber


////////////////////////////////

//Configurea2DVectorSpacecomprisingofaxes1,and2


CheckError;



CheckError;



CheckError;



CheckError;

//Setthejerkorscurveinsampleperiods

err=flex_load_scurve_time(boardID,vectorSpace,1,0xFF);

CheckError;



CheckError;

//Loadthefirststraightlinesegmentstoposition5000,5000

err=flex_load_vs_pos(boardID,vectorSpace,5000,5000,0,0xFF);

CheckError;

//Startthemove


CheckError;

//LoadCircularArc-makingasemicircleinthecounterclockwisedirection

err=flex_load_circular_arc(boardID,vectorSpace,5000/*radius*/,0.0/*startAngle*/,180.0/*travelAngle*/,0xFF);

CheckError;

//Blendthemove

err=flex_blend(boardID,vectorSpace,0);

CheckError;

//Waitforblendtocompletebeforeloadingthenextsegment

do

axisStatus=0;

//Checktheblendcompletestatus

err=flex_check_blend_complete_status(boardID,vectorSpace,0,&complete);

CheckError;



CheckError;

axisStatus|=status;



CheckError;

axisStatus|=status;



CheckError;




CheckError;


while(!complete&&!(axisStatus&NIMC_FOLLOWING_ERROR_BIT)&&!(axisStatus&NIMC_AXIS_OFF_BIT));//

//Loadthefinalstraightlinesegmentstoposition0,0

err=flex_load_vs_pos(boardID,vectorSpace,0,0,0,0xFF);

CheckError;

//Waitformovetocompleteasthisisthefinalsegment

do

axisStatus=0;


err=flex_check_move_complete_status(boardID,vectorSpace,0,&complete);

CheckError



CheckError;

axisStatus|=status;



CheckError;

axisStatus|=status;



CheckError;




CheckError;




/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











ElectronicGearingandCammingUseelectronicgearingorcammingtosynchronizethemovementofoneormoreslaveaxestothemovementofamasterdevice,whichcanbeanencoder,ADC,orthetrajectoryofanotheraxis.Themovementoftheslaveaxesmaybeatahigherorlowergearratiothanthemaster.Forexample,everyturnofthemasteraxismaycauseaslaveaxistoturntwice.

GearingElectronicgearingallowsoneslavemotortobedriveninproportiontoamastermotororfeedbacksensor,suchasanencoderortorque(analog)sensor.Astheslavefollowsthemasterpositionataconstantratio,theeffectissimilartothatoftwoaxesmechanicallygeared.Electronicgearinghasseveraladvantagesovermechanicalgears.Themostnotableisflexibilitybecauseyoucanchangegearratioson-the-fly.Theothermajoradvantagetoelectronicgearingisthatyoucansuperimposeamoveoveragearedaxis.Thesuperimposedmoveisaddedtothegearedprofileoftheslaveaxis,whichallowstheslaveaxistobesynchronizedon-the-fly.Anaxiscanbegearedtoanotheraxis,ortoanencoderorADC.Whenyougearanaxistoanotheraxis,theslaveaxisfollowsthetrajectorygenerationofthemasteraxis.Forexample,ifyoumanuallymovethemasteraxis,theslaveaxisdoesnotmovebecausethetrajectorygeneratorofthemasteraxisisnotactive.Whenyougearanaxistoanencoder,orfeedbackdevice,theslaveaxisfollowsthefeedbackgeneratedbytheencoder.Iftheencoderdetectsmovement,theslavemovesproportionallytoinformationreturnedbytheencoder.Forexample,ifyoutwistthemasteraxisconnectedtotheencoder,theslaveaxisalsoturnsbecauseitisusingthepositioninformationgatheredbytheencoder.WhenanaxisisgearedtoanADC,theslaveaxisfollowsthebinaryvalueoftheADCasifitwereaposition.Forexample,ifthebinarycodefor2Vis6553,theslaveaxistrackstothisposition.

ElectronicGearingAlgorithmThefollowingfigureshowsagenericelectronicgearingalgorithmapplicabletobothC/C++andLabVIEWcode.

AbsoluteversusRelativeGearingThegearratioisusedtodeterminehowfartheslaveaxismustmoveinproportiontothemasterwhengearingisenabled.Thegearratiocanbeabsoluteorrelative.Slaveaxismove=Masteraxisposition×Gearratio

RelativeGearingRelativegearingallowsyoutochangethegearratioon-the-fly.Themastermoveiscalculatedbasedonthemasterreferenceposition,whichisupdatedwhengearingisenabledandisupdatedeachtimeanewgearratioisloaded.Forexample,ifyouhaveagearingratioof2:1(slave:master),theslavemoves20countswhenthemasterdevicemoves10counts.

AbsoluteGearingAbsolutegearingbehavessimilarlytorelativegearinginthatwhengearingisenabled,theslaveaxisfollowsthemasteraxismovementasitisdefinedbythegearratio.Thedifferencebetweenrelativeandabsolutegearingisthatthereferencepositioncalculatedforthemasteraxisisupdatedonlywhengearingisenabled.Thisdifferenceisapparentwhenthegearratioisupdatedon-the-fly.Forexample,ifthegearratiois2:1,thecurrentmasterpositionis1010,thecurrentslavepositionis3020,andthegearratioischangedto3:1,theslaveaxisjumpsfrom3020to3030butthemasterpositionremainsthesame.

Changingagearratioon-the-flyduringabsolutegearingallowsyoutoquicklysynchronizetheslaveaxiswiththemasteraxis.

NoteWhenthegearratioischangedon-the-fly,theslaveaxismovesatfulltorquetothenewposition.

ElectronicGearingLabVIEWDiagramThefollowingblockdiagramdemonstratesusingNI-Motiontoperformelectronicgearingusinganencoderasthegearmaster.


1ConfigureGearMaster

5LoadVelocity 9StartMotion

2LoadGearRatio 6LoadAcceleration/Deceleration

10WaitforMoveComplete

3EnableGearingSingleAxis

7SetOperationMode 11EnableGearingSingleAxis

4Wait 8LoadTargetPosition 12MotionErrorHandler

ElectronicGearingC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)


u8slaveAxis;//Slaveaxisnumber

u8master;//Gearmaster


u16moveComplete;





///////////////////////////////

//SettheboardID

boardID=1;

//Settheaxisnumber

slaveAxis=1;

//Masterisencoder4

master=NIMC_ENCODER4;

////////////////////////////////

//--------------------------------------------------------

//Setupthegearingconfigurationfortheslaveaxis

//--------------------------------------------------------

//ConfigureGearMaster

err=flex_config_gear_master(boardID,slaveAxis,master);

CheckError;

//LoadGearRatio3:2

err=flex_load_gear_ratio(boardID,slaveAxis,NIMC_RELATIVE_GEARING,

3/*ratioNumerator*/,2/*ratioDenominator*/,0xFF);

CheckError;

//--------------------------------------------------------

//EnableGearingonslaveaxis

//--------------------------------------------------------

err=flex_enable_gearing_single_axis(boardID,slaveAxis,NIMC_TRUE);

CheckError;

//Waitfor5seconds

Sleep(5000);

//--------------------------------------------------------

//Setupthemoveparametersforthesuperimposedmove

//--------------------------------------------------------

//Settheoperationmodetorelative

err=flex_set_op_mode(boardID,slaveAxis,NIMC_RELATIVE_TO_CAPTURE);

CheckError;

//LoadVelocityincounts/s

err=flex_load_velocity(boardID,slaveAxis,10000,0xFF);

CheckError;

//LoadAccelerationandDecelerationincounts.sec^2

err=flex_load_acceleration(boardID,slaveAxis,NIMC_BOTH,100000,0xFF);

CheckError;

//Loadthetargetpositionfortheregistration(superimposed)move

err=flex_load_target_pos(boardID,slaveAxis,5000,0xFF);

CheckError;

//Startregistrationmoveontheslave

err=flex_start(boardID,slaveAxis,0);

CheckError;

err=flex_wait_for_move_complete(boardID,slaveAxis,0,

1000/*mstimeout*/,20/*mspollInterval*/,&moveComplete);

CheckError;

//--------------------------------------------------------

//DisableGearingonslaveaxis

//--------------------------------------------------------

err=flex_enable_gearing_single_axis(boardID,slaveAxis,NIMC_FALSE);

CheckError;


/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do

CammingElectroniccammingoperatessimilarlytoelectronicgearinginthatthemovedistanceofanaxisisproportionaltothemovedistanceofitsmasterdevice.Cammingdiffersfromgearinginhowthemaster/slaveratioishandledbythemotioncontroller.Gearingisusedinapplicationswhereaconstantgearvaluecreatesalinearslavepositionprofile,asshown.

Cammingcreatesamoreflexibleprofilebyusingmoremaster/slaveratios.Theseratiosarehandledautomaticallybythemotioncontroller,allowingpreciseswitchingofthegearratios,asshowninthefollowingfigure.Cammingisusedinapplicationswheretheslaveaxisfollowsanon-linearprofilefromamasterdevice.

ElectronicCammingAlgorithmThefollowingfigureshowsagenericelectronicgearingalgorithmapplicabletobothC/C++andLabVIEWcode.Similartogearing,inacammingapplication,aslaveaxiscanperformanymovewhencammingisenabled.Themoveprofileissuperimposedoverthecammingprofile.

CammingApplicationExampleAnexampleofamotioncontrolsystemthatcanbenefitfromtheflexibilityofelectroniccammingisweldingpartsastheytravelonaconveyorbelt.Thefollowingfigureshowsthattheweldingpointmovestothefirstposition,andthenweldsthematerialforacoupleofseconds.Becausetheconveyorbeltkeepsmovingataconstantrate,theweldingpointmustfollowthematerialatthesamespeedastheconveyorbeltduringtheweldprocess.Whentheweldingprocessisfinishedforoneitem,theweldingpointmustquicklyreturntoitsinitialpositionandtheprocessrepeats.

1Conveyorbelt2Movementofthewelderasitfollowstheobject,andthenreturnstotheinitialposition3Weldingpoint

Inthisapplication,themasterdeviceisthepositionencoderattachedtotheconveyorbelt,andtheslaveaxisistheactuatorthatmovestheweldingpoint.Theslaveaxisrepeatedlyperformsatwo-segmentmovement:

1. First,itfollowsthematerialwiththesamespeedastheconveyorbelt.

2. Next,itreturnstotheinitialpositionasthenextmaterialapproaches.

Eachsegmentofthemoveisrepresentedwithagearratiothatdictates

howfastandinwhichdirectiontheweldingpointismovingrelativetotheconveyorbelt.Thisapplicationrequirestheslaveaxistoswitchfromoneratiototheotheratthecorrectmasterposition,otherwisetheweldingprocessisnotrepeatable.Ifthisapplicationusedgearinginsteadofcamming,thelatency,ordelay,ofloadinganewgearratiomightcauseanaccumulationofpositionerrors.Whenacammingoperationisactive,theslaveaxisfollowsaprofilethatisestablishedusingalistofmasterandslavepositionspairs,calledthecammingtableandisloadedintoabufferforuseduringacammingoperation.Anexampleofacammingtableisshownbelow.Thefollowingfigureshowsthat,intheweldingexampledefinedpreviously,theconveyorbeltismovingat1,000counts/sandthepartstobeweldedare6,000countsapart.Toweldthepart,theweldingpointmustfollowthepartdowntheconveyorbeltfor2seconds.

Inthisweldingapplication,theslaveaxismustfollowthepartwiththesamevelocityastheconveyorbeltwhileweldingisinprogress.Becauseittakestwosecondstoweldeachpart,theweldingpointandconveyorbelthavebothmoved2,000countsbythetimetheweldingiscomplete.Thispartoftheweldingapplicationcreatesthefirstmovesegment.Forthesecondmovesegment,theweldingpointmustreturntoitsoriginalpositionsothatitcanweldthenextpartontheconveyorbelt.Tomovetheweldingpointtoitsoriginalpositionatthesametimethatthenextpartisinthecorrectpositionontheconveyorbelt,theweldingpointmusttravel2,000countsintheoppositedirectionoftheconveyorbeltat

halfthespeedthattheconveyorbeltistravelingat.Thefollowingfigureshowsthemoveprofileofthefirstandsecondmovesegments.

Thefollowingtableshowsthecammingtablethatcorrespondstothemoveprofileusedinthisexample.

Time(seconds)

MasterPosition(counts)

SlavePosition(counts) Ratio*

0 0 0 2 2000 2000 14 4000 1000 0.56 6000 0 0.5*Ratio=ΔSlaveDistance/ΔMasterDistance

Thecammingcycleis6,000countsandisdividedintoequallengthsegments.

TipBecausethecammingcycleis6,000counts,themastercyclemustalsobe6,000counts.

Eachrowofdatadefinesagearratio.Thecammingprofileisrepeatedafteracammingcycleiscompleted.Themasterpositionisalwaysinterpretedinsidethemodulusdefinedbythecammingcycle.

Forexample,initially,themasteraxismovesfrom0to1000.Thegearratiousedforthismoveis1:1becausethemasterpositionisinthe0to2000interval.Withagearratioof1:1,theslaveaxismovesatthesamespeedasthemasterdevicetoposition1000.

Asshown,themasterpositioninthisintervalisinsidethemodulus.

Ifthemasteraxismovestoposition2000,thegearratiodoesnotchangebecausethecurrentmasterpositionisstillinsidethe0to2000interval.

Whenthemasteraxismovestoposition4,000,thegearratiochangesto0.5.Theslaveaxistravelshalfthedistancethatthemasteraxistravels,andittravelsintheoppositedirection.Whenthemasterreachesposition6000,theslaveaxismovesbacktheoriginalposition,andthecammingcyclebeginsagain.

SlaveOffsetInsomecammingapplications,theslaveaxismightbeginandendthecammingcycleatdifferentpositions,asshowninthefollowingtable.

MasterPosition(counts) SlavePosition(counts)0 02000 20004000 10006000 500

Thefollowingfigureshowsthat,afterthreecammingcycles,theslaveaxisendpositionis500countsawayfromthestartingposition(0)withtheslaveoffset,andthatwithouttheslaveoffset,theslaveaxisendpositionis1500countsawayfromthestartingposition(0).Withaslaveoffsetof500,theslaveaxistraversesthepositionsspecifiedinthecammingtable,butitdoesnotmaintainthecammingratio.

MasterOffsetIfthematerialandweldingpointarenotinitiallyaligned,asshown,themasteroffsetmustbeappliedtoconsiderthepositiondifference.

Withoutthemasteroffset,themasterdevicepositionisalreadyinsidethefirstintervalassoonasthefirstmaterialpassestheweldingpoint.Thefollowingfigureshowsthatthemastercycleintervalsareoffsetby50counts.Themasterintervalisshiftedfrom0,2,000,4,000,and6,000to50,2,050,4,050,and6,050.

Thefollowingfigureshowsthecammingprofileusedfortheapplicationportrayedinthepreviousfigures.

ElectronicCammingLabVIEWDiagramThefollowingblockdiagramdemonstratesusingNI-Motiontoperformelectroniccamming.


1ConfigureCammingMaster

6SetOperationMode

11EnableCammingSingleAxis

2ConfigureBuffer 7LoadMoveConstraint

12ClearBuffer

3WriteBuffer 8LoadTargetPosition


4EnableCammingSingleAxis

9StartMotion

5WaitinaSequenceStructure

10WaitforMoveComplete

ElectronicCammingC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//////////////////////////////////////////////////////////////////////

//MainFunction

voidmain(void)

//Locals

u8boardID;//BoardIDasassignedbyMAX

f64bufferInterval=0;//Ignored

//Masteraxisinformation

u8masterAxis;//MasteraxisID

i32targetPos;//Positiontomoveto

f64velocity;//Velocitylimitforthismove

f64camCycle=70000;//Positioncycletorepeatthecammingprocess

NIMC_DATAdata;//Genericdatastructure

i32masterPosition;//Currentmasterposition

u16masterStatus;//Currentmasterstatus

//Slaveaxisinformation

u8slaveAxis;//SlaveaxisID

u8buffer;//Buffertocontainthecamtable

i32positionArr[]=0,10000,40000,45000,45000,40000,10000,0;//

u32positionSize=sizeof(positionArr)/sizeof(i32);//Numberofpositionsinthearray

i32slavePosition;//Currentslaveposition

//Forerrorhandling

u16csr;//Communicationstatus

u16commandID;//CommandIDthatcausestheerror

u16resourceID;//ResourceIDthatissetonthefailedcommand

i32errorCode;//Errorcodefromthecontroller

i32scanVar;//Scanvariabletoreadinvaluesnotsupported

//bythescanffunction

//GettheboardID

printf("EntertheboardID:");


boardID=(u8)scanVar;

//Getmasteraxisinformation

printf("\nEnterinformationaboutthemasteraxis...\n");

printf("AxisID:");


masterAxis=(u8)scanVar;

printf("Targetposition:");

scanf("%d",&targetPos);

printf("Velocitylimit:");

scanf("%lf",&velocity);

//GettheslaveAxis

printf("\nEnterinformationabouttheslaveaxis...\n");

printf("AxisID:");


slaveAxis=(u8)scanVar;

printf("BufferID:");


buffer=(u8)scanVar;

//Configurethecammaster&mastercycle

err=flex_configure_camming_master(boardID,slaveAxis,masterAxis,camCycle);

CheckError;

//Configurethecamtable

err=flex_configure_buffer(boardID,buffer,slaveAxis,

NIMC_CAMMING_POSITION,

positionSize,positionSize,

TRUE,bufferInterval,&bufferInterval);

CheckError;

//Writethedatatothebuffer

err=flex_write_buffer(boardID,buffer,positionSize,

NIMC_REGENERATION_NO_CHANGE,

positionArr,0xFF);

CheckError;

//Enablecammingimmediately

err=flex_enable_camming_single_axis(boardID,slaveAxis,TRUE,-1.0);

CheckError;

//Settoabsolutemode

err=flex_set_op_mode(boardID,masterAxis,NIMC_ABSOLUTE_POSITION);

CheckError;

//Setthemaximumvelocity

data.doubleData=velocity;

err=flex_load_move_constraint(boardID,masterAxis,

TnimcMoveConstraintVelocity,&data);

CheckError;

//Setthetargetposition

err=flex_load_target_pos(boardID,masterAxis,targetPos,0xFF);

CheckError;

//Startthemasteraxismovement

err=flex_start(boardID,masterAxis,0x0);

CheckError;

//Keeprunninguntilthemastercompletesorthere'samodalerror

do

Sleep(100);

//Getboththemasterandtheslavecurrentpositions.

err=flex_read_pos_rtn(boardID,masterAxis,&masterPosition);

CheckError;

err=flex_read_pos_rtn(boardID,slaveAxis,&slavePosition);

CheckError;

//Displaythemasterandtheslavecurrentpositions.

printf("Axis%d(master)positionis%d,Axis%d(slave)positionis%d.\r",

masterAxis,masterPosition,slaveAxis,slavePosition);

//Readcurrentmastertrajectorystatus

err=flex_read_axis_status_rtn(boardID,masterAxis,&masterStatus);

CheckError;

//Checkformodalerror


CheckError;

while(!(masterStatus&NIMC_MOVE_COMPLETE_BIT)&&

!(csr&NIMC_MODAL_ERROR_MSG));

/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//


//Disablecamming

flex_enable_camming_single_axis(boardID,slaveAxis,FALSE,-1.0);

//Clear(delete)thebuffer

flex_clear_buffer(boardID,buffer);

//Makesurethemasterisnotrunning

flex_stop(boardID,masterAxis,0x0);



do


AcquiringTime-SampledPositionandVelocityDataNImotioncontrollerscanacquireabufferofpositionandvelocitydatathatisfirmware-timed.Afteryoucommandthemotioncontrollertoacquirepositionandvelocitydata,aseparateacquiredatataskiscreatedinthereal-timeoperatingsystemthatreadstime-sampledpositionandvelocitydataintoaFIFObufferonthemotioncontroller.Youcanreaddatainfromthisbufferasynchronouslyfromthehostcomputer,asshowninthefollowingfigure.

