Solving typical problems

You can check error messages with the errs serial line command. For a list of possible error messages, see Error codes. In case of constant error, contact Vaisala.

Table 1. Problems and solutions
Problem or message	Likely causes and solutions
Measurement not working, any of the following errors is active: Probe RH measurement error Probe T measurement error	Sensor(s) damaged or missing. Open the probe filter and check. Calibration is not done. Calibrate the probe. Check the supply voltage of the transmitter.
Transmitter cannot communicate with the probe, any of the following errors is active: Probe communication error Probe checksum error Probe message form error Measurements not available	Check the attachment of the probe to the transmitter. In case of remote probe, check also the interconnection cables. Replace the probe if necessary.
Serial line command not working, outputs Unknown command.	Mistyped or unknown command, check the command syntax and parameters.
Cannot connect to serial line, current serial settings of the module are unknown.	Perform the following steps to connect: Set your terminal settings to 19200 8 N 1 (the default settings of the transmitter). Connect to the service port of the transmitter. Power up the transmitter, and type "Z" on the serial line at least five times. The transmitter will come online with the default settings. Use the seri serial line command to set the desired serial settings and save the settings with the save command.
Any of the following errors is active: Current settings checksum error Default settings checksum error	Internal error. Perform the following steps: Reset or power cycle the module. Check if the error disappears. Return the module to factory settings with the frestore serial line command. Check again. If the error is still active, contact a Vaisala service center.
Any of the following errors is active: Program checksum error Factory flash defaults checksum error Factory flash not initialized Oscillator fault bit active	Faulty transmitter, contact a Vaisala service center.
Any of the following errors is active: Analog output quantity invalid ¹ Display quantity invalid	In case of Analog output quantity invalid error, select the correct output quantities (set with the calcs command) with the asel command. In case of Display quantity invalid error, select the correct display quantities with the dsel command.

¹ Measurement parameters are referred to as 'quantities' in the transmitter's software.

Solving typical problems - HMT120

HMT120 User Guide