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TechnicalInformation
Guidelines for Layout and Installation of Field Wireless Devices
TI 01W01A51-12EN
TI 01W01A51-12EN©Copyright Aug. 2013 (KP)1st Edition, Aug. 2013 (KP)
Yokogawa Electric Corporation2-9-32, Nakacho, Musashino-shi, Tokyo, 180-8750 JapanTel.: 81-422-52-5634 Fax.: 81-422-52-9802
ContentsIntroduction ......................................................................................................2Revision Information .......................................................................................3Terms and definitions .....................................................................................4Overview ...........................................................................................................5Part A. Layout and Topology of Wireless Devices ....................................6
A1. Star topology ...................................................................................................6 A2. Mesh topology .................................................................................................7
Part B. Guidelines for Device Layout and Installation ..............................8B1. Communication distance .......................................................................................8
B1.1 Classificationofcommunicationenvironmentandexpected communicationdistance ........................................................................8
B2. Installation procedure ..........................................................................................10B2.1 Selecting the star topology ..................................................................10B2.2 Selectingthemeshtopology ...............................................................11B2.3 Configuringthemeshtopologywiththreeormorehops ....................12B2.4 Other installation procedures: using high-gain antennas ....................13B2.5 Other installation procedures: using extension antenna cables .........14
B3. Using routers .........................................................................................................15B3.1 Installingrouterssothatalltransmittershavetwocommunicationpaths ..15B3.2 Installing routers as high as possible ...................................................15B3.3 Using a 2 dBi antenna for routers ........................................................15B3.4 Examplesofrouterinstallation ............................................................16
Part C. Guidelines for Implementing the Site Survey .............................17C1. Installation design with a site plan/device layout only (visual assessment and site survey are not required) .....................................17C2. Installation design with a site plan/device layout and visual assessment (site survey is not required) .................................................................................17C3. Installation design requiring a site survey ........................................................17
Part D. Examples of Installation Design Not Requiring Site Surveys ...19D1. Installation guidelines are followed ....................................................................19D2. Devices are mounted on rotating objects ..........................................................19D3. Devices are installed in a small space (50 m square or smaller) ....................20
Part E. Examples Clearly Requiring Site Surveys...................................21E1. Installation in a place surrounded by metal walls .............................................21E2. Wi-Fi communication close to the field wireless system .................................22
Reference 1: Fresnel Zone .....................................................................................................23Reference 2: Requirements for Antenna Installation ..........................................................25Reference 3: Packet Error Rate (PER) ..................................................................................26
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Introduction
IntroductionThisguidelineexplainshowtoinstallfieldwirelessdevicesinasystemwiththeYFGW410fieldwirelessmanage-mentstationandYFGW510fieldwirelessaccesspoint,andhowtodeterminewhetheractualcommunicationtestsareneeded.Layoutexamplesthatcomplywiththeguidelinesarealsoshown.
Thefollowingsymbolsareusedintheproductanduser’smanualtoindicatesafetyprecautions:
CAUTIONThissymbolindicatescautionsrequiredwhenhandlingtheproduct.Thissymbolisplacedonpartsoftheprod-uctrequiringreferencetotheuser’smanualtoprotecttheoperatorandtheproductitself.Intheuser’smanual,thissymbolisaccompaniedbyprecautionstoavoidphysicalinjuryordeathoftheoperator,includingelectricalshocks,injury,andothers.
WARNINGThissymbolindicatesinstructionsthatmustbeobservedtopreventthesoftwareorhardwarefrombeingdam-agedorthesystemfrombecomingfaulty.
IMPORTANTThissymbolindicatesimportantinformationrequiredtounderstandoperationsorfunctions.