Theacquiredatataskhashigherprioritythananyonboardprogramsorhousekeepingtasks,butithasalowerprioritythantheI/Oreactionandhostcommunicationtasks.Toachievethebestpossibleperformance,keephostcommunicationstoaminimumwhenacquiringdata.TheFIFObufferisofafixedsizethatcanaccommodate4,096samplesforoneaxis.Onesampleconsistsofpositiondata,incountsorsteps,andvelocitydata,incounts/sorsteps/s.Asyouincreasethenumberofaxesfromwhichyouareacquiringdata,youalsodecreasethetotalnumberofsamplesyoucanacquireperaxis.Forexample,youcanacquireupto1,024samplesperaxisforfouraxes.Youalsocanvarythetimeperiodbetweenacquiredsamplesfrom3msto65,535ms.

AcquireDataAlgorithmThefollowingfigureshowsagenericalgorithmapplicabletobothC/C++andLabVIEWcode.

Thedatamustbereadonesampleatatime.Afour-axissampleusesthefollowingpatternforreturningthedata.

Axis1positionAxis1velocity




Ifyourequest1,024samples,youmustreadeachofthe1,024samplesindividually.

AcquireDataLabVIEWDiagramThefollowingblockdiagramdemonstratesusingNI-Motiontoacquiresdatafortwoaxes,200samples,andthreemillisecondsapart.


1AcquireTrajectoryData 3MotionErrorHandler2ReadTrajectoryData

AcquireDataC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)



i32i;

u16axisMap;//Bitmapofaxesforwhichdataisrequested

i32axis1Positions[200];//Arraytostorethepositions(1)

i32axis1Velocities[200];//Arraytostorevelocities(1)

i32axis2Positions[200];//Arraytostorethepositions(2)

i32axis2Velocities[200];//Arraytostorevelocities(2)

u16numSamples=200;//Numberofsamples

i32returnData[4];//Needsizeof4for2axesworthofdata





///////////////////////////////

//SettheboardID

boardID=1;

//Axeswhosedataneedstobeacquired

axisMap=((1<<1)|(1<<2));//Axis1andaxis2

////////////////////////////////

err=flex_acquire_trajectory_data(boardID,axisMap,numSamples,3/*mstimeperiod*/);

CheckError;

for(i=0;i<numSamples;i++)

Sleep(10);//Checkevery10msandgivetimeforthedata

//tobecopiedtoonboardFIFO

//Readthetrajectorydata

err=flex_read_trajectory_data_rtn(boardID,returnData);

CheckError;

//Twoaxesworthofdataisreadeverysample

axis1Positions[i]=returnData[0];

axis1Velocities[i]=returnData[1];

axis2Positions[i]=returnData[2];

axis2Velocities[i]=returnData[3];


/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











SynchronizationYoucansynchronizeNImotioncontrollerswithNIdataandimageacquisitiondevicesusingbreakpointsandhigh-speedcaptures.Thefollowingfigureillustratesanexpandedviewofthetopicscoveredinthissection.

*Breakpointscauseadigitaloutputtochangestatewhenaspecifiedpositionisreachedbyanencoder.BreakpointsarenotsupportedbytheNISoftMotionController.**Ahigh-speedcapturerecordsthepositionofanencoderwhenadigitallineisusedasatrigger.High-speedcapturesarenotsupportedbytheNISoftMotionController.

NoteIfyouareusingRTSItoconnectyourmotioncontrollertoaNationalInstrumentsdataorimageacquisitiondevice,beawarethattheNISoftMotionControllerdoesnotsupportRTSI.

TimingandtriggeringwithNI-Motionisalwaysrelatedtoeitherpositionorvelocity.Synchronizingpositionandvelocityinformationwiththeexternalworldallowsyoutocoordinatemeasurementswithmoves.YoucanprogramthemotioncontrollertotriggeranotherdeviceatspecifiedpositionsusingRTSIorapinontheMotionI/Oconnector.This

functionalityiscalledbreakpoints,whicharedividedintoabsolutebreakpoints,relativepositionbreakpoints,andperiodicallyoccurringbreakpoints.Insomecases,itmaybenecessarytosynchronizepositionwithsomemeasurementoccurringexternaltothemotioncontroller.Forexample,youmightbealigningtwofiberopticcables,inwhichcasethemaximumopticalpowerneedstocorrespondwiththealignmentposition.Toalignthefibers,theexternaldevicethatisrecordingtheopticalpowermusttriggerthemotioncontrollersothatpositionsandopticalpowermeasurementscanbesynchronizedandanalyzed.Thisfunctionalityisknownashigh-speedcaptureortriggerinputs.ThemotioncontrollercanbetriggeredbyanotherdeviceusingRTSIorexternallyusingapinontheMotionI/Oconnector.Whentriggered,themotioncontrollercanlatchthecurrentpositionoftheencoder,whichcanbereadandrecorded.ThefollowingtableshowstheavailabilityofbreakpointmodesoneachNImotioncontroller.

BreakpointMode NI7350 NI7340,NI7330,andNI7390Absolute* Y Y

Relative* Y Y

Periodic Y NModulus N YBuffered Y N*AvailableinbufferedandsingleoperationforNI7350andinsingleoperationonlyforallothercontrollers

AbsoluteBreakpointsAbsolutepositionbreakpointsallowyoutotriggerexternalactivitiesasthemotorsreachspecifiedpositions.Forexample,ifyouneedtouseanimageacquisitiondevicetocaptureanimagefromacertainpositionwhilethedeviceundertestisincontinuousmotion,themotioncontrollermustbeabletotriggertheimageacquisitiondeviceasitreachesthosepositions.Thecurrentpositioniscontinuouslycomparedagainstthespecifiedbreakpointpositionbytheencodercircuitrytoproducealatencyoflessthan100ns.Afterabreakpointtriggers,youmustre-enableitforthebreakpointtoworkagain.Incertaincases,suchasbufferedandperiodicbreakpoints,themotioncontrollerautomaticallyre-enablesthebreakpoints.Theimplementationforabsolutebreakpointsisdividedintothebufferedbreakpointandsinglepositionbreakpointmethods.

NoteAllbreakpointscanbeaffectedbyjitterinthemotioncontrolsystem.Forexample,ifyouhaveaverysmallbreakpointwindow,thejitterinthemotioncontrolsystemcouldcausethepositiontochangeenoughtoreachthebreakpointwhenabreakpointisnotintended.Increasethesizeofthebreakpointwindowtocompensateforsystemjitter.

BufferedBreakpoints(NI7350only)Insteadofenablingbreakpointsinyourapplicationatthesoftwarelevel,youcancreateabufferofbreakpointsthatyoucanpre-loadintothemotioncontroller.Themotioncontrollerautomaticallyarmsthenextbreakpointinthebufferwhentheprecedingbreakpointtriggers.Therefore,enablingbreakpointsoccursonafirmware-timedbasis,whichenablesyoutouseahigherbandwidth.

BufferedBreakpointAlgorithmThefollowingshowsthebasicalgorithmforimplementingbufferedbreakpointsapplicabletobothC/C++andLabVIEWcode.

BufferedBreakpointLabVIEWDiagramThefollowingblockdiagramdemonstratesusingNI-Motiontocompleteablendedmove.


1ConfigureBuffer 4EnableBreakpointOutput

6ClearBuffer

2WriteBuffer 5CheckBuffer 7MotionErrorHandler

3ConfigureBreakpoint

BufferedBreakpointC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)

//Resourcevariables

u8boardID=1;//Boardidentificationnumber

u8axis=NIMC_AXIS1;//Axisnumber

u8buffer=1;//Buffernumber

//Modalerrorhandlingvariables




u16csr=0;//Communicationstatus

//Bufferresources

i32breakpointPositions[]=1000,1100,1200,1300,1400,1500,1600;

u16numberOfPoints=7;//Numberofbreakpoints

f64actualInterval;//Requiredinthefunctioncallbutnotbeingused

f64requestedInterval=10.0;//Requiredinthefunctioncallbutnotbeingused

u32backLog;//Numberofspaceavailableinbuffer

u16bufferState;//Bufferstate

u32pointsDone;//Numberofbreakpointsdoneorconsumed

//Configurethebufferforbufferedbreakpoint

err=flex_configure_buffer(boardID,buffer,axis,NIMC_BREAKPOINT_DATA,

numberOfPoints,numberOfPoints,NIMC_TRUE,

requestedInterval,&actualInterval);

CheckError;

//Writethebreakpointpositiontothebuffer

err=flex_write_buffer(boardID,buffer,numberOfPoints,

NIMC_REGENERATION_NO_CHANGE,breakpointPositions,0xFF);

CheckError;

//Configurethebreakpointtobebufferedbreakpoint

err=flex_configure_breakpoint(boardID,axis,NIMC_ABSOLUTE_BREAKPOINT,

NIMC_PULSE_BREAKPOINT,NIMC_OPERATION_BUFFERED);

CheckError;

//Enablethebreakpoint

err=flex_enable_breakpoint(boardID,axis,NIMC_TRUE);

CheckError;

//Pollthestatusofthebuffer,ifyoumorebreakpointpositions

//towrite,insertflex_write_buffercallhere.

do

//Checkthebufferstatus

err=flex_check_buffer_rtn(boardID,buffer,

&backLog,&bufferState,&pointsDone);

CheckError;

Sleep(50);

while((pointsDone!=numberOfPoints)||

(bufferState!=NIMC_BUFFER_DONE));

//Clearthebuffer

err=flex_clear_buffer(boardID,buffer);

CheckError;

return;

/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











SinglePositionBreakpointsSinglepositionbreakpointsexecuteonebreakpointperenabling.

SinglePositionBreakpointAlgorithmThefollowingfiguresshowsthebasicalgorithmforimplementingsinglepositionbreakpointsapplicabletobothC/C++andLabVIEWcode.

SinglePositionBreakpointLabVIEWDiagramThefollowingblockdiagramsdemonstrateusingNI-Motiontoprogramasinglepositionbreakpoint,bothwithandwithoutRTSI.



3EnableBreakpointOutput

5MotionErrorHandler

2LoadBreakpointPosition

4ReadperAxisStatus

ThefollowingfigureshowshowtoroutethisbreakpointusingRTSI.

1SelectSignal 3LoadBreakpointPosition

5ReadperAxisStatus



6MotionErrorHandler

AfterthebreakpointisroutedthroughRTSI,thetriggerappearsonboth

theRTSIlineandthebreakpointlineontheMotionI/Oconnector.

SinglePositionBreakpointC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)


u8axis;//Axisnumber



i32breakpointPosition[3]=10000,15000,20000;

i32i;





///////////////////////////////

//SettheboardID

boardID=1;

//Settheaxisnumber

axis=1;

////////////////////////////////

//Routebreakpoint1toRTSIline1

err=flex_select_signal(boardID,NIMC_RTSI1/*destination*/,NIMC_BREAKPOINT1/*source*/);

CheckError;

//ConfigureBreakpoint

err=flex_configure_breakpoint(boardID,axis,NIMC_ABSOLUTE_BREAKPOINT,NIMC_SET_BREAKPOINT,0);

CheckError;

for(i=0;i<3;i++)

//LoadBreakpointPosition-positionatwhichbreakpointshouldoccur

err=flex_load_pos_bp(boardID,axis,breakpointPosition[i],0xFF);

CheckError;

//Enablethebreakpointonaxis1


CheckError;

do

//Checkthebreakpointstatus


CheckError;



CheckError;

//Checkformodalerrors



CheckError;


while(!(axisStatus&NIMC_POS_BREAKPOINT_BIT));//Waitforbreakpointtobetriggered


/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











RelativePositionBreakpointsRelativepositionbreakpointstriggereventsbasedonachangeinpositionrelativetothepositionatwhichthebreakpointwasenabled.Insteadofkeepingtrackofabsolutepositionsandthecurrentposition,youcanuserelativebreakpointstospecifythebreakpointrelativetothepositionwherethebreakpointisenabled.Forexample,ifyouarecreatingamotioncontrolsystemtocontrolthetwo-dimensionalmovementofamicroscope,youmightuserelativepositionbreakpointstomovethemicroscopeaspecificdistanceinadirection,andthenhitabreakpointthattriggersacamerasnap.Therelativebreakpointisusefulinthisexamplebecausethecurrentpositionisnotimportant.Theapplicationmustmovetheaxisaspecificnumberofcountsfromwhereveritis,andthengenerateabreakpoint.


RelativePositionBreakpointsAlgorithmThefollowingfigureshowsthebasicalgorithmforrelativebreakpointsapplicabletobothC/C++andLabVIEWcode.

Noticethatrelativebreakpointsarenotidealforperiodicbreakpoints.Thereisalatencybetweenthetimeabreakpointgeneratesandisre-enabled.Iftheaxisismovingatsufficientvelocity,thebreakpointre-enablesonlyaftertheaxishasmovedslightly.Becausearelativebreakpointgeneratesrelativetothepositiontheaxiswasinwhenthebreakpointwasenabled,thelatencybetweengenerationandre-enablingcancauseadditionalcountsbetweenbreakpoints.Forexample,theactualbreakpointsmightoccuratpositions5,000;10,003;15,006;and20,012.Inthisexample,theaxismovesthreecountsbetweenabreakpointandthesubsequentre-enabling.Forexactdistancesbetweenbreakpointsathighspeeds,useBufferedBreakpoints(NI7350only)orPeriodicallyOccurringBreakpoints.

RelativePositionBreakpointsLabVIEWDiagramInthisexample,abreakpointgeneratesandthenisre-enabled5,000countsfromwherethemovestartsusingRTSI.Thefollowingcodeexamplesaredesignedtoillustratetherelativebreakpointalgorithmonly.Theseexamplesarenotcomplete.



5ReadperAxisStatus



6MotionErrorHandler

RelativePositionBreakpointsC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)


u8axis;//Axisnumber



i32breakpointPosition=5000;





///////////////////////////////

//SettheboardID

boardID=1;

//Settheaxisnumber

axis=1;

////////////////////////////////



CheckError;


err=flex_configure_breakpoint(boardID,axis,NIMC_RELATIVE_BREAKPOINT,NIMC_SET_BREAKPOINT,0);

CheckError;


err=flex_load_pos_bp(boardID,axis,breakpointPosition,0xFF);

CheckError;

for(;;)



CheckError;

do

//Checkthebreakpointstatus


CheckError;



CheckError;




CheckError;




/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











PeriodicallyOccurringBreakpointsNI-Motionallowsyoutoprogramthemotioncontrollertogeneratemultiplebreakpointsatfixedandexactintervals,regardlessofthedirectionoftravelorvelocity.TherearetwowaystocreateperiodicallyoccurringbreakpointsusingNI-Motionfunctions,dependingonwhichmotioncontrolleryouhave.FortheNI7350controller,useperiodicbreakpoints.ForNI7330,NI7340,andNI7390controllers,usemodulobreakpoints.


PeriodicBreakpoints(NI7350only)Periodicbreakpointsrequirethatyouspecifyaninitialbreakpointandanongoingrepeatperiod.Whenenabled,theperiodicbreakpointsbeginwhentheinitialbreakpointoccurs.Fromthenon,anewbreakpointoccurseachtimetheaxismovesadistanceequaltotherepeatperiod,withnore-enablingrequired.Forexample,ifanaxisisenabledatpositionzero,theinitialbreakpointissetforposition100,andthebreakpointperiodissetat1,000,thentheaxisbehavesasshowninthefollowingfigure.

PeriodicBreakpointAlgorithmThefollowingfigureshowsthebasicalgorithmforperiodicbreakpointsapplicabletobothC/C++andLabVIEWcode.

PeriodicBreakpointLabVIEWDiagramThefollowingblockdiagramdemonstratesusingNI-Motiontogenerateaperiodicbreakpointoutput.




7ReadperAxisStatus


5LoadTargetPosition 8MotionErrorHandler

3LoadBreakpointModulus

6StartMotion

PeriodicBreakpointC/C++CodeThefollowingsectionincludesC/C++codeforexecutingahigh-speedcapture,aswellasusingRTSItoexecuteahigh-speedcapture.Thefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)


u8axis;//Axis

u16csr=0;//CommunicationstatusRegister

u8profileStatus;//ProfileCompleteStatus

u8bpStatus;//BreakpointfoundStatus

i32bpPos;//BreakpointPosition

i32bpPer;//BreakpointPeriod

i32targetPos;//TargetPosition

i32currentPos;//CurrentPosition

u16axisStatus;//Statusoftheaxis





//GettheboardID

printf("EntertheBoardID:");

scanf("%u",&boardID);

//Gettheaxisnumber

printf("Enteraaxisnumber:");

scanf("%u",&axis);

//GettheTargetPosition

printf("Enteratargetposition:");

scanf("%ld",&targetPos);

//GettheBreakpointPosition

printf("Enterabreakpointposition:");

scanf("%ld",&bpPos);

//GettheBreakpointPeriod

printf("Enterabreakpointperiod:");

scanf("%ld",&bpPer);

//Configurethebreakpointtobeabsolute

err=flex_configure_breakpoint(boardID,axis,NIMC_PERIODIC_BREAKPOINT,NIMC_NO_CHANGE,0);

CheckError;

//Loadthepositiontostartbreakpoints

err=flex_load_pos_bp(boardID,axis,bpPos,0xFF);

CheckError;

//SetthePeriod

err=flex_load_bp_modulus(boardID,axis,bpPer,0xFF);

CheckError;

//Enablethebreakpoint


CheckError;

//Loadatargetposition

err=flex_load_target_pos(boardID,axis,targetPos,0xFF);

CheckError;

//Startthemotion


CheckError;

printf("\n");

do

//Readtheaxisstatus


CheckError;

err=flex_read_pos_rtn(boardID,axis,&currentPos);

CheckError;

//Checkthebreakpointbit

bpStatus=!((axisStatus&NIMC_POS_BREAKPOINT_BIT)==0);

//Checktheprofilecompletebit

profileStatus=!((axisStatus&NIMC_PROFILE_COMPLETE_BIT)==0);

printf("CurrentPosition=%10dBreakpointStatus=%dProfileComplete=%d\r",currentPos,bpStatus,profileStatus);



CheckError;



flex_stop_motion(boardID,NIMC_VECTOR_SPACE1,NIMC_DECEL_STOP,0);//


CheckError;

while(!profileStatus);

printf("\nFinished.\n");


/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











ModuloBreakpoints(NI7330,NI7340,andNI7390only)Modulobreakpointsuseabreakpointwindow,whichdefinesanareaaroundthecurrentposition.Thetwobreakpointsaroundthecurrentpositionarealwaysenabled.Thebreakpointmoduluscreatesarepeatperiodforthebreakpoints,andthebreakpointpositionistheoffsetfromabsolutezero.Forexample,tocreateabreakpointevery500counts,settherepeatperiodto500andthebreakpointpositionto0.Ifthebreakpointisenabledwhentheaxisisat710,thebreakpointsat1000and500arebotharmed,asshowninthefollowingfigure.

