4-20 Ma/Hart Output - Emerson Rosemount 644 Reference Manual

Reference Manual
00809-0200-4728
6.3 4–20 mA/HART output
6.3.1 Transmitter communication
Transmitter does not communicate with Field Communicator
Potential cause
Loop wiring
Recommended actions
6.3.2 High output
Potential cause
Sensor input failure or connection
Recommended actions
Potential cause
Loop wiring
Recommended actions
Check for dirty or defective terminals, interconnecting pins, or receptacles.
Potential cause
Power supply
Emerson.com/Rosemount
1. Check the revision level of the transmitter device descriptors (DDs) stored in
your communicator. The communicator should report Dev v4, DD v1
(improved), or reference
Emerson Customer Central for assistance.
2. Check for a minimum of 250 ohms resistance between the power supply and
Field Communicator connection.
3. Check for adequate voltage to the transmitter. If a Field Communicator is
connected and 250 ohms resistance is properly in the loop, then the
transmitter requires a minimum of 12.0 V at the terminals to operate (over
entire 3.5–23.0 mA operating range), and 12.5 V minimum to communicate
digitally.
4. Check for intermittent shorts, open circuits, and multiple grounds.
1. Connect a Field Communicator and enter the transmitter test mode to check
for a sensor failure.
2. Check for a sensor open or short circuit.
3. Check the process variable to see if it is out of range.
Field Communicator for previous versions. Contact
Troubleshooting
March 2021
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