All Rights Reserved. Copyright © 2013, Yokogawa Electric Corporation
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Revision Information
Revision InformationTitle: Guideline for layout and installation of field wireless devices
Manual No.: TI 01W01A51-12EN
Edition Date Page Revised Item1st August 2013 New Issue
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Terms and definitions
Terms and definitionsl Visual assessmentAvisualassessmentinvolvesvisuallyevaluatingthesitetochecktheline-of-sightofwirelesscommunicationpaths,howtoinstallwirelesstransmitters,howtofeedpowertoaccesspoints,andhowtolayoutthecommunica-tionpathstotheuppersystem.
l Site surveyAsitesurveyisanactualcommunicationtestwithequipmentatproposedinstallationpointstocheckthereliabilityofwirelesscommunicationpaths.
l Access point (AP)Inthisdocument,theYFGW510fieldwirelessaccesspointisreferredtoasanaccesspoint(AP).
l Router (RT)Inthisdocument,adevicethatrelayswirelesscommunicationisreferredtoasarouter(RT).
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Overview
OverviewYokogawa’sfieldwirelesssystemconformingtotheISA100.11astandardfeaturesalongcommunicationdis-tancewithlowerrorrateandhighreceiversensitivity.Thesystemisdesignedforcustomerswhorequirereliabil-ity,performance,andfutureinnovation.Tomakefulluseoffieldwirelessdevices,theoptimalinstallationlayoutisrequired.
Althoughconditionsatinstallationsitesdifferfromplacetoplace,astudyofthesiteplan/devicelayoutorvisualassessmentisusuallyenoughtoensureasuccessfulinstallation.Theseassessmentsassureefficientnetworkdesignandreliablecommunications.However,anactualcommunicationtestisrecommendedtoconfirmthereli-abilityofcommunicationpathsandtofindtheoptimumlayoutinharshenvironmentsforwirelesssignals.
Communicationdistanceisakeyindicatoroftheperformanceofwirelessdevices.Wirelessdeviceswithlongercommunicationdistanceusuallyhavehigherperformance.Wirelesscommunicationdistanceisevaluatedwiththepacketerrorrate(PER).Underidealcircumstances,thePERcorrelatesdirectlywiththereceivingsignalstrengthindicator(RSSI),andthusthePERcanbepredictedfromthevalueofRSSI.However,RSSIcorrelatespoorlywithPERinaplacesurroundedbymetalstructuresbecauseofmultipathfadingandobstacles.Therefore,YokogawadirectlyusesthePERasanevaluationparameter.
Thefieldwirelesssystemre-sendspacketswhenwirelesscommunicationfails.IfthePERishigh,thesystemrepeatedlysendslostpackets,whichdelaysthedatafromwirelesstransmittersreachingtheuppersystem.Inaddition,wirelesssignalsareoftenreflectedoffmanymetalstructuresinaplant,causingthePERtobecomeunstable,andthedegreeofdelaytofluctuate.Withalongdelay,thesystemmaynotsatisfyrequireddataupdatecycles.Inparticular,thedelaybecomesworseinasystemwithahighPERinameshtopologywhichusesrout-ers (see Part B).
LayingoutfieldwirelessdevicesasdescribedinthisdocumentwillhelpsuppresstheincreaseinPEReveninharshenvironments,andstabilizewirelesscommunication.
PartAexplainsthebasicwirelessconnectiontopology.PartBdescribeshowtoinstallfieldwirelessdevices.PartCshowstheevaluationprocedureinsitesurveys,andPartDandEshowexamplesofjudgingthenecessityofsite surveys.
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Part A. Layout and Topology of Wireless Devices
Part A. Layout and Topology of Wireless Devices
Toenablewidespreadusage,Yokogawa’sfieldwirelesssystemsupportstwonetworktopologies:startopologyandmeshtopology.
Thetopologyandlayoutarecloselyrelated.Thestartopologyisusedwhenthesamplingintervalislessthan5seconds.Themeshtopologyisusedforasamplingintervalof5secondsorlongerbecausetransmissionmaybedelayedduetothemulti-hopconfiguration.
Basically, devices are laid out as follows:
A1. Star topologyInthestartopology,anaccesspointcommunicateswithmultiplewirelesstransmittersdirectly.Therefore,thesedevicesortheirantennasmustbeinstalledtosecuretheline-of-sightandFresnelzone(seeReference2).InClass A and B areas (see Section B1.1), it is crucial to secure the line-of-sight.