Asanotherexample,ifyousetthebreakpointrepeatperiodtobe2000countsandtheoffsettobe500,breakpointsoccurat4500,2500,500,1500,3500.Ifthebreakpointisenabledwhentheaxisisat2210,thebreakpointsat1500and3500arebotharmed,asshowninthefollowingfigure.

Eachtimeabreakpointoccurs,re-enableittoloadthenextbreakpoint.

ModuloBreakpointsAlgorithmThefollowingfigureshowsthebasicalgorithmformodulobreakpointsapplicabletobothC/C++andLabVIEWcode.

ModuloBreakpointsLabVIEWDiagramThefollowingblockdiagramsdemonstrateusingNI-MotiontogenerateamodulobreakpointsbothwithandwithoutRTSI.




5ReadperAxisStatus



6MotionErrorHandler


6ReadperAxisStatus



7MotionErrorHandler


ModuloBreakpointsC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)


u8axis;//Axisnumber







///////////////////////////////

//SettheboardID

boardID=1;

//Settheaxisnumber

axis=1;

////////////////////////////////



CheckError;


err=flex_configure_breakpoint(boardID,axis,NIMC_MODULO_BREAKPOINT,NIMC_SET_BREAKPOINT,0);

CheckError;

//LoadBreakpointModulus-repeatperiod

err=flex_load_bp_modulus(boardID,axis,500,0xFF);

CheckError;


//everymodulo

err=flex_load_pos_bp(boardID,axis,0,0xFF);

CheckError;

for(;;)



CheckError;

do



CheckError;



CheckError;




CheckError;




/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











ConfiguringtheBreakpointPulseWidth(NI7350only)OnNI7350devicesyoucanconfigureacustomizedpulsewidthforbreakpoints(positioncompareoutputs)totriggerdevicesthathavespecificminimumactivepulserequirements.Thedefaultbreakpointpulsewidthis200ns.YoucanuseMAXortheWriteCaptureCompareDataVIorfunctiontosetapulsewidthofbetween1µsand65,535µs.Onabreakpointevent,thebreakpointsignalisactivefortheconfiguredpulsewidth,asshowninthefollowingfigure.

NoteAbreakpointacrossRTSIalwaysgeneratesanactivehighpulseof200nsduration.

CautionThebreakpointfrequencydependsonthevelocityanddistancebetweenbreakpointsandislimitedbythepulsewidth.Thebreakpointfrequencymustmeetthefollowingrequirementsforcorrectoperation.

NI-MotionCReferenceHelp.chm::/nimcWriteCaptureCompareData.html

BreakpointFrequencyRequirementsThebreakpointpulsemustnotoverlapwiththenextbreakpointevent.Ifthebreakpointpulseoverlapswiththenextbreakpointevent,breakpointgenerationisstoppedandthebreakpointisdisabled.Torecoverfromthissituationchangethepulsewidth,velocity,ordistancebetweenbreakpoints.Inaddition,thebreakpointfrequencycannotbegreaterthanthemaximumvalueallowedforthespecifiedbreakpointtype.Therefore,thebreakpointfrequency,inhertz,atthespecifiedpulsewidth,inseconds,mustconformtomustconformtothefollowingtwoconditions:

AND

PositionCompare(Breakpoint)OutputType MaximumFrequencySingle 150HzBuffered,PIDrateof62.5µsto250µs

2kHz

Buffered,PIDrategreaterthan250µs

1kHz

Periodic 4MHz

High-SpeedCaptureSomemotioncontrolapplicationsrequirethatyouexecuteamoveandrecordthelocationswhereexternaltriggershappen.Toaccomplishthis,youmustusethehigh-speedcapturefunctionalityofNImotioncontrollers.Theimplementationforhigh-speedcaptureisdividedintothebuffered(NI7350controllersonly)andnon-bufferedhigh-speedcapturemethods.

High-SpeedCaptureAlgorithmThefollowingfigureshowsthebasicalgorithmforhigh-speedcapturesapplicabletobothC/C++andLabVIEWcode.

BufferedHigh-SpeedCapture(NI7350only)Bufferedhigh-speedcaptureletsyoucreateabufferthatholdscapturedpositionsthatyoucanreadasynchronouslyfromthemotioncontroller.Themotioncontrollerautomaticallyarmsthenexthigh-speedcapture,andwritesthecapturedhigh-speeddataintoitsonboardbuffer.Theenablingofhigh-speedcaptureoccursonafirmware-timedbasis,whichprovidesbetterfrequencythanthenon-bufferedhigh-speedcapturemethod.

BufferedHigh-SpeedCaptureAlgorithmThefollowingfigureshowsthebasicalgorithmforbufferedhigh-speedcapturesapplicabletobothC/C++andLabVIEWcode.

BufferedHigh-SpeedCaptureLabVIEWDiagramThefollowingblockdiagramdemonstratesusingNI-Motiontoperformabufferedhigh-speedcapture.


1ConfigureBuffer 4CheckBuffer

6ClearBuffer

2ConfigureHigh-SpeedCapture

5ReadBuffer

7MotionErrorHandler

3EnableHigh-SpeedCapture

BufferedHigh-SpeedCaptureC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)


u8axis;//Axisnumber



u32totalPoints=100;//Thenumberofhighspeedcapturetoacquire

i32capturedPositions[100];//Arraytostorethecapturedpositions


u32backlog;//Indicatestheavailablespaceforcapturedpositions



u32currentDataPoint=0;//Indicatesthenextpointstobereadfromthebuffer

i32*readBuffer=NULL;//Thetemporaryarraythatiscreatedtoreadcapturedpositions

u32i;





///////////////////////////////

//SettheboardID

boardID=1;

//Settheaxisnumber

axis=NIMC_AXIS1;

////////////////////////////////



err=flex_configure_buffer(boardID,1/*buffernumber*/,axis,NIMC_HS_CAPTURE_READBACK,bufferSize,

totalPoints,NIMC_TRUE,10,&actualInterval);

CheckError;

//ConfigureHighSpeedCapture

err=flex_configure_hs_capture(boardID,axis,NIMC_HS_LOW_TO_HIGH_EDGE,NIMC_OPERATION_BUFFERED);

CheckError;

//Enablethehighspeedcaptureonaxis

err=flex_enable_hs_capture(boardID,axis,NIMC_TRUE);

CheckError;

do


CheckError;

//Checkbacklogforcapturedpositioninbuffer

if(backlog>0)

readBuffer=(i32*)malloc(sizeof(i32)*backlog);

//Ifcapturedpositionavailableinthebuffer,readthecapturedpositionfromthebuffer

err=flex_read_buffer_rtn(boardID,1/*buffernumber*/,backlog,readBuffer);


if(currentDataPoint>totalPoints)break;

capturedPositions[currentDataPoint]=readBuffer[i];

printf("capturepos%d\n",capturedPositions[currentDataPoint]);

currentDataPoint++;

free(readBuffer);

readBuffer=NULL;

CheckError;




CheckError;




CheckError;


while(bufferState!=NIMC_BUFFER_DONE);



CheckError;


/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











Non-BufferedHigh-SpeedCaptureNon-bufferedhigh-speedcaptureallowsyoutoconfigureasinglehigh-speedcaptureevent.Formultiplehigh-speedcaptures,youmustre-enablethehigh-speedcaptureeachtimeittriggers.

High-SpeedCaptureAlgorithmThefollowingfigureshowsthebasicalgorithmforhigh-speedcapturesapplicabletobothC/C++andLabVIEWcode.

High-SpeedCaptureLabVIEWDiagramThefollowingblockdiagramsdemonstrateusingNI-Motiontoperformahigh-speedcapture,bothwithandwithoutRTSI.


1ConfigureHigh-SpeedCapture 3ReadperAxisStatus2EnableHigh-SpeedCapture 4ReadCapturedPosition

Totriggerthehigh-speedcapturefromaRTSIline,settheDestinationparameterinSelectSignaltoHighSpeedCapture1,asshowninthefollowingblockdiagram.

1SelectSignal 3EnableHigh-SpeedCapture

5ReadCapturedPosition

2ConfigureHigh-SpeedCapture

4ReadperAxisStatus

High-SpeedCaptureC/C++CodeThefollowingsectionincludesC/C++codeforexecutingahigh-speedcapture,aswellasusingRTSItoexecuteahigh-speedcapture.Thefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)


u8axis;//Axisnumber



i32capturedPositions[6];//Arraytostorethecapturedpositions

i32i;





///////////////////////////////

//SettheboardID

boardID=1;

//Settheaxisnumber

axis=1;

////////////////////////////////


err=flex_select_signal(boardID,NIMC_HS_CAPTURE1/*destination*/,NIMC_RTSI1/*source*/);

CheckError;

//ConfigureHighSpeedCapture

err=flex_configure_hs_capture(boardID,axis,NIMC_HS_LOW_TO_HIGH_EDGE,0);

CheckError;

for(i=0;i<6;i++)

//Enablethehighspeedcaptureonaxis

err=flex_enable_hs_capture(boardID,axis,NIMC_TRUE);

CheckError;

do

//Checkthehighspeedcapturestatus


CheckError;



CheckError;




CheckError;


while(!(axisStatus&NIMC_HIGH_SPEED_CAPTURE_BIT));//Waitforhighspeedcapturetobetriggered

err=flex_read_cap_pos_rtn(boardID,axis,&capturedPositions[i]);

CheckError;


/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











Real-TimeSystemIntegrationBus(RTSI)RTSIisadedicatedhigh-speeddigitalbusdesignedtofacilitatesystemintegrationbylow-level,high-speed,real-timecommunicationbetweenNationalInstrumentsdevices.Manyapplications,suchasscanningandalignment,synchronizemeasurementsmadewithdataandimageacquisitiondeviceswithpositionandvelocity.Thissynchronizationrequireshighspeedswithlowlatencies.UsingRTSI,theNImotioncontrollercansharehigh-speeddigitalsignalswithNIdataacquisitiondevices,NIimageacquisitiondevices,digitalI/O,orotherNImotiondeviceswithnoexternalcablingandwithoutconsumingbandwidthonthehostbus.TheRTSIbusalsohasbuilt-inswitching,soyoucanroutesignalstoandfromthebuson-the-flyusingsoftware.Inadditiontothebreakpointandhighspeedcapturesignals,youcanrouteencoderpulsesovertheRTSIlines,whichservesasawaytotriggeranexternaldeviceoneverychangeintheencoderchannels.YoucanroutephaseA,phaseB,andtheindexpulseoftheencoderoverRTSI.YoualsocancreateasoftwaretriggerbywritingtotheRTSIlinesdirectlyfromsoftware.YoucanroutepositionbreakpointsandencoderpulsesusingtheRTSIbustotriggerotherdevices.Youalsocanconfiguredataandimageacquisitiondevicestotriggerhigh-speedcapturesontheNImotioncontrollersusingtheRTSIbus.

RTSIImplementationontheMotionControllerYoucanconfigureanonboardbufferonthemotioncontrollerandusethebufferedhigh-speedcaptureorbreakpointfunctionalitytosynchronizethemotionapplicationwithdataorimageacquisition.Asshowninthefollowingfigure,theI/Oreactiontaskautomaticallyre-enablesthebreakpointsorhigh-speedcapturesontheNI7350motioncontroller.OnNI7340motioncontrollers,youmustwriteanonboardprogramorusethehosttoperformthesamere-enablingtasks.

RTSIInputandOutputThefollowingsectionsexplaintheusageofRTSIforinputandoutputsignals.

PositionBreakpointsUsingRTSIYoucanusetheSelectSignalVIorfunctiontoroutepositionbreakpointsusingoneoftheRTSIlines.Inthiscase,themotioncontrollertriggerstheexternaldeviceatagivenposition,asshown.

NoteAbreakpointacrossRTSIalwaysgeneratesanactivehighpulseof200nsduration.

NI-MotionCReferenceHelp.chm::/flex_select_signal.html

EncoderPulsesUsingRTSIYoumayneedtotriggertheexternaldevicetoacquiredataeveryencoderphaseoronanencoderindexpulse,asshown.

SoftwareTriggerUsingRTSIYoucanusetheSetI/OPortMOMOVIorfunctiontowritedirectlytotheRTSIlinestotriggerotherdevices,asshown.

NI-MotionCReferenceHelp.chm::/flex_set_port.html

High-SpeedCaptureInputUsingRTSIWhentheRTSIlinereceivesthetriggerfromadataorimageacquisitiondevice,thecorrespondinghigh-speedcaptureoccurs,asshown.

TorqueControlTomaintainconstanttorqueorforce,thesensorthatreturnsthefeedbacktothemotioncontrollermustreturnavalueproportionaltothetorqueorforce.Themotioncontrolleroperatestorque-controlandposition-controlsystemsinmuchthesameway.Themaindifferenceisthatthefeedbackinposition-controlsystemsreturnsthecurrentposition,whilethefeedbackintorque-controlsystemsreturnsavoltageproportionaltothecurrentforceortorque.YoucanimplementforcefeedbackonNImotioncontrollersusingeitheranalogfeedbackorbymonitoringforce.

NoteTheNISoftMotionControllerdoesnotsupportanalogfeedback.

AnalogFeedbackInthismode,thetorqueorforcesensorisconnectedtooneoftheanaloginputsontheNImotioncontroller.Thatanalogchannelisusedasthefeedbacksensor.

Tuningthecontrolloopwithaforcesensor,whichisananalogfeedbacksensor,producesthesameresultsaswithapositionfeedbacksensor.Dependingupontheresolutionyouareusing,thesystemmayrequirehighergainstoensureafasterresponse.NImotioncontrollershave12-bitor16-bitanaloginputs,whoserangescanbesetfrom0Vto5V,5Vto+5V,0Vto10V,and10Vto+10V.Whenyouusecountsforenteringthevaluesofposition,velocity,acceleration,anddeceleration,youdonotneedtoenterthecounts/revolutionvaluefortheaxis.Refertothemotioncontrollerusermanualforinformationaboutanaloginputranges.

TorqueControlUsingAnalogFeedbackAlgorithmThefollowingfigureshowsthebasicalgorithmfortorquecontrolusinganalogfeedbackapplicabletobothC/C++andLabVIEWcode.

TorqueControlUsingAnalogFeedbackLabVIEWDiagramThefollowingblockdiagramdemonstratesusingNI-Motiontoperformtorquecontrolusinganalogfeedback.



7ReadperAxisStatus


5LoadTargetPosition

8MotionErrorHandler


6StartMotion

TorqueControlUsingAnalogFeedbackC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)


u8axis;//Axisnumber



u16moveComplete;





///////////////////////////////

//SettheboardID

boardID=1;

//Settheaxisnumber

axis=1;

////////////////////////////////

//-----------------------------------------------------------

//IsisassumedthattheaxisbeingmovedhasanADCchannel

//mappedasitsprimaryfeedback.Positionistreatedasbinary

//volts.Hencevelocityisloadedinbinaryvolts/secand

//accelerationasbinaryvolts/sec^2.

//-----------------------------------------------------------

//Setthevelocityforthemove(inbinaryvolts/sec)


CheckError;

//Settheaccelerationforthemove(inbinaryvolts/sec^2)


CheckError;

//Setthedecelerationforthemove(inbinaryvolts/sec^2)


CheckError;

//Setthejerk-s-curvetime(insampleperiods)


CheckError;

//Settheoperationmode

err=flex_set_op_mode(boardID,axis,NIMC_ABSOLUTE_POSITION);

CheckError;

//LoadPositioncorrespondingtothevoltagewhichyouwant

//themotortomaintain(2047~5Vinthisexample)

err=flex_load_target_pos(boardID,axis,2047,0xFF);

CheckError;

//Startthemove


CheckError;

do

axisStatus=0;


err=flex_check_move_complete_status(boardID,axis,0,&moveComplete);

CheckError;



CheckError;



CheckError;




CheckError;



/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











MonitoringForceYoucanusethissecondforce-feedbackmodeifyouhaveapositionsensoronthemotor,inadditiontothetorquesensor.Thecontrollooponthemotioncontrollerclosesthepositionandvelocityloopsasusual.UseMAXtomaptheencoderasthefeedbackdevicefortheaxis.

Formonitoringforce,createanouterlooptomonitorthetorquesensor,andmovethemotorbasedonthevaluereadfromthetorquesensor.

TorqueControlUsingMonitoringForceAlgorithmThefollowingfigureshowsthebasicalgorithmfortorquecontrolusingmonitoringforceapplicabletobothC/C++andLabVIEWcode.

TorqueControlUsingMonitoringForceLabVIEWDiagramThefollowingblockdiagramdemonstratesusingNI-Motiontoperformtorquecontrolusingmonitoringforce.



7StartMotion


5ReadADC 8ReadperAxisStatus


6LoadTargetPosition

9MotionErrorHandler

TorqueControlUsingMonitoringForceC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)


u8axis;//Axisnumber



i32constant;//Constantforce

i16adcValue;//ADCvalueread





///////////////////////////////

//SettheboardID

boardID=1;

//Settheaxisnumber

axis=1;

//constantforceneededtobemaintained

//correspondsto5Vfora+/-5VADCsettings

constant=2047;

////////////////////////////////

//-----------------------------------------------------------

//Isisassumedthattheaxisbeingmovedhasanencoder

//mappedasitsprimaryfeedback

//-----------------------------------------------------------



CheckError;



CheckError;



CheckError;



CheckError;


err=flex_set_op_mode(boardID,axis,NIMC_RELATIVE_POSITION);

CheckError;

do

//ReadtheADCchannelnumber1andcalculatethepositiontobeupdated

err=flex_read_adc_rtn(boardID,NIMC_ADC1,&adcValue);

CheckError;

if((constant-adcValue)!=0)

err=flex_load_target_pos(boardID,axis,(constant-adcValue),0xFF);

CheckError;

//Movebasedondeltaforce


CheckError;



CheckError;



CheckError;




CheckError;


while(!(axisStatus&NIMC_AXIS_OFF_BIT));//Exitonaxisoff


/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











SpeedControlBasedonAnalogValueInasystemwhereafeedrollmustrunatspeedsbasedonaninputvoltage,thealgorithmtomaintainthespeedconsistsofreadingtheanalogvoltageconnectedtooneoftheanalogchannelsonthemotioncontroller,andupdatingthespeedoftheaxisbasedonthevalueofthevoltageread.Inthissystem,thefeedbackisanormalpositionsensor,suchasanencoder.

