Vaisala HMT330 - Manual (Page 164)

User's Guide _______________________________________________________________________
162 __________________________________________________________________ M210566EN-K
Example Multipoint Adjustment Procedure
1. Connect the HMT330 to a PC. See section Serial Line
Communication on page 79. Open a terminal program.
2. Issue the PURGE command to carry out the chemical purge, and
wait for six minutes for it to complete. Transmitters without the
chemical purge feature will not respond to the command.
>purge
Purge started, press any key to abort...
3. Press the ADJ button on the component board.
4. View the currently applied standard user adjustment offset and gain
using the L command. If offset is zero and gain is one (example
shown below), no user correction is applied:
>l
RH offset : 0.00000000E+00
RH gain : 1.00000000E+00
T offset : 0.00000000E+00
T gain : 1.00000000E+00
5. If some RH offset or gain is applied, write down the adjustment
and then clear it by writing zero to RH offset and one to RH gain
using the LI command:
>li
RH offset : 0.001300000E+00 ? 0
RH gain : 1.040000000E+00 ? 1
T offset : 0.00000000E+00 ?
T gain : 1.00000000E+00 ?
6. You must now prepare a list of 3 ... 6 correction points using a
humidity generator or salt solutions (for example, using the
HMK15 Humidity Calibrator). You must measure the transmitter’s
RH reading at each point, and make a note of the reference RH
reading. Here is an example list for a four-point correction:
Table 35 Example List for Multipoint Correction
Point Number Transmitter’s Reading Reference
1 12.2 %RH 11 %RH
2 34 %RH 33 %RH
3 75.5 %RH 75 %RH
4 97.3 %RH 97 %RH