InClassCareas,ontheotherhand,theline-of-sightmaynotmatterbecauseoftheshortwirelesscommunica-tiondistance.Themaximumcommunicationdistancecanbeextendedbyavoidingobstacleswithremoteanten-nas or by using high-gain antennas.
Figure A-1 Star topology
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Part A. Layout and Topology of Wireless Devices
A2. Mesh topologyYokogawa’sfieldwirelessnetworksupportsuptofourhopsforthemeshtopology.Themeshtopologyassuresscalabilityandconnectivitybyinstallingrouterssufficientlyhightogiveaclearline-of-sight.Themeshtopologyisused for securing redundancy or avoiding obstacles.
Asageneralrule,Yokogawa’sfieldwirelessdevicesareinstalledwithintwohopsasshowninFigureA-2.Rout-ersareinstalledhighupovertheplant.YokogawacallsthisformSkyMesh.Notethatifthenumberofhopsincreases,thedevicelayoutandinstallationdesignwillbecomecomplicated,whichlimitsthenumberofdevicesthatcanbeconnectedtotherouters.Athree-orfour-hopconfigurationshouldbeusedonlywherecommunica-tion devices are arranged in a line such as off-site of wellheads.
RoutersortheirantennasareinstalledatheightstosecuretheFresnelzonedependingonthecommunicationdistancebetweenroutersandanaccesspoint(describedlater).Thiscanreducetheinfluenceofobstaclessuchasfixedfacilitiesanddevices,aswellastheeffectofmovingobstaclessuchaslargevehiclesorcranetrucks.
(a) Sky Mesh in a plant
(b) Mesh topology for a redundant path network
Figure A-2 Mesh topology
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Part B. Guidelines for Device Layout and Installation
Part B. Guidelines for Device Layout and Installation
Therearethreeguidelinesforthelayoutoffieldwirelessdevices:communicationdistance,installationprocedure,and use of routers.
B1. Communication distanceYokogawa’sfieldwirelessdevicesconformingtotheISA100.11astandardfeaturealongcommunicationdis-tance.ThedatainthissectionarebasedonYokogawa’sfieldwirelessdevicesonly.
B1.1 Classification of communication environment and expected communication distance
Tofacilitatethelayoutandinstallationoffieldwirelessdevices,Yokogawaclassifiestheexpectedcommunicationdistanceintothreeclassesaccordingtothecommunicationenvironment.Theexpectedcommunicationdistanceismeasuredwitha2dBiantennawithallinstallationrequirementssatisfied(includingthegainofanantennawithoutputof10mW).
1. Free space (Class A): Area with no obstacles around wireless devicesExpectedcommunicationdistance:upto500m
Examples:Pipeline,tankyard
Figure B-1 Example of Class A area
2. Minor obstacles (Class B): Area with structures and obstacles which affect wireless signals through reflection, etc.Expectedcommunicationdistance:upto200m
Examples:Areaswithbuildingsormachinesaroundthecommunicationpath.Areaswithdensepipingalongthecommunicationpath.
Figure B-2 Example of Class B area
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Part B. Guidelines for Device Layout and Installation
3. Dense obstacles (Class C): Area surrounded by structures and obstacles which severely affect wireless signals.Expectedcommunicationdistance:upto50m
Examplesofarea:Insideoftheplantsurroundedbypipesandmachines
Figure B-3 Example of Class C area
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Part B. Guidelines for Device Layout and Installation
B2. Installation procedureThis section outlines the usage criteria for routers, high-gain antennas, and extension antenna cables. There are two general rules about the installation regardless of whether or not to use these devices.
l Up to two hopsAsthenumberofhopsincreases,thenumberoftransmittersconnectabletoeachrouterdecreases,whichmakesitdifficulttolayoutthesystem.
l Installation at heightsAntennasshouldbeinstalledatheightstoavoidtheinfluenceofbothfixedobstacles(buildings,etc.)andmov-ing obstacles (vehicles, etc.) in a plant.