SpeedControlBasedonAnalogFeedbackAlgorithmThefollowingfigureshowsthebasicalgorithmforspeedcontrolusingbasedonanalogfeedbackapplicabletobothC/C++andLabVIEWcode.

Theanaloginputcouldbeconnectedtoaforcesensor,whichensuresthatthetensionofawebbeingfedismaintained.

SpeedControlBasedonAnalogFeedbackLabVIEWDiagramThefollowingblockdiagramdemonstratesusingNI-Motiontoperformspeedcontrolbasedonanalogfeedback.


1LoadVelocity 5StartMotion

8StartMotion


6ReadADC 9ReadperAxisStatus


7LoadVelocity


4SetOperationMode

SpeedControlBasedonAnalogFeedbackC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)


u8axis;//Axisnumber



i32constant;//Constantmultiplier

i16adcValue;//ADCvalueread





///////////////////////////////

//SettheboardID

boardID=1;

//Settheaxisnumber

axis=1;

//constanttomultiplytheADCvaluereadtocalculatetherequiredvelocity

constant=10;

////////////////////////////////



CheckError;



CheckError;



CheckError;



CheckError;



CheckError;

//Startthemove


CheckError;

do

//ReadtheADCchannelnumber1andcalculatethevelocitytobeupdated

err=flex_read_adc_rtn(boardID,NIMC_ADC1,&adcValue);

CheckError;

//SetthevelocitybasedontheADCvalueread

err=flex_load_velocity(boardID,axis,(adcValue*constant),0xFF);

CheckError;

//Updatethevelocity


CheckError;



CheckError;



CheckError;




CheckError;


while(!(axisStatus&NIMC_AXIS_OFF_BIT));//Exitonaxisoff


/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











OnboardProgramsThissectionprovidesinformationabouthowonboardprogramsworkfortheNISoftMotionControllerandforNI73xxmotioncontrollers.

UsingOnboardProgramswiththeNISoftMotionControllerTouseonboardprogramswiththeNISoftMotionController,usetheLabVIEWReal-TimeModule(RT)totargetyourapplicationtoruninthesameenvironmentastheNISoftMotionController.BecausetheNISoftMotionControlleronboardprogramsharesthesameprocessorandsystemresourceswiththeNISoftMotionController,ensureyouconsiderthefollowingpointsbeforerunningyourapplicationinLabVIEWRT:

EnsurethatyourtoplevelVIisconfiguredtorunatnormal,abovenormal,orhighpriority.IfyouaretargetingLabVIEWRTforETS,usethetimedloopinsteadofchangingthepriorityofyourtoplevelVI.FollowtheguidelinesintheLabVIEWReal-TimeModuleUserManual.Theguidelinesregardingmemoryallocationandusingsharedresourcesareespeciallyimportant.ThejitterofthesystemincreaseswiththenumberofdevicesusedinyourRTsystem.Enableonlythedevicesyouneedtouseforthecurrentapplication.Becauseinterruptscausejitter,NationalInstrumentsrecommendsyouconfigureyourapplicationtopollfordataperiodicallyratherthanwaitonaninterrupt.YoucanfurtherdecreasethejitterunderETSbyconfiguringtheEthernetmodetobepolling.YouconfigurethesesettingsfortheRTcontrollerinMeasurement&AutomationExplorer(MAX).UnderLabVIEWRT,theNISoftMotionControllerrunsinthebackgroundattimecriticalpriority.TheNISoftMotionControllerisdesignedtoconsumelessthan40%oftheprocessorbandwidth.TherateatwhichtheNISoftMotionControllerupdatesitsdataistypically100Hz.

UsingOnboardProgramswithNI73xxMotionControllersYoucanusethereal-timeoperatingsystemontheNI73xxmotioncontrollertoruncustomprograms.Thisfunctionalityallowsyoutooffloadtasksfromthehostprocessorandontothemotioncontroller.Usingonboardvariables,whichareglobaldataonthedevice,arithmeticandloopoperations,andefficientwaitfunctions,youcanwriteonboardprogramstoexecutepartsofthemotionapplicationwithalmostnohostinteraction.Youcanexecuteupto10onboardprogramssimultaneously.OnboardprogramshavetheleastpriorityinapreemptivemultitaskingenvironmentrunningontheembeddedmicroprocessorbecausetheprimaryfunctionoftheembeddedprocessorissupervisorycontrolandI/Oreaction.Instead,theonboardprogramsruninatime-slicedmanneratthelowestpriority.Eachonboardprogramgetsadefaulttimesliceoftwomilliseconds,afterwhichitrelinquishescontroloftheprocessortothenextonboardprogramorhousekeepingtask.ThehostcommunicationandI/Oreactiontaskstakehigherprioritythantheonboardprogramsandhousekeepingtasks,asshowninthefollowingfigure.Theonboardprogramsandhousekeepingtasksaretime-slicedamongthemselves.Forgreatercontrolanddeterminismforthemotioncontrolsystem,NationalInstrumentsofferstheLabVIEWReal-Time(RT)modulemotioncontrolsystem,whichconsistsofaPXIchassis,PXImotioncontrollerorcontrollers,LabVIEWRT,andNI-Motiondriversoftware.

NoteIfyoucontinuouslypolldatafromthehost,theonboardprogramgetspreemptedandhaslesstimetorun.Tokeepthisfromhappening,insertasmalldelayinthepollingloopsonthehost.RefertoTimingLoopsforinformationaboutprogrammingdelaysintheloops.

WritingOnboardProgramsNoteThissectionappliesonlytoNI73xxmotioncontrollers.

AlmostallNI-Motionfunctionsthatexecuteonthehostcanrunonboard.Thesizeandnumberofprogramsiscompletelyflexible.Itisultimatelylimitedbythe32totalmemoryobjectsintheObjectRegistryorbytotalavailablememory,whicheverisreachedfirst.RefertoBeginProgramStorageVIorfunctionformoreinformation.Theseonboardprogramsremainonthemotioncontrolleruntilyouresetit.Ifyouwanttheonboardprogramstopersistthrougharesetofthemotioncontroller,savethemtoFLASH,asshown.

1Writetheprogramyouwanttoloadontoonboardmemory.

YoucanusemostNI-MotionfunctionsbetweentheBeginProgramStorageVIorfunctionandtheEndProgramStorageVIorfunction.2RuntheprogramtostoretheNI-MotionfunctionsontotheonboardRAM.3StoretheprogramtoFLASHmemoryusingtheObjectMemoryManagementVIorfunctionorMAXformorepermanentstorage(optional).

NI-MotionCReferenceHelp.chm::/flex_begin_store.html

NI-MotionCReferenceHelp.chm::/flex_end_store.html

NI-MotionCReferenceHelp.chm::/flex_object_mem_manage.html

OnboardProgramAlgorithmThefollowingfigureshowsanonboardprogramalgorithmapplicabletobothC/C++andLabVIEWcode.

OnboardProgramLabVIEWDiagramThefollowingblockdiagramdemonstratesusingNI-Motionwithonboardprograms.


1BeginProgramStorage

4LoadAccel/DecelinRPS/s

6StartMotion

2LoadTargetPosition


7EndProgramStorage

3LoadVelocityinRPM

OnboardProgramC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)


u8axis;//Axisnumber






///////////////////////////////

//SettheboardID

boardID=1;

//Settheaxisnumber

axis=1;

////////////////////////////////

//--------------------------------------------------------

//Onboardprogram1.Thisonboardprogrammovesaxisone

//clockwise5000counts(steps).Toexecutethisonboardprogram

//calltheRunProgramfunction

//--------------------------------------------------------

//Beginonboardprogramstorage-programnumber1

err=flex_begin_store(boardID,1);

CheckError;



CheckError;

//LoadTargetPositiontomoveclockwise5000counts(steps)


CheckError;

//LoadVelocityinRPM

err=flex_load_rpm(boardID,axis,100.00,0xFF);

CheckError;

//LoadAccelerationandDecelerationinRPS/sec

err=flex_load_rpsps(boardID,axis,NIMC_BOTH,50.00,0xFF);

CheckError;

//Startthemove


CheckError;

//Waitformovetocomplete

err=flex_wait_on_condition(boardID,0,NIMC_WAIT,NIMC_CONDITION_MOVE_COMPLETE,2/*Indicatesaxis1*/,

0,NIMC_MATCH_ALL,1000/*timeout*/,0);

CheckError;

//EndProgramStorage

err=flex_end_store(boardID,1);

CheckError;


/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











Running,Stopping,andPausingOnboardPrograms

NoteThissectionappliesonlytoNI73xxmotioncontrollers.

UseRunProgram,StopProgram,andPause/ResumeProgramtorun,stop,andpauseanonboardprogramthatresidesintheonboardmemoryofamotioncontroller.

NoteRecursivelycallinganonboardprogramgeneratesanerror.

RunninganOnboardProgramTheRunProgramVIorfunctionexecutespreviouslystoredprogramsfromRAMorFLASH.Typically,youmustcallRunProgramfromthehost,becauseitisnotpossibleforanonboardprogramtorunitself.However,itispossibletoconfigurethemotioncontrollertoautomaticallyrunanonboardprogramuponpoweringupthemotioncontrolsystem.YoualsocancallanonboardprogramfromanotheronboardprogramusingRunProgram.

NI-MotionCReferenceHelp.chm::/flex_run_prog.html

StoppinganOnboardProgramTheStopProgramVIorfunctionendstheexecutionofanonboardprogramthatiscurrentlyrunning.StoppinganonboardprogramusingStopProgramcompletelyendsexecution.Itisnotpossibletoresumeexecutionofthestoppedonboardprogram,butyoucanre-runtheprogramfromthebeginning.YoucanstopanonboardprogramwithaStopProgramVIorfunctioncallfromthehostorfromanotheronboardprogram.

NoteItisnotpossibleforanonboardprogramtostopitself.

TipStoppinganonboardprogramisdifferentfromstoppingthemotionoftheaxisoraxes.Whenyoustopanonboardprogram,anymovesthathavestartedcontinuetorun.YoumustseparatelycalltheStopMotionVIorfunctiontostopthemotionoftheaxisoraxes.

NI-MotionCReferenceHelp.chm::/flex_stop_prog.html


Pausing/ResuminganOnboardProgramThePause/ResumeProgramVIorfunctionsuspendsexecutionofarunningonboardprogram,orresumesexecutionofapreviouslypausedonboardprogram.Youcanpauseanonboardprogramwithafunctioncallfromthehost,fromtheonboardprogramitself,orfromanotherrunningonboardprogram.Youcanresumeanonboardprogramwithafunctioncallfromthehostorfromanotherrunningonboardprogram.

NoteItisnotpossibleforanonboardprogramtoresumeitself.

TipSimilartotheStopProgramVIorfunction,Pause/ResumeProgramhasnoeffectonmovesthathavestarted.

AutomaticPausingAnyrun-timeerrorthatoccursduringexecutionautomaticallypausestheonboardprogram.AnonboardprogramalsopausesautomaticallywhenitexecutestheStartMotionVIorfunctionortheBlendMotionVIorfunctiononanaxisthathasbeenstoppedbythehost,orwhenanaxisisstoppedduetoalimit,home,softwarelimit,orfollowingerrorcondition.Single-SteppingUsingPauseYoucanusethePause/ResumeProgramVIorfunctiontoeffectivelysingle-stepthroughanonboardprogram.Tosingle-step,addaPause/ResumeProgramcallaftereachfunction,andthenresumetheonboardprogramfromthehost.

NI-MotionCReferenceHelp.chm::/flex_pause_prog.html

NI-MotionCReferenceHelp.chm::/flex_stop_prog.html

NI-MotionCReferenceHelp.chm::/flex_start.html

NI-MotionCReferenceHelp.chm::/flex_blend.html

ConditionallyExecutingOnboardProgramsNoteThissectionappliesonlytoNI73xxmotioncontrollers.

Youcansetconditionsthataffecttheexecutionoftheonboardprograms.Forexample,youmaywanttheonboardprogramtowaituntilaspecificeventoccurs,andthencontinueexecuting.TheWaitonConditionVIortheWaitonEventfunctionallowsyoutocreateonboardprogramsthatwaitforevents,suchasmovecompleteandblendcomplete.Theseonboardprogramscansendfunctionstostartmovesandwaitformovestocomplete.Theonboardprogramusesalmostnoprocessortimewhilewaitingforaneventsuchasmovecomplete.Whenthemoveiscomplete,thetrajectorygeneratorenablestheI/Oreactiontask,whichcausestheonboardprogramtocontinueexecutingthenextfunctioninitssequence,asshowninthefollowingfigure.

NI-MotionCReferenceHelp.chm::/flex_wait_on_event.html

OnboardProgramConditionalExecutionAlgorithmThefollowingfigureshowsthebasicalgorithmforconditionallyexecutinganonboardprogramapplicabletobothC/C++andLabVIEWcode.

OnboardProgramConditionalExecutionLabVIEWDiagramThefollowingblockdiagramdemonstratesusingNI-Motiontoconditionallyexecuteanonboardprogram.



4LoadTargetPosition

7StartMotion

2SetOperationMode 5SelectMOMO 8EndProgramStorage

3LoadVelocityinRPM

6WaitonCondition 9MotionErrorHandler

OnboardProgramConditionalExecutionC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)


u8axis;//Axisnumber






///////////////////////////////

//SettheboardID

boardID=1;

//Settheaxisnumber

axis=1;

////////////////////////////////



CheckError;

//LoadVelocityinRPM


CheckError;



CheckError;



CheckError;

//LoadTargetPositiontomoverelative5000counts(steps)


CheckError;

//Waitforline1onport1togoactivetofinishexecuting

err=flex_wait_on_condition(boardID,NIMC_IO_PORT1,NIMC_WAIT,NIMC_CONDITION_IO_PORT_MATCH,(u8)(1<<1)/*Indicatesline1*/,


CheckError;

//Startthemove


CheckError;


err=flex_wait_on_condition(boardID,0,NIMC_WAIT,NIMC_CONDITION_MOVE_COMPLETE,(u8)(1<<axis),


CheckError;

//EndProgramStorage


CheckError;


/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











UsingOnboardMemoryandDataNoteThissectionappliesonlytoNI73xxmotioncontrollers.

NImotioncontrollersallowyoutoaccesstheonboardRAMandFLASHtocreatedatabuffersandusesomegeneral-purposeonboardvariablesfordatamanipulation.Youcanusethismemorytoupdatedatathatisloadedbyfunctionsthatareexecutinginanonboardprogram.Youalsocansynchronizeexecutionordatabetweenthehostcomputerandthemotioncontroller.Forexample,youmaywanttoupdatethevelocityofanaxisbasedontheanalogvoltagereadfromanADCchannel.Thismemoryisstaticallyallocated.

UpdatingVelocityBasedonADCChannelAlgorithmThefollowingfigureshowsthebasicalgorithmforupdatingvelocitybasedonanADCchannelusinganonboardprogramapplicabletobothC/C++andLabVIEWcode.

Beforeyouexecutethisprogram,settheoperationmodeoftheaxistovelocitymode.

UpdatingVelocityBasedonADCChannelLabVIEWDiagramThefollowingblockdiagramdemonstratesusingNI-MotiontoupdatevelocitybasedonanADCchannel.


1LoadConstanttoVariable

6ReadADC 11StartMotion


7MultiplyVariables 12ReadVariable


8SubtractVariables 13JumptoLabelonCondition

4SetOperationMode

9JumptoLabelonCondition

14EndProgramStorage

5InsertProgramLabel

10LoadVelocity 15MotionErrorHandler

UpdatingVelocityBasedonADCChannelC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)


u8axis;//Axisnumber


i32constant;//Constantmultiplier





///////////////////////////////

//SettheboardID

boardID=1;

//Settheaxisnumber

axis=1;

//constanttomultiplytheADCvaluereadtocalculatetherequiredvelocity

constant=10;

////////////////////////////////

//Initializeonboardvariable4to0

err=flex_load_var(boardID,0,4);

CheckError;

//Initializeonboardvariable1totheconstantmultiplier

err=flex_load_var(boardID,constant,1);

CheckError;





CheckError;

//InsertLabelnumber1

err=flex_insert_program_label(boardID,1);

CheckError;

//ReadADCchannelandstoreADCvalueinvariable2

err=flex_read_adc(boardID,NIMC_ADC1,2);

CheckError;

//MultiplyVariables2i.e.theADCvaluewith1i.e.theconstant

//Savetheresultinvariable3

err=flex_mult_vars(boardID,1,2,3);

CheckError;

//Subtractvalueinvariable3fromvariable4

//Wearenotinterestedintheresult-justwantto

//settheconditiononboard.

err=flex_sub_vars(boardID,3,4,0);

CheckError;

//Jumptolabel1asthesubtractionabovesetthecondition

//to"equaltozero"whichimpliesthatthevaluesinvariable

//3and4arethesame

err=flex_jump_label_on_condition(boardID,0,NIMC_CONDITION_EQUAL,0,0,NIMC_MATCH_ALL,1/*labelnumber*/);

//Setthevelocityforthemove(incounts/sec)byloadingthe

//valuefromvariable3whichis(adcvalue*constant)

err=flex_load_velocity(boardID,axis,0,3);

CheckError;

//Startthemovetoupdatethevelocity


CheckError;

//Savethevalueinvariable3tovariable4foruse

//innextcycle

err=flex_read_var(boardID,3,4);

CheckError;

//Jumpbacktolabel1unconditionally

err=flex_jump_label_on_condition(boardID,0,NIMC_CONDITION_TRUE,0,0,NIMC_MATCH_ALL,1/*labelnumber*/);

CheckError;

//EndProgramStorage


//ToexecutethisprogramusetheRunProgramfunction


/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











BranchingOnboardProgramsNoteThissectionappliesonlytoNI73xxmotioncontrollers.

Tocreateloops,orconditionalifstatements,insertlabelsintheprogramyouarestoringandusetheJumptoLabelonConditionVIortheJumponEventfunctiontojumptothatlabelbasedonthecondition.

NI-MotionCReferenceHelp.chm::/flex_jump_on_event.html

BranchingOnboardProgramsAlgorithmThefollowingfigureshowsanonboardprogramwaitingforanI/OlinetogoactivebeforestartingamoveapplicabletobothC/C++andLabVIEWcode.

BranchingOnboardProgramsLabVIEWDiagramThefollowingblockdiagramdemonstratesusingNI-Motiontoaddconditionaljumpsinanonboardprogram.



6SelectMOMO 10WaitonCondition

2SetOperationMode

7WaitonCondition


3LoadVelocityinRPM

8StartMotion 12EndProgramStorage

4InsertProgramLabel

9SelectMOMO 13MotionErrorHandler

5LoadTargetPosition

BranchingOnboardProgramsC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)


u8axis;//Axisnumber






///////////////////////////////

//SettheboardID

boardID=1;

//Settheaxisnumber

axis=1;

////////////////////////////////



CheckError;

//LoadVelocityinRPM


CheckError;



CheckError;



CheckError;



CheckError;

//LoadTargetPositiontomoverelative5000counts(steps)


CheckError;

//Waitforline1onport1togoactivetofinishexecuting

err=flex_wait_on_condition(boardID,NIMC_IO_PORT1,NIMC_WAIT,NIMC_CONDITION_IO_PORT_MATCH,(u8)(1<<1)/*Indicatesline1*/,


CheckError;

//Startthemove


CheckError;


err=flex_wait_on_condition(boardID,0,NIMC_WAIT,NIMC_CONDITION_MOVE_COMPLETE,(u8)(1<<axis),


CheckError;

//Jumpunconditionallytolabel1andcheckIOlineagain


CheckError;

//EndProgramStorage


CheckError;


/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











MathOperationsNoteThissectionappliesonlytoNI73xxmotioncontrollers.

