Instruction Manual

HMP230 SERIES
User's Guide M210225en-B
54
7.1.1. One point calibration procedure
The HMI38 humidity data processor or the HMI41 indicator can be used as a
one-point field calibrator. Two point calibration using the HMI38 is also
possible if two different humidity points (differing more than 50 %RH from
each other) can be provided. The HMI38 is connected to an HMP230
transmitter using an appropriate reference connection cable. The necessary
correction factors are automatically stored in the HMP230 memory. Detailed
calibration instructions are given in the HMI38 operating manual.
A one-point correction can also be done manually in the field against an accu-
rate reference.
NOTE
If the sensor has been changed, the calibration has to be
done according to the instructions in Chapter 7.1.3.
7.1.1.1. With serial commands
• Make sure that the sensors of the transmitter and the reference in-
strument are close to each other. Allow enough time for the sensor
heads to stabilize to the measurement conditions.
Disconnect the security lock jumper!
• Give command CRH <cr>, enter the humidity value and press <cr>.
>CRH <cr>
RH : xx.x Ref1 ? yy.y <cr>
Press any key when ready...
• If you want to see how the sensor stabilizes to the reference humidity
enter c <cr> instead of the first reference:
RH : 11.9 Ref1 ? c <cr>
RH : 11.5 Ref1 ? c <cr>
RH : 11.5 Ref1 ? 11.3 <cr>
Press any key when ready...
• Press any key and press <cr> when the transmitter requests the second
point value.
RH : yy.y Ref2 ? <cr>