Solving typical problems - GMW83 - GMW83A - GMW83D - GMW83DRP - GMW83DRPC - GMW83RPC - GMW84 - GMW84S - GMW86P

If you experience problems with GMW80 series transmitters, first see the following tables (for analog output and Modbus models) concerning the behavior and error indications of the transmitter. If you cannot locate the source of the error and return the transmitter to operational state, contact Vaisala. See Technical support.

Table 1. Troubleshooting table, transmitters with analog output
Problem or message	Possible cause	Solution
Analog output reading is unchanging and appears incorrect.	Transmitter has set the analog output to the error level (3.6 mA or 11 V) because the transmitter is in the error state.	Determine what has caused the error state and remove the cause. For a description of the error state and its possible causes, see Error state.
Temperature reading is too high.	Transmitter is installed in an unsuitable location, for example, near a heat source or in sunlight.	Relocate transmitter. See Selecting location.
	Transmitter is installed in improper orientation.	Reinstall transmitter with the arrow on the mounting base pointing up.
	Unsuitable operating environment.	Verify that the operating environment is within specified operating limits.
CO₂ reading is too high.	Source of CO₂ near the transmitter.	Use a portable instrument to verify the CO₂ reading at the installation location. Avoid breathing on the instruments while checking. Check for sources of CO₂ in the measured area, such as people working right next to the transmitter.
CO₂ reading is too high.	CO₂ measurement module must be replaced.	See Replacing the CO2 measurement module (GM10).
CO₂ reading is too low.	The measured area contains materials that bind CO₂ (such as fresh concrete), producing a low-CO₂ environment.	Use a portable instrument to verify the CO₂ reading at the installation location. Avoid breathing on the instruments while checking. Check if the transmitter is installed on a mounting box that supplies air from inside the wall into the transmitter. If yes, seal the opening that supplies the air.
CO₂ reading is too low.	CO₂ measurement module must be replaced.	See Replacing the CO2 measurement module (GM10).
Relay is always activated.	Relay setpoint set too low.	Adjust the relay setpoint. See Relay.
Error text on display: CO2-SENSOR	GM10 module disconnected.	Open the transmitter and check if the GM10 module is installed securely. See Figure 2. If the module is loose or entirely disconnected, reinstall it as instructed in Replacing the CO2 measurement module (GM10). If the GM10 module appears to be installed but the problem persists, disconnect and reconnect the module carefully.
	CO₂ measurement module must be replaced.	Replace the GM10 module with a verified working module.
	CO₂ reading over 6000 ppm.	Use a portable instrument to verify the CO₂ reading at the installation location. Avoid breathing on the instruments while checking. Check for sources of CO₂ in the measured area, such as people working right next to the transmitter.
Error text on display: RH-SENSOR	Humidity sensor disconnected.	Open the transmitter and check the condition of the humidity sensor. See Figure 2. If the sensor is missing or damaged, replace it. See Replacing the INTERCAP humidity sensor. If the sensor is wet, wait for it to dry or dry it very gently with clean instrument air.
	Humidity sensor damaged.
	Humidity sensor wet.
Error text on display: T-SENSOR	Temperature reading is outside the scaled output range.	Verify the ambient temperature with a portable instrument. See Analog output overrange behavior.
Error text on display: T-SENSOR	Temperature sensor damaged.	Open the transmitter and check if the active temperature sensor on the component board has been damaged. See Figure 2.
Error text on display: INTERNAL	Problem with transmitter software.	Restart the transmitter. If the error persists, contact Vaisala support.

Table 2. Troubleshooting table, transmitter model GMW87
Problem	Solution
The device is not responding	Power-cycle the transmitter by disconnecting the screw terminal block Check power supply voltage Check wiring, including RS-485 bus polarity Check that RS GND is connected between the transmitter and the receiver Compare the DIP switch settings to your Modbus host settings Check that RS-485 termination is enabled only on the last device of the wiring Alternatively, try operation without RS-485 termination at all
Unexpected value in Modbus response	Change register number and/or data encoding settings in your Modbus host system
No measurement result and/or non-zero status code returned	Device is warming up, try again after 20 seconds Power-cycle the transmitter by disconnecting the screw terminal block Check that the GM10 module is properly attached Contact Vaisala for a replacement GM10 module

Solving typical problems - GMW83 - GMW83A - GMW83D - GMW83DRP - GMW83DRPC - GMW83RPC - GMW84 - GMW84S - GMW86P - GMW87M

GMW80 Series User Guide