Vaisala HMP240 - Manual (Page 75)

HMP240
M210300en Appendix 1: Serial commands
73
2. CALIBRATION COMMANDS
CRH Relative humidity calibration
Disconnect the security lock jumper!
CRH <cr>
With this command the transmitter can be calibrated against a reference. A
one-point calibration can be done against an accurate transfer standard in the
field and a two-point calibration using saturated salt solutions in controlled
conditions. A two-point calibration is performed as follows:
>CRH <cr>
RH : 12.00 Ref1 ? 11.3 <cr>
Press any key when ready ...
RH : 76.00 Ref2 ? 75.5 <cr>
In one-point offset correction, the Ref2 prompt is acknowledged with <cr>:
>CRH <cr>
RH : 12.80 Ref1 ? 11.3 <cr>
Press any key when ready ...
RH : 75.50 Ref2 ? <cr>
If the stabilization of the sensor to the humidity in the calibrator needs to be
monitored, the measurement output can be repeated by giving command c<cr>
at Ref1 and Ref2:
>CRH <cr>
RH : 12.00
Ref1 ? c <cr>
RH : 11.70 Ref1 ? c <cr>
RH : 11.50 Ref1 ? 11.3 <cr>
Press any key when ready ...
RH : 76.00
Ref2 ? 75.5 <cr>
FCRH Relative humidity calibration after sensor change
Disconnect the security lock jumper!
FCRH <cr>
After humidity sensor change the transmitter must be calibrated using this
command and the calibration must be done at two reference points. The cali-
bration is performed as follows:
>FCRH <cr>
RH : 1.90
Ref1 ? 11.3 <cr>
Press any key when ready ...
RH : 76.30 Ref2 ?
74.9 <cr>