Vaisala HMT120 - Manual (Page 13)

Chapter 2 ___________________________________________________________ Product Overview
VAISALA ________________________________________________________________________ 11
Constant Output Probe
The constant output probe HMP110REF is a testing accessory that can be
used to check the transmitter's functions and measurement signal transfer
chain all the way to the control system. The constant output probe does
not measure humidity and temperature; instead, it outputs constant
humidity and temperature readings.
The values output by the constant output probe are specified when
ordering. These values are written on an additional label on the probe
body.
The procedure for using the constant output probe is simply to replace
the original probe for the duration of the testing:
1. Disconnect the normal probe from transmitter.
2. Connect the constant output probe to the transmitter.
3. Check that all used outputs (analog, display, serial line) show the
correct measurement values.
4. After checking the outputs, disconnect the constant output probe
and reconnect the original probe.
NOTE The transmitter goes to the error state for a short time when the probe is
changed. This is normal.