Emerson Rosemount 644 Reference Manual page 100

Troubleshooting
March 2021
Recommended actions
Check the output voltage of the power supply at the transmitter terminals. It should
be 12.0–42.4 Vdc (over entire 3.75–23 mA operating range).
Potential cause
Electronics
Recommended actions
6.3.3 Erratic output
Potential cause
Loop wiring
Recommended actions
Potential cause
Electronics
Recommended actions
Connect a Field Communicator and enter the transmitter test mode to isolate module
failure.
6.3.4 Low or no output
Potential cause
Sensor element
Recommended actions
Potential cause
Loop wiring
100
1. Connect a Field Communicator and enter the transmitter status mode to
isolate module failure.
2. Connect a Field Communicator and check the sensor limits to ensure
calibration adjustments are within the sensor range.
1. Check for adequate voltage to the transmitter. It should be 12.0–42.4 Vdc at
the transmitter terminals (over entire 3.75–23 mA operating range).
2. Check for intermittent shorts, open circuits, and multiple grounds.
3. Connect a Field Communicator and enter the Loop test mode to generate
signals of 4 mA, 20 mA, and user-selected values.
1. Connect a Field Communicator and enter the transmitter test mode to isolate a
sensor failure.
2. Check the process variable to see if it is out of range.
Reference Manual
00809-0200-4728
Emerson.com/Rosemount