Emerson Rosemount 644 Reference Manual page 104

Troubleshooting
March 2021
Sensor drift alert active
Sensor 1 is used here as an example. If Dual Sensors are ordered this alert can apply to
either sensor.
WARN DRIFT WARN ALERT
Potential cause
The difference between Sensor 1 and 2 has gone beyond the user-configured Drift Alert
Threshold.
Recommended actions
Sensor degraded
Sensor 1 is used here as an example. If Dual Sensors are ordered this alert can apply to
either sensor.
WARN SNSR 1 DEGRA SNSR 1
Potential cause
The resistance of the thermocouple loop has exceeded the configured threshold. This
could be caused by excess EMF.
Recommended actions
Calibration error
Potential cause
The value entered for the user trim point was not acceptable.
Recommended actions
Re-trim the device, ensure the user entered calibration points are close to the applied
calibration temperature.
104
1. Verify sensor connections are valid on the transmitter.
2. If necessary, check calibration of each sensor.
3. Verify process conditions match sensor outputs.
4. If calibration fails, one of the sensors has failed. Replace it at your earliest
convenience.
1. Check terminal connections on the terminal screws for corrosion.
2. Check the thermocouple loop for any signs of corrosion in terminal blocks, wire
thinning, wire breaks, or faulty connections.
3. Verify the integrity of the sensor itself. Harsh process conditions may cause
long-term sensor failures.
Reference Manual
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