Selectanappropriateinstallationproceduredependingontherequirementsbelow:
Communication cycle of less than 5 seconds Star topology
Mesh topologySky MeshAvoid obstacles/Extend distance
Mesh topology with three or more hopsLong-distance communication with multi-hops
Use of remote antennas
Use of high-gain antennas
Other installation procedure:Avoid small obstaclesLong-distance communication with one hop
Figure B-4 Selection of an installation procedure
B2.1 Selecting the star topologyWhenacommunicationcycleoflessthan5secondsisrequired,thestartopologyisrecommendedtobeusedforcommunicationbetweentransmittersandanaccesspoint.Evenwhenthereareobstaclesintheline-of-sight,thestartopologyensurescommunicationaslongasthecommunicationdistanceis50morshorter.Thisisbecausewirelessdevicescanreceivesignalswhicharereflectedoffthesurroundingpipingorwalls.
Figure B-5 Selecting the star topology
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Part B. Guidelines for Device Layout and Installation
B2.2 Selecting the mesh topologyl Sky Mesh in a plantAsdescribedearlier,routersatheightswithaclearline-of-sightimproveexpandabilityandconnectivity.De-vicesinstalledasshowninFigureB-6(a)coverawideareaofcommunication.Whenroutersareinstalledsoastooverlapeachother’scommunicationareaasshowninFigureB-6(b),communicationismaintainedevenifthemeasuringpointsmovewithinaspecifiedareasuchascoalstorageyards.
(a) Sky Mesh configuration
(b) Coal storage yard
Figure B-6 Example of the mesh topology
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Part B. Guidelines for Device Layout and Installation
l Avoiding obstacles and extending the communication distanceInstallingroutersinthemeshtopologyextendscommunicationbeyondtheexpectedcommunicationdistancewhile avoiding obstacles*1.RoutersandtheirantennasareinstalledsothattheFresnelzoneissecured.Use2-dBi standard antennas in consideration of their directivity angle*2. For details on installing routers, see the following section.
Figure B-7 Avoiding obstacles with the mesh topology
*1:Relativelysmallobstaclescanbeavoidedbyshiftingantennaswithextensionantennacables(upto13m)describedlater.*2: For details of the directivity angle, see Reference 2.
B2.3 Configuring the mesh topology with three or more hops
Themeshtopologyisbasicallyconstructedwithuptotwohops,butitcanbeconstructedwiththreeorfourhopswherelong-distancecommunicationisrequiredsuchaswellheadsandoffshoreplantsaslongasrouterscanbeinstalledinaline.Inthiscase,thenumberofdevicesconnectabletoroutersdecreases.Fordetails,see“G2.6.1RestrictionsontheNumberofConnectableDevicesbyNetworkResources”(IM01W02D01-01EN).
Figure B-8 Example of the mesh topology at a wellhead
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Part B. Guidelines for Device Layout and Installation
B2.4 Other installation procedures: using high-gain antennas
Withahigh-gainantenna,longercommunicationthantheexpectedcommunicationdistanceispossible.Inthiscase,theheightoftheantennaandtheFresnelzonemustbeconsideredasshowninReference1.Becausehigh-gain antennas need a clear line-of-sight, they are not used in Class B and C areas.
l Order of priority when installing high-gain antennasIfthedistancebetweenwirelessdevicesexceedsthemaximumcommunicationdistanceintherelevantclass,useahigh-gainantennaforaccesspoints.Inthiscase,sufficientheightisnecessarytosecuretheFresnelzone.Fordetails,seeReference1.
l Antenna height of the target deviceWhenahigh-gainantennaisused,theantennaheightofthetargetdevicemustbeconsidered.Theantennaofthetargetdevicemustbewithintheradiationangleofthehigh-gainantenna.
Table B-3 shows the allowance of the antenna position of the target device (difference in height between the originating antenna and the destination antenna) when using a 6 dBi antenna as the originating antenna. In this case,theallowanceisaboutone-fifththecommunicationdistance.
