Problem situations - GMP251

GMP251 User Guide

Document code
Document type
User guide
Problem Possible cause Remedy
Analog output reading is unchanging and appears incorrect. Analog output is in error state. Remove the cause of the error state and the analog output will recover its normal function.
Probe outputs stars "****" on serial line instead of measurement data. Incorrect supply voltage. Check the power supply.

Check the active errors using the ERRS command on the serial line.

Unsuitable operating environment. Verify that the operating environment is within specified operating limits.
Unable to access probe on the RS-485 line. Incorrect wiring. Check that the RS-485 connection is wired correctly.
Probe in POLL mode with unknown address. Power cycle or reset the probe and try again.
CO2 measurement not working. Condensation on the sensor. Remove the filter and check if condensation has formed on the sensor. If yes, dry out the condensation with instrument air and insert a new dry filter. Keep the probe powered and operating to prevent re-occurrence.