NI-Motionalwaysperformsmathoperationsonvaluesstoredinonboardvariables,andallmathoperationssetaglobalconditionthattheJumptoLabelonConditionVIortheJumponEventfunctionusestodetermineiftheoperationjumpstoaparticularlabelintheonboardprogram.Toloadtheonboardvariables,usetheLoadConstanttoVariableVIorfunctionorpointthereturnvectorintheReadfunctionstotheonboardvariablewhereyouwantthedatatobesaved.Inthepreviousexample,theADCchannelisreadtoonboardvariable2.Thisvalueisthenmultipliedwithascalefactorloadedintovariable1usingtheLoadConstanttoVariableVIorfunction.YoucanperformAdd,Multiply,Subtract,Divide,AND,OR,XOR,NOT,andlogicalshiftmathoperations.Theconditioncodealwaysreflectsthelastmathoperationperformed.LessThanimplieslessthanzero,Equalimpliesequaltozero,andsoon.

NI-MotionCReferenceHelp.chm::/flex_jump_on_event.html

NI-MotionCReferenceHelp.chm::/flex_load_var.html

NI-MotionCReferenceHelp.chm::/flex_load_var.html

IndirectVariablesNoteThissectionappliesonlytoNI73xxmotioncontrollers.

Ifyoumakethereadorloadfunctionspointtovariables0x81to0xF8,thefunctionsusethevalueloadedinvariables1to0x78andinterpretthemastheaddresswherethevalueisreadorloaded.Thiscreatestwolevelsofindirection.MakingthereturnvectoroftheReadPositionVIorfunctionpointto0x81causesthepositiontoendupintheaddresscontainedinonboardvariable1,asshown.

Usingindirectvariablescanbeveryusefulinloopinginonboardprograms,aswellasdynamicallychangingtheinputvaluestofunctions.

NI-MotionCReferenceHelp.chm::/flex_read_pos.html

OnboardBuffersNoteThissectionappliesonlytoNI73xxmotioncontrollers.

YoucanusethememoryontheNImotioncontrollerstocreategeneral-purposebufferstoreadandwritedata,asshowninthefollowingfigure.

Buffersarecreatedfromadynamicpoolofmemory,soyoumustfreethememorywhenthebufferisnotrequired.ThissamepoolofmemoryisusedtostoreonboardprogramsinRAM.Asthenumberorsizeofbuffersincreases,theavailablememoryforstoringonboardprogramsdecreases.

OnboardBuffersAlgorithmThefollowingfigureshowsthealgorithmforusingonboardbufferstostoredataapplicabletobothC/C++andLabVIEWcode.

SynchronizingHostApplicationswithOnboardPrograms

NoteThissectionappliesonlytoNI73xxmotioncontrollers.

Thehostandtheonboardprogramcanwritetothemovecompletestatus(MCS)registerusingtheSetUserStatusMOMOVIorfunction.ThisVIorfunctioncontrolstheupperthreebitsintheMCSregisterusingtheMustOn/MustOff(MOMO)protocol.Usethesebitstosynchronizeanapplicationrunningonthehostcomputerwithanonboardprogram,asshowninthefollowingfigure.

Forexample,considerahostapplicationthatreadsanonboardvariablethathasbeenupdatedbyanonboardprogram.Usethefollowingalgorithmtosynchronizethehostapplicationwithanonboardprogram,andreadanonboardvariablethathasbeenupdatedbyanonboardprogram.

NI-MotionCReferenceHelp.chm::/flex_set_status_momo.html

SynchronizingHostApplicationswithOnboardProgramsAlgorithmThefollowingfigureshowsanalgorithmforusinganonboardprogramtosynchronizehostapplicationsapplicabletobothC/C++andLabVIEWcode.

SynchronizingHostApplicationswithOnboardProgramsLabVIEWDiagram


Thisexamplemovesaxis1betweentargetpositionsof5000and5000.Thehostreadsthetargetpositiononlyafterthemovehascompleted,andthenewtargetpositionhasbeencalculated.Thefollowingfigureshowsthecodethatrunsasanonboardprogram.


6InsertProgramLabel

11MultiplyVariables


7LoadTargetPosition

12SetUserStatusMOMO


8StartMotion 13JumptoLabelonCondition

4SetOperationMode 9SelectMOMO 14EndProgramStorage

5LoadVelocity 10WaitonCondition


Thefollowingfigureshowsthecodethatrunsonthehost.

1ReadMoveCompleteStatus

2SetUserStatusMOMO

3ReadVariable

NoteAsthehostispollingaregisteronthemotioncontroller,itisnotinvokingtheHostCommunicationTaskonthereal-timeoperatingsystemonthemotioncontroller.Therefore,theonboardprogramsexecutingarenotpreempted.Inthissituation,theonboardprogramsrundeterministically.

SynchronizingHostApplicationswithOnboardProgramsC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)


u8axis;//Axisnumber


i32targetPosition;//Movelength

i32multiplier;//multiplier


u16moveCompleteStatus;//Movecompletestatus





///////////////////////////////

//SettheboardID

boardID=1;

//Settheaxisnumber

axis=1;

//Setthemovelength

targetPosition=5000;

//Setthemultiplier

multiplier=-1;

////////////////////////////////

//--------------------------------------------------------

//Onboardprogram.Thisonboardmovesanaxisbackand

//forthbetweentargetPositionand-targetPosition.Before

//reversingdirectionsitindicatestothehostcomputerthat

//itisabouttodoso.

//--------------------------------------------------------

//Initializeonboardvariable2tothemultiplierusedtochangethe

//targetposition

err=flex_load_var(boardID,multiplier,2);

CheckError;

//Initializeonboardvariable1tothetargetposition

err=flex_load_var(boardID,targetPosition,1);

CheckError;




err=flex_set_op_mode(boardID,axis,NIMC_ABSOLUTE_POSITION);

CheckError;

//Setthevelocity


CheckError;



CheckError;

//LoadTargetPositionfromonboardvariable1

err=flex_load_target_pos(boardID,axis,0,1);

CheckError;

//Startthemove


CheckError;


err=flex_wait_on_condition(boardID,0,NIMC_WAIT,NIMC_CONDITION_MOVE_COMPLETE,(u8)(1<<axis)/*Indicatesaxistowaiton*/,


CheckError;

//MultiplyVariables1i.e.thetargetpositionwith2i.e.themultiplier

//Savetheresultinvariable1-thiscalculatesthenegativeoflasttargetposition

err=flex_mult_vars(boardID,1,2,1);

CheckError;

//Setthe13thbitinthemovecompletestatusregistersothatthehost

//knowsthattheaxisisabouttoreversedirection

err=flex_set_status_momo(boardID,0x20,0);

CheckError;

//Jumpunconditionallytoloadnewtargetposition


CheckError;

//EndProgramStorage


CheckError;

//--------------------------------------------------------

//Hostprogram.Thisprogramsmonitorsthe13thbitinthe

//movecompletestatusregisterandrecordstheposition

//theaxisisgoingtomoveto

//--------------------------------------------------------

do



CheckError;



CheckError;




CheckError;

//Readthemovecompletestatusregisterandoncethe13thbitisset

//resetthebitandreadsthetargetposition

err=flex_read_mcs_rtn(boardID,&moveCompleteStatus);

CheckError;

if(moveCompleteStatus&(1<<13))

i32currentTargetPosition;

//Resetthe13thbitinthemovecompletestatusregister

err=flex_set_status_momo(boardID,0,0x20);

CheckError;

err=flex_read_var_rtn(boardID,1,&currentTargetPosition);

CheckError;


while(!(axisStatus&NIMC_FOLLOWING_ERROR_BIT)&&!(axisStatus&NIMC_AXIS_OFF_BIT));//


/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











OnboardSubroutinesNoteThissectionappliesonlytoNI73xxmotioncontrollers.

Youcancreatesubroutinestorunasonboardprogramsandexecutethemfromwithinanonboardprogram.

OnboardSubroutineAlgorithmThefollowingfigureshowsanonboardprogramalgorithmthatcheckstheI/OlinestatetodeterminewhichonboardsubroutinetoexecuteapplicabletobothC/C++andLabVIEWcode.

IftheI/Olineisactive,themainonboardprogramcallsanonboardsubroutinethatrotatesthemotorclockwise.IftheI/Olineisinactive,themainonboardprogramcallsanonboardsubroutinethatrotatesthemotorcounterclockwise.

OnboardSubroutineLabVIEWDiagramTipRefertoNI-Motion\Documentation\Examples\NI-MotionUserManual\fortheLabVIEWVIsfortheseexamples.

Thefollowingfigureshowsthemainonboardprogramusedtodeterminethesubroutinecall.


6WaitonCondition 10WaitonCondition

2InsertProgramLabel



3SelectMOMO 8InsertProgramLabel

12EndProgramStorage


9RunProgram 13MotionErrorHandler

5RunProgram

Thefollowingfigureshowsthesubroutinethatcausesthemotortorotateclockwise.


5LoadAccel/DecelinRPS/sec

8WaitonCondition

2SetOperationMode


3LoadTargetPosition


4LoadVelocityinRPM

Thefollowingfigureshowsthesubroutinethatcausesthemotortorotatecounterclockwise.


5LoadAccel/DecelinRPS/sec

8WaitonCondition

2SetOperationMode


3LoadTargetPosition


4LoadVelocityinRPM

OnboardSubroutineC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)


u8axis;//Axisnumber






///////////////////////////////

//SettheboardID

boardID=1;

//Settheaxisnumber

axis=1;

////////////////////////////////

//--------------------------------------------------------


//clockwise5000counts(steps).Thisonboardprogram

//isexecutedbyonboardprogramone.

//--------------------------------------------------------



CheckError;



CheckError;

//LoadTargetPositiontomoveclockwise5000counts(steps)


CheckError;

//LoadVelocityinRPM


CheckError;



CheckError;

//Startthemove


CheckError;




CheckError;

//EndProgramStorage


CheckError;

//--------------------------------------------------------


//counterclockwise5000counts(steps).Thisonboardprogram

//isexecutedbyonboardprogramone.

//--------------------------------------------------------



CheckError;



CheckError;

//LoadTargetPositiontomovecounterclockwise5000counts(steps)

err=flex_load_target_pos(boardID,axis,-5000,0xFF);

CheckError;

//LoadVelocityinRPM


CheckError;



CheckError;

//Startthemove


CheckError;




CheckError;

//EndProgramStorage


CheckError;

//--------------------------------------------------------

//Onboardprogram1.Themainonboardprogrammonitors

//anIOlineandbasedonstateoftheIOlineexecutes

//onboardprogram2oronboardprogram3

//--------------------------------------------------------



CheckError;



CheckError;

//Jumptolabel2iftheline1onportoneisactive

err=flex_jump_label_on_condition(boardID,NIMC_IO_PORT1,NIMC_CONDITION_IO_PORT_MATCH,2/*Indicatesline1*/,0,NIMC_MATCH_ALL,2/*labelnumber*/);

CheckError;

//Iftheabovejumpfailedi.e.theIOlineisnotactive

//executeprogram#3

err=flex_run_prog(boardID,3);

CheckError;

//Waitforprogram#3tofinishexecuting

err=flex_wait_on_condition(boardID,3/*program#*/,NIMC_WAIT,NIMC_CONDITION_PROGRAM_COMPLETE,0,0,NIMC_MATCH_ALL,1000/*timeout*/,0);

CheckError;



CheckError;



CheckError;

//Executeprogram#2

err=flex_run_prog(boardID,2);

CheckError;

//Waitforprogram#2tofinishexecuting

err=flex_wait_on_condition(boardID,2/*program#*/,NIMC_WAIT,NIMC_CONDITION_PROGRAM_COMPLETE,0,


CheckError;



CheckError;

//

//

//EndProgramStorage


CheckError;


/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











AutomaticallyStartingOnboardProgramsNoteThissectionappliesonlytoNI73xxmotioncontrollers.

YoucanconfiguretheonboardprogramtostartautomaticallywithoutcallingtheRunProgramVIorfunction.Theonboardprogramrunsassoonasthemotioncontrollerexitstheresetstate.Tousethisfeature,savetheonboardprogramtoFLASH,andthencalltheEnableAutoStartVIorfunction.Themotioncontrollercheckstoseeiftheauto-startflagissetwhenitbootsup.Iftheflagisset,themotioncontrollerexecutestheonboardprogramconfiguredtoautomaticallystart.Theauto-startrequiresnohostinteractionafteritissetup.Automaticallystartingtheonboardprogramsisveryusefulifyouneedtoexecutemonitoringtaskstobeginassoonasthecomputerandcontrollerbootup.

NI-MotionCReferenceHelp.chm::/flex_run_prog.html

NI-MotionCReferenceHelp.chm::/flex_enable_auto_start.html

ChangingaTimeSliceNoteThissectionappliesonlytoNI73xxmotioncontrollers.

UsetheLoadProgramTimeSliceVIorfunctiontospecifytheminimumtimeanonboardprogramhastoberunperwatchdogperiod,withatotalof20msallowedforallrunningonboardprograms.Thedefaultvalueof2msallowsamaximumof10onboardprogramsrunningsimultaneouslywithequaltimeslices.Youcanincreasethetimesliceoftheprogramtochangeitsperformance.Thehigheryousetthetimeslice,themoretheprogramcanexecute,becauseitcommandsmoreprocessortime.However,becausetheprocessingpowerisbeingheldlongerbytheonboardprogram,theresponsetimesofotheronboardprogramsareslower.Also,increasingthetimesliceofaprogrammayreducehostresponsivenessandincreaseI/Oreactiontime,eventhoughhostcommunicationsandI/Oreactionhavehigherprioritiesthanonboardprogramsbecausethemotioncontrollermustguaranteethateveryprogramrunsforitsallottedtimeperwatchdogperiod.

NI-MotionCReferenceHelp.chm::/flex_load_program_time_slice.html

CreatingApplicationsUsingNI-MotionYoucancombinethemoves,input/output,andotherfunctionalitydiscussedinProgrammingwithNI-Motion,tocreatecompletemotioncontrolapplications.ThefollowingsectionsshowexamplesoftypicalmotioncontrolapplicationsandhowtheyareimplementedusingNI-Motion.

ScanningRotatingKnife

ScanningThegoalofthescanningapplicationistoinspectawaferunderafixedlaser.Multipledetectorscollectthescatteredlaserlightandfeedthedatatoananalysissystemthatmapsanydefects.ThewaferrestsonanXYstagethatmovesintwodimensions.Theobjectiveofthescanistocoverasmuchspaceonthewaferaspossibleintheshortestamountoftime.Scanningagreaterareaincreasesthechancesofdetectingalldefects.Shorteningthescantimelowersthecycletime,andincreasesthespeedoftheproductionortesting.Youcanperformascanningapplicationinoneofthefollowingthreeways:

Movethestageinarasterbyconnectingseveralstraight-linemovesegments.Useblendingtoperformthescaninasinglecontinuousmove.Usecontouringtocreateacustomscanningpathforthestage.

ConnectingStraight-LineMoveSegmentsYoucancovertheentireareaofthewaferbyvaryingthesizeoftherasterarea.Youcanincreasetheresolutionofthescanningpathbyshorteningthedistanceoftheverticalstraight-linemoves.However,rememberthatincreasingtheresolutionalsoincreasesthecycletime.

RasterScanningUsingStraightLinesAlgorithmThefollowingfigureshowsthebasicalgorithmforrasterscanningforstraight-linemovesapplicabletobothC/C++andLabVIEWcode.

Therasterscanningalgorithmforstraight-linemovesstopsthemotorsaftereverysegmentofthemove,sothecycletimeislongerthanothermethods.

RasterScanningUsingStraightLinesLabVIEWDiagramThefollowingblockdiagramdemonstratesusingNI-Motiontoperformrasterscanningusingstraightlines.



5LoadS-CurveTime



10ReadperAxisStatus



11ReadperAxisStatus



RasterScanningUsingStraightLinesC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)





u16status;

u16moveComplete;

u32i;

i32xPosition[11]=5000,5000,0,0,5000,5000,0,0,5000,5000,0;

i32yPosition[11]=0,1000,1000,2000,2000,3000,3000,4000,4000,5000,5000;





///////////////////////////////

//SettheboardID

boardID=1;

//Settheaxisnumber


////////////////////////////////



CheckError;



CheckError;



CheckError;



CheckError;

//Setthejerkors-curveinsampleperiods


CheckError;



CheckError;

//Loadthestraightlinesegmentsonebyone

for(i=0;i<11;i++)

//LoadTargetPosition

err=flex_load_vs_pos(boardID,vectorSpace,xPosition[i],yPosition[i],0,0xFF);

CheckError;

//Startthemove


CheckError;

do

axisStatus=0;



CheckError;



CheckError;

axisStatus|=status;



CheckError;

axisStatus|=status;



CheckError;




CheckError;






/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











BlendingStraight-LineMoveSegmentsBlendingthestraight-linemovesegmentsenablescontinuousmotion,whichdecreasesthecycletimeofthescan.Thecycletimeismuchfasterbecausethemotorsarenotforcedtostopaftereachmovesegment.Thefollowingfigureshowsthepathoftheblendedmovesegments.

RefertoBlendingforinformationaboutusingblendingwithNI-Motion.

RasterScanningUsingBlendedStraightLinesAlgorithmThefollowingfigureshowsthebasicalgorithmforrasterscanningusingblendedstraight-linemovesapplicabletobothC/C++andLabVIEWcode.

RasterScanningUsingBlendedStraightLinesLabVIEWDiagramThefollowingblockdiagramdemonstratesusingNI-Motiontoperformrasterscanningusingblendedstraight-linemoves.



6LoadBlendFactor



11ReadperAxisStatus



12ReadperAxisStatus



5LoadS-CurveTime

RasterScanningUsingBlendedStraightLinesC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)





u16status;

u16complete;//Moveorblendcompletestatus

u32i;

i32xPosition[11]=5000,5000,0,0,5000,5000,0,0,5000,5000,0;

i32yPosition[11]=0,1000,1000,2000,2000,3000,3000,4000,4000,5000,5000;





///////////////////////////////

//SettheboardID

boardID=1;

//Settheaxisnumber


////////////////////////////////



CheckError;



CheckError;



CheckError;



CheckError;

//Setthejerkors-curveinsampleperiods


CheckError;



CheckError;

//Loadthestraightlinesegmentsonebyone

for(i=0;i<11;i++)

//LoadTargetPosition

err=flex_load_vs_pos(boardID,vectorSpace,xPosition[i],yPosition[i],0,0xFF);

CheckError;

if(i==0)

//Startthemove


CheckError;

else

//Blendthemove

err=flex_blend(boardID,vectorSpace,0);

CheckError;

do

axisStatus=0;

if(i==10)


err=flex_check_move_complete_status(boardID,vectorSpace,0,&complete);

CheckError;

else

//Checktheblendcompletestatus

err=flex_check_blend_complete_status(boardID,vectorSpace,0,&complete);

CheckError;



CheckError;

axisStatus|=status;



CheckError;

axisStatus|=status;



CheckError;




CheckError;






/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











User-DefinedScanningPathYoucancreateacustompaththatcoversthemaximumscanareaintheshortesttimeusingthecontouredmovefeatureoftheNImotioncontroller.Thiswayyoubypassthetrajectorygeneratorandsendexactpositionstothemotioncontroller.Thecontrollertheninterpolatesthedistancebetweenthegivenpointsusingacubicsplinealgorithm.Thefollowingfigureshowsthescanningpathusedintheexamples.