Communication distance
Allowable difference in heights
Figure B-10 Relationship between the communication distance and antenna height
Table B-3 Correlation between communication distance and allowable antenna height
Communication distance (m)
Allowable antenna height [m]
10 2
50 10
100 20
200 40
500 100
800 156
*Notethatthereisnoneedtoconsidertheallowableantennaheightinlong-distancecommunication.Foracommunicationdistanceof100morlonger,adifferencebetweenantennaheightsof20mormoreisallowable.Thisguidelineappliestocaseswhereantennaheightsareextremelydifferentfromeachother..
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Part B. Guidelines for Device Layout and Installation
B2.5 Other installation procedures: using extension antenna cables
Tosetupcommunicationfrominsideabuildingtotheoutsideortoavoidsmallobstacles,usea3mor13mextension antenna cable. Extension cables are often a useful way to secure an excellent line-of-sight.
(a) Installing an antenna outside the building (b) Securing the Fresnel zone
Figure B-11 Using an extension antenna cable
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Part B. Guidelines for Device Layout and Installation
B3. Using routersFollow the guidelines below when installing routers.
l Installingrouterssothatalltransmittershavetwocommunicationpaths.
l Install routers as high as possible.
l Usea2dBiantennaforrouterswhichcoverI/Odeviceslocatedbelow.
B3.1 Installing routers so that all transmitters have two communication paths
Ifthereisonlyonecommunicationpathandtherouterbatteryneedstobechangedoracommunicationfailurehappens,thedatafromtransmitterswillbelost.Installingrouterstosecureatleasttwocommunicationpathscansignificantlyreducetheriskofdataloss.
B3.2 Installing routers as high as possibleTosecurecommunicationqualitybetweentherouterandanaccesspoint,installroutersashighaspossiblewithaclearline-of-sighttotheaccesspoint.Thisminimizesdisturbancescausedbyvehiclesandhumansandmakescommunicationmorereliable.
B3.3 Using a 2 dBi antenna for routersUsea2dBiantennaforrouterswhichcoverI/Odeviceslocatedbelow.Thisisbecause2dBiantennashaveawidedirectivityangleandareidealforverticalcommunication(seeReference2).Withagoodline-of-sight,2dBiantennascancommunicatewiththetargetdeviceoveradistanceofupto30mevenifitislocatedoutoftheradiation angle.
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Part B. Guidelines for Device Layout and Installation
B3.4 Examples of router installationInstallrouterssothatareliablecommunicationpathwithfewobstaclesissecured.
(1) Secure a communication path above obstacles between the access point and the router.
Figure B-12
(2) Secure vertical communication paths among the router and transmitters.
Figure B-13
(3) A poor line-of-sight does not affect communication between the router and transmitters as long as the communication distance is 50 m or shorter.
Figure B-14
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Part C. Guidelines for Device Layout and Installation
Part C. Guidelines for Implementing the Site Survey
Thissectionandthefollowingsectionsdescribethetypesofdevicelayout.Alayoutwithvisualassessmentaloneand another one which needs a site survey are illustrated.
Visualassessmentisnecessaryforconfirminghowtomounttransmitters,howtofeedpowertotheaccesspoint,andhowtoconnecttheuppersystem,andisalmostthesameasthatforwiredtransmitters.Whendesigningafieldwirelessnetwork,thefollowingadditionalinformationisneeded:asitemap,layoutofotherdevices,andad-ditionalinformationtojudgeapplicabilitytothedesigntypesdescribedbelow.
If the feasibility of installation is still not clear, carry out a site survey.
C1. Installation design with a site plan/device layout only (visual assessment and site survey are not required)
Thisdesignisapplicablewhenthefollowingconditionsareconfirmedwiththesiteplan:
Outdoorinstallation,topologywithuptotwohops,goodline-of-sight,andsufficientheightofantennassecuringtheFresnelzonewithnoobstacles
C2. Installation design with a site plan/device layout and visual assessment (site survey is not required)
Whenthedesignfollowstheinstallationguidelinesandtherearenoother2.4GHznetworks(e.g.,Wi-Fi),sitesurveyscanbeomitted.
