calibrating and trimming instruments via hart
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Calibrating and Trimming Instruments via HARTAgenda:
What is HART? / History / Signal / Message Frame HART Command Structure
Connecting a HART Transmitter Trimming Devices Trimming Conventional Transmitter vs. HART Transmitter Live Demo
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What is HART?HART = Highway Addressable Remote Transducer
A digital communication protocol designed for industrial processmeasurement applications.
Uses a low-level modulation (FSK) superimposed on the standard4 to 20 mA current
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HART HistoryRevision Year
2.0 19873.0 19884.0 19895.x 1989 still
delivered today6.0 2001
never introduced7.0 2007
introduction of HART wireless
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HART Signal
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HART Message Frame
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HART Command StructureThree levels of commands Universal commands Common practise commands Device Specific commands
Universal commandsModel IDTag IDDescriptionMessageDateRange ValuesInstrument LimitsProcess MeasurementsDevice Status
Common practice commandsRead VariablesCalibration (zero, span)Initiate Self TestsSerial NumberTime Constant Values
Device Specific commandsModel Specific FunctionsStart, Stop, or Clear TotalizerSelect Primary VariableSpecial Calibration OptionsPID - SP, Tuning, Etc.
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Connecting a HART TransmitterPoint-to-point
24V supply
+
_
ResistorTransmitter
HARTCommunicator
mA
mA
Polling address = 0 !=> HART + mA signal
HART
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Connecting a HART transmitterMultidrop
24V supply
+
_
Resistor
Transmitters (max 15 pcs), fixed 4 mA current,Only PV output, different addresses (not 0 !)
HARTCommunicator
4 mA(fixed)
...
Addr=1 2 15
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Trimming Devices
Communicators Smart Calibrators
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MC5 Internal Connections
24V supply
+
_
ResistorTransmitter
HARTCommunicator
mA
mA
MC5
+24V
Ground
HART
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HART vs. Conventional Transmitter (1of 2)
Conventional transmitter
Input 4 20 mA
Adjustments: Zero Span
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HART vs. Conventional Transmitter (2 of 2)
HART transmitter
Input 4 .. 20 mA
Digital trim Analog trim
RangeTransferFunction
PV
PV
Input section Output sectionConversion
AO
AO
A/D D/A
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Live Demo
Presented by:Ned Espy Consulting Director
Beamex, Inc.Office: 770-951-1927Mobile: 404-386-8158ned.espy@beamex.com www.beamex.com
mailto:ned.espy@beamex.comhttp://www.beamex.com/http://www.beamex.com/mailto:ned.espy@beamex.com
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