Usingthecontouredmovegivesyouthegreatestamountofflexibilityregardingthescanareaandspeed.HoweveryoulosethebenefitofthetrajectorygeneratoroftheNImotioncontroller.RefertoContouredMovesforinformationaboutusingcontouredmoveswithNI-Motion.

User-DefinedScanningPathAlgorithmThefollowingfigureshowsthebasicalgorithmforrasterscanningusingauser-definedpathapplicabletobothC/C++andLabVIEWcode.

User-DefinedScanningPathLabVIEWDiagramThefollowingblockdiagramdemonstratesusingNI-Motiontoperformscanningusingacontouredmove.


1ConfigureVectorSpace 5StartMotion 8ClearBuffer2SetOperationMode 6CheckBuffer 9SetOperationMode3ConfigureBuffer 7WriteBuffer 10MotionErrorHandler4WriteBuffer

User-DefinedScanningPathC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)





u16status;//Temporarycopyofstatus

u16moveComplete;//Movecompletestatus

i32i;

i32points[1994]=NIMC_SPIRAL_ARRAY;//Arrayof2Dpointstomove

u32numPoints=1994;//Totalnumberofpointstocontourthrough



i32*downloadData=NULL;//Thetemporaryarraythatiscreatedtodownloadthepointstothecontroller

u32currentDataPoint=0;//Indicatesthenextpointinthepointsarraythatistobedownloaded

i32backlog;//Indicatestheavailablespacetodownloadmorepoints



u32dataCopied=0;//Keepstackofthepointscopied





///////////////////////////////

//SettheboardID

boardID=1;

//Settheaxisnumber


////////////////////////////////



CheckError;


err=flex_set_op_mode(boardID,vectorSpace,NIMC_ABSOLUTE_CONTOURING);

CheckError;



err=flex_configure_buffer(boardID,1/*buffernumber*/,vectorSpace,NIMC_POSITION_DATA,bufferSize,

numPoints,NIMC_TRUE,10,&actualInterval);

//Sendthefirst1000pointsofthedata

downloadData=malloc(sizeof(i32)*bufferSize);

for(i=0;i<bufferSize;i++)

downloadData[i]=points[i];

currentDataPoint++;

err=flex_write_buffer(boardID,1/*buffernumber*/,bufferSize,0,downloadData,0xFF);

free(downloadData);

downloadData=NULL;

CheckError;

//StartMotion


CheckError;

for(;;)

axisStatus=0;

//Checkforavailablespaceanddownloadremainingpointsevery50milliseconds

Sleep(50);

//Checktoseeifwehavemorepointstodownload

if(currentDataPoint<numPoints)


CheckError;

if(backlog>=300)

downloadData=malloc(sizeof(i32)*backlog);

dataCopied=0;


if(currentDataPoint>numPoints)break;

downloadData[i]=points[currentDataPoint];

currentDataPoint++;

dataCopied++;

err=flex_write_buffer(boardID,1/*buffernumber*/,dataCopied,0,downloadData,0xFF);

free(downloadData);

downloadData=NULL;

CheckError;



CheckError;

if(moveComplete)break;




CheckError;




CheckError;

//Checkthemotoroffstatusonalltheaxesoraxis


CheckError;

axisStatus|=status;


CheckError;

axisStatus|=status;



//Setthemodebacktoabsolutemodetogetthecontrolleroutofcontouring

//mode


CheckError;



CheckError;


/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do











RotatingKnifeThepurposeofthisapplicationistocutawebwitharotatingknife.Theblademustcutpreciselybetweenlabelsontheweb.Becausethewebmaterialcanstretchundercertainconditions,itisnotenoughtocutthewebatconstantlength,becausethelengthofeachlabelcanvary.Toaccomplishthistask,thewebismarkedonetimepercycleattherequiredcuttinglocation.Themotioncontrollerreadsthismarkusingasensorandperformsthenecessarycorrection.Tosimplifythisexample,assumethatthelengthofthecutisequaltothecircumferenceoftheknife.Underidealconditions,themarkshouldbereadwhenthebladeisatpositionA,asshowninthefigurebelow.Therefore,themotorshouldmoveonerevolutionwithoutanycorrectionbeforecausingthecut.

TipRefertoElectronicGearingandCammingforinformationaboutsuperimposedmoves/registrationapplications.

SolutionTherotaryknifeiselectronicallygearedtothewebwithagearratioof1:1,whichensuresthatatthetimeofcut,thespeedofthewebandtheknifeisthesame.Thespeedofeachmustbethesametomakeacleancutwithoutstretchingtheweb.Also,underidealconditions,thewebandrotatingknifemovetheexactsamedistance.Forexample,thelengthofthecutmightbeonerevolution,whichisequalto2,000counts.Thesensorreadingthemarkisconnectedtooneofthehigh-speedcapturelinesonthemotioncontroller.Becausetheelasticityofthewebmaterialresultsinvaryinglabellengths,themarkcanbereadbeforethebladeisatpositionAorafteritisatpositionA.Theapplicationmustcorrectthepositionwherethebladeoftherotaryknifeshouldbewhenthehigh-speedcaptureoccurs.ThiscorrectionmustoccurafterthebladehascrossedpositionAsothatthecurrentcutisnotdamaged.Toaccomplishthisgoal,markthecorrectionpointtobeatpositionB,asshowninthefollowingfigure.

ASynchronizationPoint BCorrectionPoint

RotatingKnifeAlgorithmThefollowingfigureshowsthebasicalgorithmfortherotatingknifeapplicationapplicabletobothC/C++andLabVIEWcode.

RotatingKnifeLabVIEWDiagramThefollowingblockdiagramsdemonstrateusingNI-Motiontoprogramtherotatingknifeapplication.


1ConfigureGearMaster


7EnableHigh-SpeedCapture

2LoadGearRatio 5SetOperationMode

8ReadHigh-SpeedCaptureStatus

3LoadVelocityinRPM

6EnableGearingSingleAxis

9MotionErrorHandler

Thefollowingfiguresshowtheremainingcasesfortheblockdiagramabove.

1ReadCapturedPosition 2LoadTargetPosition

1ReadPosition 2StartMotion

RotatingKnifeC/C++CodeThefollowingexamplecodeisnotnecessarilycomplete,andmaynotcompileifcopiedexactly.RefertotheexamplesfolderontheNI-MotionCDforfilesthatarecompleteandcompileasis.

//Mainfunction

voidmain(void)


u8slaveAxis;//Slaveaxisnumber

u8master;//Gearmaster


i32synchronizationPosition=0;//Synchronizationposition

i32correctionPoint=500;//Pointwherethecorrectioncanbeapplied

i32cyclePosition=2000;//Onerevolutionis2000counts

i32currentPosition;//Thecurrentslaveposition

i32capturedPosition;//Thepositionatwhichthetriggerhappens

u16axisStatus;





///////////////////////////////

//SettheboardID

boardID=1;

//Settheaxisnumber

slaveAxis=1;

//Masterisencoder4

master=NIMC_ENCODER4;

////////////////////////////////

//--------------------------------------------------------

//Setupthegearingconfigurationfortheslaveaxis

//--------------------------------------------------------

//ConfigureGearMaster

err=flex_config_gear_master(boardID,slaveAxis,master);

CheckError;

//LoadGearRatio1:1

err=flex_load_gear_ratio(boardID,slaveAxis,NIMC_ABSOLUTE_GEARING,

1/*ratioNumerator*/,1/*ratioDenominator*/,0xFF);

CheckError;

//--------------------------------------------------------

//Setupthemoveparametersforthesuperimposedmove

//tobedoneonregistration

//--------------------------------------------------------


err=flex_set_op_mode(boardID,slaveAxis,NIMC_RELATIVE_TO_CAPTURE);

CheckError;

//LoadVelocityinRPM

err=flex_load_rpm(boardID,slaveAxis,100.00,0xFF);

CheckError;


err=flex_load_rpsps(boardID,slaveAxis,NIMC_BOTH,50.00,0xFF);

CheckError;

//--------------------------------------------------------

//EnableGearingonslaveaxis

//--------------------------------------------------------

err=flex_enable_gearing_single_axis(boardID,slaveAxis,NIMC_TRUE);

CheckError;

//--------------------------------------------------------

//Waitfortriggertodotheregistrationmove

//--------------------------------------------------------

for(;;)

//EnableHighspeedcaptureforslaveaxis

err=flex_enable_hs_capture(boardID,slaveAxis,NIMC_TRUE);

CheckError;

do

//Checkthehighspeedcapturestatus/followingerror/axisoffstatus

err=flex_read_axis_status_rtn(boardID,slaveAxis,&axisStatus);

CheckError;



CheckError;




CheckError;

while(!(axisStatus&NIMC_HIGH_SPEED_CAPTURE_BIT)&&!(axisStatus&NIMC_FOLLOWING_ERROR_BIT)&&!(axisStatus&NIMC_AXIS_OFF_BIT));//


break;//Breakoutoftheforloop

//Updatethevariablesforthiscycle

synchronizationPosition+=cyclePosition;

correctionPoint+=cyclePosition;

//Readthecapturedposition

err=flex_read_cap_pos_rtn(boardID,slaveAxis,&capturedPosition);

CheckError;

//Loadthetargetpositionfortheregistration(superimposed)move

err=flex_load_target_pos(boardID,slaveAxis,(synchronizationPosition-capturedPosition),0xFF);

CheckError;

//Waituntilwehavepassedthecorrectionpointbeforeweapplythecorrection

currentPosition=0;

while(currentPosition<correctionPoint)

err=flex_read_pos_rtn(boardID,slaveAxis,&currentPosition);

CheckError;

//Startregistrationmoveontheslave

err=flex_start(boardID,slaveAxis,0);

CheckError;

//Forloop


/////////////////////////////////////////////////////////////////////////

//ErrorHandling

//




do







TuningServoSystemsWhenyourmotioncontrolsystemincludesaservomotor,youmusttuneandcalibratethesystemtoensureproperperformance.Thischaptercoversgeneralinformationabouttuningandcalibratingyourservosystemusingcontrolloopparameters.RefertotheTuningServoMotorssectionoftheMeasurement&AutomationExplorerHelpforMotionformoreinformationaboutandinstructionsfortuningservomotorsinMeasurement&AutomationExplorer(MAX).

NoteThissectiondoesnotapplyifyouareusingtheNISoftMotionControllerbecausethecontrolloopisimplementedonthedrive.RefertothedrivedocumentationforinformationabouttuningtheservomotorsyouareusingwiththeCANopendrive.

UsingControlLoopstoTuneServoMotorsTuningmaximizestheperformanceofyourservomotors.Aservosystemusesfeedbacktocompensateforerrorsinpositionandvelocity.Forexample,whentheservomotorreachesthedesiredposition,itcannotstopinstantaneously.Thereisanormalovershootthatmustbecorrected.Thecontrollerturnsthemotorintheoppositedirectionfortheamountofdistanceequaltothedetectedovershoot.However,thiscorrectivemovealsoexhibitsasmallovershoot,whichmustalsobecorrectedinthesamemannerasthefirstovershoot.Aproperlytunedservosystemexhibitsovershootasshownthefollowingfigure.

Theamountoftimerequiredforthemotorstosettleonthecommandedpositioniscalledthesettlingtime.Bytuningtheservomotors,youcanaffectthesettlingtime,theamountofovershoot,andvariousotherperformancecharacteristics.

ControlLoopNImotionservocontrolusescontrolloopstocontinuouslycorrecterrorsinpositionandvelocity.YoucanconfigurethecontrollooptoperformaProportional,IntegralandDerivative(PID)looporamoreadvancedcontrolloop,suchasthevelocityfeedback(PIV)orvelocityfeedforward(PIVff)loops.

PIDLoopDescriptionsThefollowingarecommonvariablesrelatingtothePIDcontrolloop.Kp(ProportionalGain)Theproportionalgain(Kp)determinesthecontributionofrestoringforcethatisdirectlyproportionaltothepositionerror.Thisrestoringforcefunctionsinmuchthesamewayasaspringinamechanicalsystem.Eachsampleperiod,thePIDloopcalculatesthepositionerror,whichisthedifferencebetweentheinstantaneoustrajectorypositionandtheprimaryfeedbackposition,andmultipliesthepositionerrorbyKptoproducetheproportionalcomponentofthe16-bitDACcommandoutput.AnaxiswithtoosmallavalueofKpisunabletoholdtheaxisinpositionandisverysoft.IncreasingKpstiffenstheaxisandimprovesitsdisturbancetorquerejection.However,toolargeavalueofKpoftenresultsininstability.Ki(IntegralGain)Theintegralgain(Ki)determinesthecontributionofrestoringforcethatincreaseswithtime,ensuringthatthestaticpositionerrorintheservoloopisforcedtozero.Thisrestoringforceworksagainstconstanttorqueloadstohelpachievezeropositionerrorwhentheaxisisstopped.Eachsampleperiod,thepositionerrorisaddedtotheaccumulationofpreviouspositionerrorstoformanintegrationsum.Thisintegrationsumisscaledbydividingby256priortobeingmultipliedbyKi.Inapplicationswithsmallstatictorqueloads,thisvaluecanbeleftatitsdefaultvalueofzero(0).Forsystemshavinghighstatictorqueloads,thisvalueshouldbetunedtominimizepositionerrorwhentheaxisisstopped.Althoughnon-zerovaluesofKicausereducedstaticpositionerror,theytendtocauseincreasedpositionerrorduringaccelerationanddeceleration.ThiseffectcanbemitigatedthroughtheuseoftheIntegrationLimitparameter.ToohighavalueofKioftenresultsinservoloopinstability.NationalInstrumentsthereforerecommendsthatyouleaveKiatitsdefaultvalueofzerountiltheservosystemoperationisstable.ThenyoucanaddasmallamountofKitominimizestaticpositionerrors.

Kd(DerivativeGain)Thederivativegain(Kd)determinesthecontributionofrestoringforceproportionaltotherateofchange(derivative)ofpositionerror.Thisforceactsmuchlikeviscousdampinginadampedspringandmassmechanicalsystem.Ashockabsorberisanexampleofthiseffect.ThePIDloopcomputesthederivativeofpositionerroreveryderivativesampleperiod.Anon-zerovalueofKdisrequiredforallsystemsthatusetorqueblockamplifiers,wherethecommandoutputisproportionaltomotortorque,fortheservoloopoperationtobestable.ToosmallaKdvalueresultsinservoloopinstability.Withvelocityblockamplifiers,wherethecommandoutputisproportionaltomotorvelocity,itistypicaltosetKdtozerooraverysmallpositivevalue.Kv(VelocityFeedback)Youcanuseaprimaryorsecondaryfeedbackencoderforvelocityfeedback.Settingthevelocityfeedbackgain(Kv)toavalueotherthanzero(0)enablesvelocityfeedbackusingthesecondaryencoder,ifconfigured,ortheprimaryencoderifasecondaryencoderisnotconfigured.Kvisusedtoscalethisvelocityfeedbackbeforeitisaddedtotheothercomponentsinthe16-bitDACcommandoutput.Kvissimilartoderivativegain(Kd)exceptthatitscalesthevelocityestimatedfromencoderresourcesonly.Thederivativegainscalesthederivativeofthepositionerror,whichisthedifferencebetweentheinstantaneoustrajectorypositionandtheprimaryfeedbackposition.LiketheKdterm,thevelocityfeedbackderivativeiscalculatedeveryderivativesampleperiodandthecontributionisupdatedeveryPIDsampleperiod.Velocityfeedbackisestimatedthroughacombinationofspeed-dependentalgorithms.Velocityismeasuredbasedonthetimeelapsedbetweeneachencodercount.Vff(VelocityFeedforward)Thevelocityfeedforwardgain(Vff)determinesthecontributioninthe16-bitDACcommandoutputthatisdirectlyproportionaltotheinstantaneoustrajectoryvelocity.ThisvalueisusedtominimizefollowingerrorduringtheconstantvelocityportionofamoveandcanbechangedatanytimetotunethePIDloop.

Velocityfeedforwardisanopen-loopcompensationtechniqueandcannotaffectthestabilityofthesystem.However,ifyouusetoolargeavalueforVff,followingerrorcanreverseduringtheconstantvelocityportion,thusdegradingperformance,ratherthanimprovingit.VelocityfeedforwardistypicallyusedwhenoperatinginPIVffmodewitheitheravelocityblockamplifierorsubstantialamountofvelocityfeedback(Kv).Inthesecases,theuncompensatedfollowingerrorisdirectlyproportionaltothedesiredvelocity.Youcanreducethisfollowingerrorbyapplyingvelocityfeedforward.Increasingtheintegralgain(Ki)alsoreducesthefollowingerrorduringconstantvelocitybutonlyattheexpenseofincreasedfollowingerrorduringaccelerationanddecelerationandreducedsystemstability.Forthesereasons,increasingKiisnotarecommendedsolution.

TipInPIVffmode,theKdandKvgainsaresettozero.

VelocityfeedforwardisrarelyusedwhenoperatinginPIDmodewithtorqueblockamplifiers.Inthiscase,becausethefollowingerrorisproportionaltothetorquerequired,ratherthanthevelocity,itistypicallymuchsmalleranddoesnotrequirevelocityfeedforward.Aff(AccelerationFeedforward)Theaccelerationfeedforwardgain(Aff)determinesthecontributioninthe16-bitDACcommandoutputthatisdirectlyproportionaltotheinstantaneoustrajectoryacceleration.Affisusedtominimizefollowingerror(positionerror)duringaccelerationanddecelerationandcanbechangedatanytimetotunethePIDloop.Accelerationfeedforwardisanopen-loopcompensationtechniqueandcannotaffectthestabilityofthesystem.However,ifyouusetoolargeavalueofAff,followingerrorcanreverseduringaccelerationanddeceleration,thusdegradingperformance,ratherthanimprovingit.KdacKdacistheDigitaltoAnalogConverter(DAC)gain.UsethefollowingequationtocalculateKdac:

20Vrepresentsthe±10Vrangeinthemotioncontroller.Ga

GaistheAmplifierGain.KtKtistheTorqueConstantofthemotor.KtisrepresentedinNewtonMetersperAmp.1/J1/Jrepresentsthemotorplusloadinertiaofthemotionsystem.KeKerepresentstheconversionfactortorevolutions.Thismayinvolveascalingfactor.