Thefollowingtwocasesdonotrequireasitesurvey:
1.Wirelessdevicesarefixedinaroomwithanareaof50msquareorsmaller.Wirelessdevicescanbemountedonrotatingobjectsbutnotonmovingobjects.
2.Wirelessdevicesaremountedinaspacewithametalgratingfloor,butthecommunicationdistanceis50morshorter.
C3. Installation design requiring a site surveyIfthefeasibilityofinstallationisstillnotclearafterthevisualassessmentandinstallationdesign,carryoutasitesurvey.
The following cases clearly need site surveys:
1.Communicationbetweenindoorsandoutdoors.Atleastonewirelessdeviceislocatedinashieldedenclosuresuchasabasementorprefabricatedbuilding.
2.Wirelessdevicesaremountedonmovingobjects.
3.Thereisanother2.4GHznetwork(e.g.,Wi-Fi)nearthecommunicationpath.
4.Therearenoisesourcesnearthecommunicationpath(e.g.,militarycommunicationfacilitiesandradarswithhigh output power).
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Part C. Guidelines for Device Layout and Installation
START
A site survey is required.
Visual assessment
Installation design
Another 2.4 GHz wireless communication exists.
All installation guidelines are followed.
END
Yes
No
No
Yes
No
Yes
Yes
Yes
No
Falls in any of the cases in C3.
Falls in either of the two cases in C2.
Figure C-1 Flow chart for judging the necessity of site surveys
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Part D. Examples of Installation Design without Site Survey
Part D. Examples of Installation Design Not Requiring Site Surveys
D1. Installation guidelines are followed
Figure D-1 Example of a layout following the guidelines
D2. Devices are mounted on rotating objectsTheline-of-sightfromtransmittersmountedonrotatingobjectstoanaccesspointisperiodicallydisturbedbytheobjects.However,communicationcancontinuethankstoreflectedsignals.Theareaoftheinstallationsite,mate-rialofthewalls,andotherpossibleobstaclesatthesitemustbesurveyed.
Figure D-2 Example of mounting on a rotating object (1)
Figure D-3 Example of mounting on a rotating object (2)
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Part D. Examples of Installation Design without Site Survey
D3. Devices are installed in a small space (50 m square or smaller)
Evenwithapoorline-of-sightorobstaclesincludingmetalgratingfloors,transmitterscanmaintaincommunica-tionaslongasthecommunicationdistanceis50morshorter.
Well
5 m
20 m
I/O
AP
AP
15 m
Metal grating floor
Cimney pipe
15 m
AisleI/O
I/O
Figure D-4 Example of installation with obstacles and metal grating floors
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Part E. Examples Which Clearly Require Site Survey
Part E. Examples Clearly Requiring Site Surveys
E1. Installation in a place surrounded by metal walls
Asitesurveyisrequiredbeforeinstallingtransmittersinaplacesurroundedbymetalwalls.Possibleroutesofcommunicationshouldbeexploredinthesitesurveybecausewirelesssignalscannotpassthroughmetalwalls.Wirelesssignalscancommunicatethroughnon-metalwalls,althoughthesignalswillbeattenuatedtosomeextent.
Figure E-1 Space surrounded by metal or concrete walls
Figure E-2 A transmitter surrounded by metal walls
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Part E. Examples Clearly Requiring Site Surveys
Figure E-3 A transmitter surrounded by concrete walls
(a) Installation in a pipe rack (b) Installation in a tunnel
Figure E-4 Small installation area in which it is difficult to secure the Fresnel zone
E2. Wi-Fi communication close to the field wireless system
PleasecontactthenearestYokogawasalesofficeorYokogawarepresentative.
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Referense
Reference 1: Fresnel ZoneForreliablewirelesscommunication,itisimportantnotonlytosecuretheline-of-sightbutalsotoensurethattherearenoobstaclesinthesurroundingspace.ThisspaceiscalledtheFresnelzoneandislargestatthemid-pointofthecommunicationdistance.TheradiusoftheFresnelzonedependsonthecommunicationdistance.
The largest radius of the Fresnel zone
I/O or RT
The largest radius of the Fresnel zone
(m)Distance
(m)
Ifthereareanyobstacleswithinthezone,thecommunicationdistancebecomesshorter.Thegroundisalsoapossible obstacle. Therefore, when installing wireless devices, the effect of the ground can be expected even if therearenoobstaclesbetweenthem.Referringtothetableabove,wirelessdevicesmustbemountedhigherthanthelargestradiusoftheFresnelzone.
Maximum communication distance with an intact Fresnel zoneInordertoestimateacommunicationdistanceforeachpath,theexpectedcommunicationdistanceinrespectiveenvironmentalclassifications(A,B,C)andobstaclesintheFresnelzone(seeReference1)mustbeconsidered.Thetablebelowshowstheexpectedcommunicationdistanceinconsiderationofthefactors.
Table Communication distance depending on factors
Combination of antennas
Antenna height (m)
Maximum communication distanceClass A (500 m) Class B (200 m) Class C (50 m)
2 dBi - 2 dBi
4.0 500 250
503.1 300 150
1.8 100 50
0.5 ----- 50
2 dBi - 6 dBi
5.5 1000 ----- -----
5.0 800 ----- -----
4.5 600 ----- -----
6 dBi - 6 dBi
7.5 1500 ----- -----
6.5 1250 ----- -----
5.5 1000 ----- -----
Evenifaline-of-sightcannotbesecured,goodcommunicationisexpectedinaClassCareaaslongassignalscanreflectoffsurroundingstructures(unlessthewirelessdevicesareenclosedbymetalwalls).Fordetails,seeB2.
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Referense
Figure Antenna height necessary for 500 m and 1000 m communication
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Referense
Reference 2: Requirements for Antenna InstallationTosatisfythecommunicationdistancespecification,antennasmustbeinstalledincompliancewiththefollowingconditions.Otherwise,communicationdistancesmaybecomeshorter.
A.Fieldwirelessdevicesmustbemountedwherenoobstaclesexistneartheirantenna.
B.Antennasmustbeinstalledvertically.
C.Antennasmustbeatleast30cm*awayfrommountingpipingorplumbing.
D.Iftheinstallationlocationistooclosetowalls,usearemoteantennaandextensionantennacabletopreventobstaclesfromaffectingwirelesssignals.
E.InClassAandBareas,installfieldwirelessdevicessothateachhasagoodline-of-sighttootherantennasinthecommunicationarea.Usearemoteantennaandextensionantennacable,ifnecessary.Thisisnotes-sentialinaClassCareabecauseitisdifficulttosecureagoodline-of-sightonlywithextensionantennacablesin such an area.
F.Whendevicesareinstalledatdifferentheights,overlaptheircommunicationrangesinconsiderationofthera-diationcharacteristicsofrespectiveantennas.Thus,forexample,standard2dBiantennascanemitsignalsupto45degreesupordownfromthehorizontalplane.Meanwhile,6dBiantennasemitonlywithin±11degrees.So,6dBiantennasarenotappropriateforverticalcommunication.
*When 2 dBi antennas are used in a Class C area(When2dBiantennasareusedinClassAorBareas,antennasmustbeatleast1mawayfrommountingpipingorplumbing.)
Radio propagation area(standard antenna)
L max
Vertical range
Antenna
45°
45°
Horizontal range1.5 m or
higher
30 cm or more
Requirements for mounting
2B piping mounting
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Referense
Reference 3: Packet Error Rate (PER)Thepacketerrorrate(PER)isagoodindicatortojudgethereliabilityofcommunicationpaths.ThePERequationis as follows:
PER(%)=Numberoflostpackets/Numberoftransmittedpackets×100
Packetsareconsideredaslostwhenan“acknowledge”packetfromthetargetdeviceisnotreceivedorwhena“noacknowledge”packetfromthetargetdeviceisreceived.
Yokogawa’sfieldwirelesssystemre-sendspacketswhenitdetectspacketloss.WithalowPER,devicescansuccessfully send all data with fewer retries.