DualLoopFeedbackMotioncontrolsystemsoftenusegearstoincreaseoutputtorque,increaseresolution,orconvertrotarymotiontolinearmotion.Themaindisadvantageofusinggearsisthebacklashcreatedbetweenthemotorandtheload.Thisbacklashcancausealossofpositionaccuracyandsysteminstability.Thecontrollooponthemotionsystemcorrectsforerrorsandmaintainstightcontroloverthetrajectory.Thecontrolloopconsistsofthreemainparts—proportional,integralandderivative—knownasPIDparameters.Thederivativepartestimatesmotorvelocitybydifferentiatingthefollowingerror(positionerror)signal.Thisvelocitysignaladds,totheloop,dampingandstability.Ifbacklashispresentbetweenthemotorandthepositionsensor,thepositionsofthemotorandthesensorarenolongerthesame.Thisdifferencecausesthederivedvelocitytobecomeineffectiveforloopdampingpurposes,whichcreatesinaccuracyinpositionandsysteminstability.Usingtwopositionsensorsforanaxiscanhelpsolvetheproblemscausedbybacklash.Asshowninthefollowingfigure,onepositionsensorresidesontheloadandtheotheronthemotorbeforethegears.Themotorsensorisusedtogeneratetherequireddampingandtheloadsensorforpositionfeedback.Themixofthesetwosignalsprovidesthecorrectpositionfeedbackwithdampingandstability.

TipYoucanenabledual-loopfeedbackontheNImotioncontrollerbymappinganencoderasthesecondaryfeedbackfortheaxis,andthenusingthevelocityfeedbackgaininsteadofthederivativegaintodampenandstabilizethesystem,asshowninthefollowingfigure.

VelocityFeedbackYoucanconfiguretheNImotioncontrollerforvelocityfeedbackusingtheKv(velocityfeedback)gain.UsingKvcreatesaminorvelocityfeedbackloop.Thisisverysimilartothetraditionalanalogservocontrolmethodofusingatachometerforclosingthevelocityloop.Thistypeoffeedbackisnecessaryforsystemswhereprecisespeedcontrolisessential.Youcanusealessexpensivestandardtorque,orcurrentmode,amplifierwiththevelocityfeedbacklooponNImotioncontrollerstoachievethesameresultsyouwouldgetfromusingvelocityamplifiers,asshowninthefollowingfigure.

Settinganynon-zerovalueforKvallowsyoutousetheKvterminsteadoforinadditiontotheKdtermtostabilizethesystem.Velocityfeedbackgain(Kv)issimilartoderivativegain(Kd)exceptthatitscalesthevelocityestimatedfromencoderresourcesonly.Thederivativegainscalesthederivativeofthepositionerror,whichisthedifferencebetweentheinstantaneoustrajectorypositionandtheprimaryfeedbackposition.LiketheKdterm,thevelocityfeedbackderivativeiscalculatedeveryderivativesampleperiod,andthecontributionisupdatedeveryPIDsampleperiod,asshowninthefollowingfigure.

NIMotionControllerswithVelocityAmplifiersVelocityamplifiersclosethevelocityloopusingatachometerontheamplifieritself,asshowninthefollowingfigure.Inthiscase,thecontrollermustensurethatthevoltageoutputisproportionaltothevelocity.Usethevelocityfeedforwardterm(Vff)toensurethatthereisminimumfollowingerrorduringtheconstantvelocityprofiles.

ThefollowingfiguredescribeshowtouseNImotioncontrollerswithvelocityamplifiers.

Youtypicallyusevelocityfeedforwardwhenusingcontrollerswithvelocityamplifiers.Theuncompensatedfollowingerrorisdirectlyproportionaltothespecifiedvelocity.Youcanreducethefollowingerrorbyapplyingvelocityfeedforward.Increasingtheintegralgain(Ki)alsoreducesthefollowingerrorduringconstantvelocity,butattheexpenseofincreasedfollowingerrorduringaccelerationanddecelerationandreducedsystemstability.

NoteNationalInstrumentsdoesnotrecommendincreasingKi.

VelocityfeedforwardisrarelyusedwhenoperatinginPIDmodewithtorqueblockamplifiers.Inthiscase,followingerroristypicallymuchsmallerbecauseitisproportionaltothetorquerequiredratherthantothevelocity.WhenoperatinginPIDmodewithtorqueblockamplifiers,velocityfeedforwardisnotrequired.

SinusoidalCommutationforBrushlessServoMotionControlSinusoidalcommutationallowsyoutouselessexpensiveservomotordriveswithNImotioncontrollersthatsupportthisfeature.

PhaseInitializationDeterminingtheCountsperElectricalCycleoftheMotorCommutationFrequencyTroubleshootingHallEffectSensorConnections

PhaseInitializationWhenthesystemisfirstpoweredon,thecontrollermustdeterminetheinitialcommutationphase.NImotioncontrollerssupportseveralmethodsofphaseinitialization,includingHalleffectsensors,shakeandwake,anddirectset.

HallEffectSensorsThecontrollercanuseHalleffectsensorstoestimatethecommutationphasebasedonthestateofthesensors.AfteraHalleffectstatetransitionoccurs,thecontrollerrecalculatesthephaseanglebasedonthetransitionlocation.Toobtainmaximumtorqueatthebeginningofthemove,performamovethatis1/6thofthemagneticcycleaftersysteminitialization.RefertothehardwaredocumentationforHalleffectsensortypesandconnectionschemes.

ShakeandWake"Shakeandwake"isaninitializationmethodwherethemotioncontrolleroutputsaspecifiedvoltageforaspecifiedduration.Thisdrivesthesystemtothezero-degreephasepositionandallowsyoutoestablishthepositionasabaselineforallotherphasepositions.Duringthisprocess,themotormovestothezero-degreepositionwithhightorque.Ensurethesystemisawayfromanylimitsbeforeperformingshakeandwakeinitialization.Ifthesystemhasloadorismovingagainstgravity,increasetheshakeandwakevoltage.Ifthereissignificantjitterastheaxisapproacheszero,increasetheduration.

DirectSetDirectsetisaninitializationmethodwherethecontrollersetsthecurrentpositionasthespecifiedphaseangle.Thisinitializationmethodisrecommendedonlyforacustomsystemwithknowninitialphaseangle.Whenevertheaxisisenabled,thecontrollermustperformthephaseinitializationproceduretodeterminethephase.

DeterminingtheCountsperElectricalCycleoftheMotorThecontrollerneedstoknowthecountsperelectricalcycleofthemotortodeterminethecommutationphase.Themotormanufacturerusuallygivesthisspecification.Inmanycases,theinformationalsomaybespecifiedasthenumberofpoles.Toconvertfromthenumberofpolestothenumberofcountsperelectricalcycle,usethefollowingformula:

countsperelectricalcycle=CautionCountsperelectricalcyclemustbesetcorrectlytoavoidoverheatinganddamagingyourmotor.

CommutationFrequencyThecontrollerupdatesthecommandvoltageandthecommutationphaseeveryupdateperiod.Tocommutatebrushlessmotorssmoothly,thecontrollermustupdatethephaseatleastsixtimesperelectricalcycle.Therefore,thecommutationfrequencyislimitedbytheupdaterateofthecontrolloop.TocalculatethemaximumcommutationfrequencysupportedataparticularPIDupdaterate,usethefollowingformula:

commutationfrequency=

TroubleshootingHallEffectSensorConnectionsCompletethefollowingstepsifyouhaveproblemswithHalleffectsensorconnections.

1. Checkthemanualsthatshippedwiththehardwareforconnectionprocedures.

2. Performa"shakeandwake"phaseinitialization.Duringthisprocess,themotorisdriventothezerodegreephasepositionwiththecommandedvoltage.Makesurethemotorisclearofanylimitsbeforeyoustart.

3. RecordtheHalleffectsensorsstatesbyreadingtheDIOlinesconnectedtotheHallsensors.RefertothehardwaredocumentationfortheHalleffectsensorlines.ThisisthestateoftheHalleffectsensorsatthezero-degreephaseposition.

4. Commandthemotortomoveforwardataslowvelocity.RecordthestateoftheHalleffectsensorsateachstatetransition.ThestateoftheHalleffectsensorsshouldreturntothestaterecordedinstep2aftersixstatetransitions.

5. UsetheHallsensorstransitionstateastheHallsensorsdiagram.RefertothehardwaredocumentationformoreinformationonHallsensordiagrams.Followtheprocedureoutlinedinthehardwaredocumentation.

SwitchingFeedbackontheFly(NI7350Only)NI7350devicesallowswitchingbetweenfeedbackdeviceswithoutdisablingtheaxis,suchaswhenswitchingbetweenencoderandanalogfeedback.Completethefollowingstepstoconfigureyoursystemforswitchingfeedbackdevicesonthefly:

1. TunethesystemwiththefirstfeedbackdeviceinMAX.2. TunethesystemwiththesecondfeedbackdeviceinMAX.3. StorethefirstsetofPIDgainsusingtheLoadAllPIDParameters

VIorfunction.4. StorethesecondsetofPIDgainsusingtheLoadAllPID

ParametersVIorfunction,followingtheinstructionsintheLoadingaSecondSetofPIDParameterssectionofthetopic.

5. EnablethecontrollertousethesecondsetofPIDparameterswhenswitchingfeedbackontheflyusingtheLoadAdvancedControlParameterVIorfunction.

6. UsetheConfigureAxisResourcesVIorfunctiontoconfiguretheaxistousethefirstfeedbackdevice.

Toswitchbetweenthefirstandsecondfeedbackdevices,callConfigureAxisResourceswiththeotherfeedbackdevicewhentheaxisisnotmoving.

NI-MotionCReferenceHelp.chm::/flex_load_pid_parameters.html

NI-MotionCReferenceHelp.chm::/flex_load_advanced_control_parameter.html

NI-MotionCReferenceHelp.chm::/flex_config_axis.html

InitializingtheControllerProgrammaticallyYoucaninitializethemotioncontrollerfromwithinaLabVIEW,VisualBasic,orC/C++program,inadditiontoinitializingcontrollersinMeasurement&AutomationExplorer(MAX).RefertothefollowingtableforthestepsyoumusttaketoinitializeacontrollerprogrammaticallyandthefunctionsandVIsyouuseforeachstep.

Step Functionand/orVI1. Clearthe

power-upstate.

UsetheClearPowerUpStatusVIorfunction.

2. Reviewanyerrorsthatoccurredonthecontrollertodeterminehowbesttohandlethem.

UsetheReadErrorMessageVIorfunction.

3. Makesureallaxesarestoppedanddisabled.

UsetheStopMotionVIorfunctionandEnableAxesVIsorfunctions.IntheStopMotionVIorfunction,setStopType(Decel)settoHalt.IntheEnableAxesVIorfunction,setAxisBitmaptoFalseforeachaxisyouwanttodisable.

4. Unconfigurevectorspaces.

UsetheConfigureVectorSpaceVIorfunctionwiththeXAxis,YAxis,andZAxisinputssettoNone.

5. Configureresourcesforaxes.

UsetheConfigureAxisResourcesVIorfunction.

6. Loadallaxisconfigurationoptionsyouwanttouse.

UsetheAxis&ResourceConfigurationVIsorfunctions.

NI-MotionCReferenceHelp.chm::/flex_clear_pu_status.html

NI-MotionCReferenceHelp.chm::/flex_read_error_msg_rtn.html


NI-MotionCReferenceHelp.chm::/flex_enable_axis.html

NI-MotionCReferenceHelp.chm::/flex_config_vect_spc.html

NI-MotionCReferenceHelp.chm::/flex_config_axis.html

NI-MotionCReferenceHelp.chm::/AxisResourceConfigurationFunctions.html

7. InitializeencodersandADCs,asappropriate.

UsetheappropriateVIsorfunctionsontheAnalog&DigitalI/Opalette.

8. Enabletheaxes,butleavethemdeactivated.

UsetheEnableAxesVIorfunction.

9. Loadtheappropriatecontrolloopparameters.

UsetheLoadAdvancedControlParameterVIorfunctionandeitherLoadSinglePIDParameterVIorfunctionorLoadAllPIDParametersVIorfunction.

10. Callhaltonallaxestoactivatethem.

UsetheStopMotionVIorfunctionwithStopType(Decel)settoHaltstop.

11. Configurecaptureandcomparesettings.

UsetheVIsorfunctionsontheMotionI/Opalettetoconfigurethecaptureandcomparesettings.

12. Configurethefollowingoptionalsettings:

ConfiguretrajectorysettingsConfigurefindreferencesettingsConfigureDIOsettingsConfigure

UsethefollowingpalettesorVIs/functionstoconfiguretheoptionalsettings:

TrajectoryControlVIsorfunctionsFindReferenceVIsorfunctionsAnalog&DigitalI/OVIsorfunctionsConfigurePWMOutputVIorfunctionandLoadPWMDutyCycleVIorfunctionGearingVIsorfunctions

NI-MotionCReferenceHelp.chm::/AnalogDigitalIOFunctions.html

NI-MotionCReferenceHelp.chm::/flex_load_advanced_control_parameter.html

NI-MotionCReferenceHelp.chm::/flex_load_single_pid_parameter.html

NI-MotionCReferenceHelp.chm::/flex_load_pid_parameters.html

NI-MotionCReferenceHelp.chm::/MotionI_OFunctions.html

NI-MotionCReferenceHelp.chm::/TrajectoryControlFunctions.html

NI-MotionCReferenceHelp.chm::/FindReferenceFunctions.html

NI-MotionCReferenceHelp.chm::/AnalogDigitalIOFunctions.html

NI-MotionCReferenceHelp.chm::/flex_configure_pwm_output.html

NI-MotionCReferenceHelp.chm::/flex_load_pwm_duty.html

NI-MotionCReferenceHelp.chm::/GearingFunctions.html

PWMsettingsGearing

UsingtheMotionControllerwiththeLabVIEWReal-TimeModuleUsingNI-Motiononareal-time(RT)systemisdesignedtobealmosttransparentforanyonefamiliarwithNI-Motion.UsingNI-MotionwithRTrequiresthefollowinghardwareandsoftware:

NIPXIchassiswithanavailablePXIslotNIPXIMotioncontrollerHostcomputerLabVIEWReal-TimeModuleOneofthefollowingmotionsoftwareoptions:

NI-Motion(73xxcontrollersupport)NISoftMotionController

RefertotheRemoteSystemsandNI-MotiontopicintheMeasurement&AutomationExplorerHelpforMotionfordetailedinstructionsaboutconfiguringtheNImotioncontrolleronaremotePXIchassis.

GlossaryPrefixes Numbers/Symbols A B C D E F G H I J

K L M N O P Q R S T U V W Z

PrefixesSymbol Prefix Valuep pico 10-12

n nano 10-9

µ micro 10-6

m milli 10-3

k kilo 103

M mega 106

G giga 109

T tera 1012

Numbers/SymbolsnV nanovolts 10-9volts

µV microvolts 10-6volts

µΩ microohms 10-6ohms

mΩ milliohms 10-3ohms

MΩ megaohms 106ohms

pA picoamps 10-12amperes

nA nanoamps 10-9amperes

µA microamps 10-6amperes

mA milliamps 10-3amperes

A

A amperesA/D analog-to-digitalabsolutemode Treatthetargetpositionloadedasposition

relativetozero(0)whilemakingamove.absoluteposition Positionrelativetozero.acceleration/deceleration Measurementofthechangeinvelocityasa

functionoftime.Accelerationanddecelerationdescribestheperiodwhenvelocityischangingfromonevaluetoanother,suchasfromastop(zerovelocity)toaspecifiedspeed(targetvelocity)orviceversa.Decelerationisalsoconsiderednegativeacceleration.

activeclosed Asignalisactivewhencurrentisflowingthroughtheoptocoupledinput.

activehigh Signalisactivewhenitsvaluegoeshigh(1).Seealsonon-inverting.

activelow Signalisactivewhenitsvaluegoeslow(0).Seealsoinverting.

activeopen Asignalisactivewhencurrentisnotflowingthroughtheoptocoupledinput.

ADC analog-to-digitalconverteraddress Charactercodethatidentifiesaspecific

location,orseriesoflocations,inmemoryoronahostPCbussystem.

amplifier Drivethatdeliverspowertooperatethemotorinresponsetocontrolsignals.Ingeneral,theamplifierisdesignedtooperatewithaparticularmotortype.Forexample,youcannotuseastepperdrivetooperateaDCbrushmotor.

API applicationprogramminginterface

axis Unitthatcontrolsamotororanysimilarmotionorcontroldevice.

B

b bit—Onebinarydigit,either0or1.baseaddress

MemoryaddressthatservesasthestartingaddressforprogrammableorI/Obusregisters.Allotheraddressesarelocatedbyaddingtothebaseaddress.

binary Numbersystemwithabaseof2.blending Blendingconnectsmovesegmentswhilemaintainingvelocity

withinthegivenphysicalconstraints.Theseconstraintsarethespecificmovesegmentsbeingblended,forexample,velocity,acceleration,deceleration,ands-curveforeachmove.

buffer Temporarystorageforacquiredorgenerateddata(insoftware).

bus Groupofconductorsthatinterconnectindividualcircuitryinacomputer.Typically,abusistheexpansionvehicletowhichI/Oorotherdevicesareconnected.ExamplesofPCbusesaretheISAandPCIbus.

byte Eightrelatedbitsofdata,an8-bitbinarynumber.Alsousedtodenotetheamountofmemoryrequiredtostoreonebyteofdata.

C

CCW counterclockwise—Impliesthedirectionthemotorrotatesin.

closed-loop Broadlyappliedtermrelatingtoanysystemwhereoutputismeasuredandcomparedtoinput.Theoutputisthenadjustedtoreachtheappropriatecondition.Inmotioncontrolthistermappliestoamotionsystemthatusesafeedbackdevicetoprovidepositionandvelocitydataforstatusreportingandaccuratelycontrollingpositionandvelocity.

commutation Sequentialcontrolofswitchedwaveformsfromthepowerdriveramplifierintothemotorphasewindingsthatcausesrotationorlinearmotiondependingonmotortype.Brushtypemotorsauto-commutateduetothebrushcontactwiththemotorwindings.Brushlesstypemotorsrequiretheadvanceinformationofpositionanddirectiontoaccuratelyprovidecorrectwaveformswitchingsequences.Brushlessmotorstypicallyusehall-effecttypesensorstogeneratethecommutationcontrolwaveforms.

controlsystembandwidth

Measureofaclosed-loopsystem'sresponseandistypicallyrepresentedasafrequencyrangeoranupdateperiodforthePIDloopinadigitalservocontroller.Forexample,ifaPIDloophasanupdaterateof250µs,itwouldhaveabandwidthof4kHz.

CPU centralprocessingunitCSR communicationsstatusregisterCW clockwise—Impliesthedirectionthemotorrotatesin.

D

DAC digital-to-analogconverterdataacquisition

Theprocessofcollectingandmeasuringelectricalsignalsfromsensors,transducers,andtestprobesorfixturesandinputtingthemtoacomputerforprocessing.

DC directcurrentDGND digitalgrounddigitalI/Oport

Groupofdigitalinput/outputsignals.

DIP dualinlinepackageDLL DynamiclinklibraryforWindows.ProvidestheAPIforthe

motioncontroldevices.drive Electronicsignalamplifierthatconvertsmotorcontrol

commandsignalsintohigher-voltagesignalssuitablefordrivingmotors.

driver SoftwarethatcontrolsaspecifichardwaredevicesuchasaDAQboardoramotioncontroller.

E

encoder Devicethattranslatesmechanicalmotionintoelectricalsignals;usedformonitoringpositionorvelocityinaclosed-loopsystem.

encoderresolution

NumberofencoderlinesbetweenconsecutiveencodermarkerorZ-bitindexes.Iftheencoderdoesnothaveanindexoutputtheencoderresolutioncanbereferredtoaslinesperrevolution.

F

F faradFIFO First-in-first-outmemorybuffer—thefirstdatastoredisthe

firstdatasenttotheacceptor.FIFOsareoftenusedonDAQdevicestotemporarilystoreincomingoroutgoingdatauntilthatdatacanberetrievedoroutput.Forexample,ananaloginputFIFOstorestheresultsofA/Dconversionsuntilthedatacanberetrievedintosystemmemory,aprocessthatrequirestheservicingofinterruptsandoftentheprogrammingoftheDMAcontroller.Thisprocesscantakeseveralmillisecondsinsomecases.Duringthistime,dataaccumulatesintheFIFOforfutureretrieval.WithalargerFIFO,longerlatenciescanbetolerated.Inthecaseofanalogoutput,aFIFOpermitsfasterupdaterates,becausethewaveformdatacanbestoredontheFIFOaheadoftime.ThisagainreducestheeffectoflatenciesassociatedwithgettingthedatafromsystemmemorytotheDAQdevice.

filterparameters

Indicatesthecontrolloopparametergains(PIDgains)foragivenaxis.

filtering Typeofsignalconditioningthatfiltersunwantedsignalsfromthesignalbeingmeasured.

flashROM Typeofelectricallyreprogrammableread-onlymemory.followingerrortrippoint

Thedifferencebetweentheinstantaneouscommandedtrajectorypositionandthefeedbackposition.Ifthefollowingerrorincreasesbeyondthemaximumallowablevalueentered—referredtoasthefollowingerrortrippoint—themotortripsonfollowingerrorandiskilled,preventingtheaxisfromrunningaway.

freewheel Conditionofamotorwhenpowerisde-energizedandthemotorshaftisfreetoturnwithonlyfrictionalforcestoimpedeit.

full-step Full-stepmodeofasteppermotor—Foratwo-phasemotor,thisreferstoenergizingtwowindingsorphasessimultaneously.

G

Gnd groundGND ground

H

half-step Modeofasteppermotor—Foratwophasemotor,thisreferstoalternatelyenergizingtwowindingsandthenonlyone.Inhalfstepmode,alternatestepsarestrongandweak,butthereissignificantimprovementinlow-speedsmoothnessoverthefull-stepmode.

hex hexadecimalholdingtorque

Forcethatamotorcanprovideorwithstandwhilestillremaininginafixedstoplocationwithoutanyrotation,translationormovement.

homeswitch/homeposition(input)

Referencepositioninamotioncontrolsystemderivedfromamechanicaldatumorswitch.Oftendesignatedasthezeropositioninanabsolutepositionframeofreference.Themotioncontrollerhaltsthemotorifitfindsthisswitchactivewhileperformingafindhomesequence.

hostcomputer

Computerinwhichthemotioncontrollerisinstalled,orthatiscontrollingtheremotesysteminwhichthemotioncontrollerisinstalled.

hybridsteppermotor

Motortypedesignedtomoveindiscretestepincrements,(typicallyspecifiedindegrees).Hybridsteppermotorshavepermanentmagnetrotorelementswithacoilwoundstator(outershell)andnobrushescontactingbetweenthetwo.Thecurrentthroughthecoilphasesisswitchedinapredeterminedsequence(commutated)toproducetheappropriatemotioninagivendirection.

Hz hertz—thenumberofscansreadorupdateswrittenpersecond.

I

I/O input/output—Thetransferofdatatoandfromacomputersysteminvolvingcommunicationschannels,operatorinterfacedevices,dataacquisition,and/ormotioncontrolinterfaces.

ID identificationimportlibrary

Windows-specificfilethatcontainsinformationabouttheVIscontainedinacompaniondynamiclinklibrary(DLL).Windowsapplicationsaretypicallylinkedtooneormoreimportlibraries.

in inchesindex Markerbetweenconsecutiveencoderrevolutions.inverting Definesthepolarityofaswitch(limitswitch,homeswitch,and

soon)whenitisinitsactivestate.Iftheseinputsareactivelowtheyaresaidtohaveinvertingpolarity.Seealsoactivelow.

IRQ interruptrequestISA industry-standardarchitecture

Jjerk Derivativeofacceleration(changeofaccelerationperunittime)

measuredinunitsofcounts(steps)/s3.

K

k kilo—Thestandardmetricprefixfor1,000,or103,usedwithunitsofmeasuresuchasvolts,hertz,andmeters.

K kilo—Theprefixfor1,024,or210,usedwithBinquantifyingdataorcomputermemory.

L

latching Signalthatmaintainsitsvaluewhileinagivenstate,asopposedtoasignalthatmomentarilypulseswhenenteringorexitingastate.

LIFO last-in,first-outlimitswitch/end-of-travelposition(input)

Sensorsthatalertthecontrolelectronicsthatthephysicalendoftravelisnearandthatthemotionmuststop.

M

m metersMCS MoveCompleteStatusmicrostep Proportionalcontrolofenergyinthecoilsofasteppermotor

thatallowsthemotortomovetoorstopatlocationsotherthanthefixedmagnetic/mechanicalpolepositionsdeterminedbythemotorspecifications.Thiscapabilityfacilitatesthesubdivisionoffullmechanicalstepsonasteppermotorintofinermicrosteplocationsthatgreatlysmoothmotorrunningoperationandincreasetheresolutionornumberofdiscretepositionsthatasteppermotorcanattainineachrevolution.

moduloposition

Treatthepositionasifitiswithintherangeoftotalquadraturecountsperrevolutionforanaxis.

MustOff Stateorbitthatisforcedoff(False)ormustbeofftosatisfyacondition.

MustOn Stateorbitthatisforcedon(True)ormustbeontosatisfyacondition.

N

noise Anundesirableelectricalsignal.NoisecomesfromexternalsourcessuchastheACpowerline,motors,generators,transformers,fluorescentlights,solderingirons,CRTdisplays,computers,electricalstorms,welders,radiotransmitters,andinternalsourcessuchassemiconductors,resistors,andcapacitors.Noisecorruptssignalsyouaretryingtosendorreceive.

non-inverting

Definesthepolarityofaswitch(limitswitch,homeswitch,andsoon)whenitisinitsactivestate.Iftheseinputsareactivehightheyaresaidtohavenon-invertingpolarity.Seealsoactivehigh.

O

opencollector

Methodofoutputcapableofsinkingcurrent,butnotsourcingcurrent.

open-loop

Referstoamotioncontrolsystemwherenoexternalsensors,orfeedbackdevices,areusedtoprovidepositionorvelocitycorrectionsignals.

P

packets Commandanddatasentasagroupoveracomputerbus.

PCI peripheralcomponentinterconnect—Ahigh-performanceexpansionbusarchitectureoriginallydevelopedbyInteltoreplaceISAandEISA.PCIisachievingwidespreadacceptanceasastandardforPCsandworkstations;itoffersatheoreticalmaximumtransferrateof132MB/s.

phaseangle/phasemargin

ValuepresentedinPIDLoopTuningBodePlotanalysisthatrepresentstheadvanceorleadofaninputsignaltotheoutputsignalinaclosed-loopservocontroller.Usedtodetermineclosed-loopsystemstabilityatagivencrossoverfrequency.

PIDcontrolloop

proportional-integral-derivativecontrolloop—Acontrolmethodinwhichthecontrolleroutputisproportionaltotheerror,theerrortimehistory,andtherateatwhichtheerrorischanging.Theerroristhedifferencebetweentheobservedandthecommandedvaluesofavariablethatisundercontrolaction.

PIDlooptuning/servocompensation

FlexibleadjustmentoftheProportional,Integral,andDerivativeGainParametersalongwithloopupdaterateorfrequencytoassurestableoperationandappropriatedynamicresponseofaclosed-loopservosystem.

PIVffcontrolloop

proportional-integral-velocityfeedforwardcontrolloop—Acontrolmethodthatoperateswithzeroderivativegainandeithervelocityfeedbackoravelocityblockamplifier.

port 1. Communicationsconnectiononacomputeroraremotecontroller.

2. Digitalport,consistingoffouroreightlinesofdigitalinput,and/oroutput.

positionbreakpoint

Allowsamotortostopatagivenpointsothatanotheraction,suchasadataacquisitionoranimageacquisition,cantakeplace.Youcansetpositionbreakpointsinabsoluteorrelativequadraturecounts.

Whentheencoderreachesapositionbreakpoint,theassociatedbreakpointoutputimmediatelytransitions.

positionresolution

Typicallydeterminedbythesmallestincrementofmotionthatcanbecontrolled.Insteppermotorsystems,itisdeterminedbythenumberofstepsperrevolution,typicallyasalimitationofthestepperdrivermicrosteppingvalueorofthefeedbackdeviceresolution.Inservomotorsystems,itisentirelydeterminedbytheresolutionofthefeedbackdeviceincountsperrevolutionofthemotor.

powercycling Turningthehostcomputeroffandthenbackon.Thisresetsthemotioncontroller.

profile Instantaneouspositionversustimeoutputofatrajectorygenerator.

pull-inmove Whensteppermotorsareruninclosed-loopmode,theencoderfeedbackisusedtoverifythepositionofanaxiswhenthemotionends.Themotioncontrollerthencommandstheaxistodoafinalmovesothatitisatthespecifiedtargetposition.

PWM pulsewidthmodulation—Methodofcontrollingtheaveragecurrentinamotorphasewindingbyvaryingtheon-time(dutycycle)oftransistorswitches.

PXI PCIeXtensionsforInstrumentation

Q

quadraturecounts

Encoderlineresolutiontimesfour.Theencoderresolutionisthenumberofencoderlinesbetweenconsecutiveencoderindexes(markerorZ-bit).Iftheencoderdoesnothaveanindexoutputtheencoderresolutioncanbereferredtoaslinesperrevolution,linesperinch,linespermillimeter,andsoon.

R

RAM random-accessmemoryRDB returndatabufferrelativebreakpoint

Setsthepositionbreakpointforanencoderinrelativequadraturecounts.

relativeposition

Destinationortargetpositionformotionspecifiedwithrespecttothecurrentlocation,regardlessofitsvalue.

relativepositionmode

Treatthetargetpositionloadedaspositionrelativetocurrentpositionwhilemakingamove.

ribboncable

Flatcableinwhichtheconductorsaresidebyside.

ROM read-onlymemory—non-volatilememoryusedforstoringcode,programs,anddata.

rotaryaxis Axisforwhichrotarycountsareloaded.Theaxismovestothetargetpositionbytakingtheshortestpath,eitherforwardorbackwards,whileremainingwithintheonerevolutiondefinedbytheloadedmodulovalue.

RPM revolutionsperminute—Unitsforvelocity.RPSPSorRPS/S

revolutionspersecondsquared—Unitsforaccelerationanddeceleration.

RTR ReadytoReceiveRTSI real-timesystemintegrationbus—theNationalInstruments

timingbusthatconnectscontrollersdirectly,bymeansofconnectorsontopofthecontrollers,forprecisesynchronizationoffunctions.

S

s,sec secondsservo 1. Specifiesanaxisthatcontrolsaservomotor.

2. Specifieswhenaservomotorbecomesactive.

sinusoidalcommutation

Methodofcontrollingcurrentinthewindingsofabrushlessservomotorbyusingthepatternofasinewavetoshapethesmoothdeliveryofcurrenttothreemotorinputs,each120°outofphasefromthenext.

slot PositionwhereamodulecanbeinsertedintoanISAorPCIbackplane.

stepoutputrate

Thefrequencyofthestepoutputcontrolpulsesgeneratedbyacontroller/indexerandprovidedtoanamplifierdriver.Thecombinationofstepoutputrate(steps/s),stepsperrevolution(steps/rev),andtime(60s/minute)provideabasicrepresentationofmotorvelocityinRPM.Linearspeedmaybefurtherderivedbyadditionalmechanicaldata,leadscrewrevolutionsperinch,andsoon.

stepper Specifiesanaxisthatcontrolsasteppermotor.

T

toggle Changingstatefromhightolow,backtohigh,andsoon.torque Forcetendingtoproducerotation.totempole Methodofoutputcapableofsinkingandsourcingcurrent.trapezoidalprofile

Typicalmotiontrajectory,whereamotoracceleratesuptotheprogrammedvelocityusingtheprogrammedacceleration,traversesattheprogrammedvelocity,andthendeceleratesattheprogrammedaccelerationtothetargetposition.

trigger Anyeventthatcausesorstartssomeformofdatacapture.triggerbufferinputs

Digitalsignalthatbeginstheexecutionofasequenceofmotioncommandsstoredonthecontroller/indexerallowingthecommandstofullyexecuteuntiltheendofthesequenceisreached.

TTL transistor-transistorlogic

UUOM unitofmeasure

V

V voltsvelocitymode Movetheaxiscontinuouslyataspecifiedvelocity.

W

watchdog Timertaskthatshutsdown,orresets,themotioncontroldeviceifanyseriouserroroccurs.

word Standardnumberofbitsthataprocessorormemorymanipulatesatonetime,typically8-bit,16-bit,or32-bit.

ZZ-bit Markerorindexbetweenconsecutiveencoderrevolutions.

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PatentsForpatentscoveringNationalInstrumentsproducts,refertotheappropriatelocation:Help»Patentsinyoursoftware,thepatents.txtfileonyourCD,orni.com/patents.

WARNINGREGARDINGUSEOFNATIONALINSTRUMENTSPRODUCTS(1)NATIONALINSTRUMENTSPRODUCTSARENOTDESIGNEDWITHCOMPONENTSANDTESTINGFORALEVELOFRELIABILITYSUITABLEFORUSEINORINCONNECTIONWITHSURGICALIMPLANTSORASCRITICALCOMPONENTSINANYLIFESUPPORTSYSTEMSWHOSEFAILURETOPERFORMCANREASONABLYBEEXPECTEDTOCAUSESIGNIFICANTINJURYTOAHUMAN.(2)INANYAPPLICATION,INCLUDINGTHEABOVE,RELIABILITYOFOPERATIONOFTHESOFTWAREPRODUCTSCANBEIMPAIREDBYADVERSEFACTORS,INCLUDINGBUTNOTLIMITEDTOFLUCTUATIONSINELECTRICALPOWERSUPPLY,COMPUTERHARDWAREMALFUNCTIONS,COMPUTEROPERATINGSYSTEMSOFTWAREFITNESS,FITNESSOFCOMPILERSANDDEVELOPMENTSOFTWAREUSEDTODEVELOPANAPPLICATION,INSTALLATIONERRORS,SOFTWAREANDHARDWARECOMPATIBILITYPROBLEMS,MALFUNCTIONSORFAILURESOFELECTRONICMONITORINGORCONTROLDEVICES,TRANSIENTFAILURESOFELECTRONICSYSTEMS(HARDWAREAND/ORSOFTWARE),UNANTICIPATEDUSESORMISUSES,ORERRORSONTHEPARTOFTHEUSERORAPPLICATIONSDESIGNER(ADVERSEFACTORSSUCHASTHESEAREHEREAFTERCOLLECTIVELYTERMED"SYSTEMFAILURES").ANYAPPLICATIONWHEREASYSTEMFAILUREWOULDCREATEARISKOFHARMTOPROPERTYORPERSONS(INCLUDINGTHERISKOFBODILYINJURYANDDEATH)SHOULDNOTBERELIANTSOLELYUPONONEFORMOFELECTRONICSYSTEMDUETOTHERISKOFSYSTEMFAILURE.TOAVOIDDAMAGE,INJURY,ORDEATH,THEUSERORAPPLICATIONDESIGNERMUSTTAKEREASONABLYPRUDENTSTEPSTOPROTECTAGAINSTSYSTEMFAILURES,INCLUDINGBUTNOTLIMITEDTOBACK-UPORSHUTDOWNMECHANISMS.BECAUSEEACHEND-USERSYSTEMISCUSTOMIZEDANDDIFFERSFROMNATIONALINSTRUMENTS'TESTINGPLATFORMSANDBECAUSEAUSERORAPPLICATIONDESIGNERMAYUSENATIONALINSTRUMENTSPRODUCTSINCOMBINATIONWITHOTHERPRODUCTSINAMANNERNOTEVALUATEDORCONTEMPLATEDBYNATIONALINSTRUMENTS,THEUSEROR

APPLICATIONDESIGNERISULTIMATELYRESPONSIBLEFORVERIFYINGANDVALIDATINGTHESUITABILITYOFNATIONALINSTRUMENTSPRODUCTSWHENEVERNATIONALINSTRUMENTSPRODUCTSAREINCORPORATEDINASYSTEMORAPPLICATION,INCLUDING,WITHOUTLIMITATION,THEAPPROPRIATEDESIGN,PROCESSANDSAFETYLEVELOFSUCHSYSTEMORAPPLICATION.

TechnicalSupportandProfessionalServicesVisitthefollowingsectionsoftheNationalInstrumentsWebsiteatni.comfortechnicalsupportandprofessionalservices:

Support—Onlinetechnicalsupportresourcesatni.com/supportincludethefollowing:

Self-HelpResources—Foranswersandsolutions,visittheaward-winningNationalInstrumentsWebsiteforsoftwaredriversandupdates,asearchableKnowledgeBase,productmanuals,step-by-steptroubleshootingwizards,thousandsofexampleprograms,tutorials,applicationnotes,instrumentdrivers,andsoon.FreeTechnicalSupport—AllregisteredusersreceivefreeBasicService,whichincludesaccesstohundredsofApplicationsEngineersworldwideintheNIDiscussionForumsatni.com/forums.NationalInstrumentsApplicationsEngineersmakesureeveryquestionreceivesananswer.Forinformationaboutothertechnicalsupportoptionsinyourarea,visitni.com/servicesorcontactyourlocalofficeatni.com/contact.

TrainingandCertification—Visitni.com/trainingforself-pacedtraining,eLearningvirtualclassrooms,interactiveCDs,andCertificationprograminformation.Youalsocanregisterforinstructor-led,hands-oncoursesatlocationsaroundtheworld.SystemIntegration—Ifyouhavetimeconstraints,limitedin-housetechnicalresources,orotherprojectchallenges,NationalInstrumentsAlliancePartnermemberscanhelp.Tolearnmore,callyourlocalNIofficeorvisitni.com/alliance.

Ifyousearchedni.comandcouldnotfindtheanswersyouneed,contactyourlocalofficeorNIcorporateheadquarters.YoualsocanvisittheWorldwideOfficessectionofni.com/niglobaltoaccessthebranchofficeWebsites,whichprovideup-to-datecontactinformation,supportphonenumbers,emailaddresses,andcurrentevents.

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