Vaisala DMT132 - Manual (Page 47)

Chapter 4 ________________________________________________________________ Operation
VAISALA _______________________________________________________________________ 45
Adjust Capacitance Measurement
Use the CRH command to perform a one-point or two-point correction to
the capacitance measurement of the transmitter. This command changes
the offset and gain of the measured capacitance, and therefore affects
humidity measurement over the entire temperature range.
CAUTION This command should be used only when the HUMICAP® sensor has
been replaced, or the measurement has drifted significantly. For normal
adjustment, use the RHCAL command instead.
CRH
When performing a one-point adjustment, you need to place the
transmitter in a single humidity reference with RH < 50%. Run the
command and enter the exact RH of the reference after the measurement
has stabilized. Exit the command by pressing the ESC key before
proceeding to the second point (see example 1 below).
For two-point adjustment, the first point requires a RH < 50% humidity
reference, the second point must be RH > 50%. There must also be at
least 30 percentage points of difference between the references. The
measurement reading for the second point will appear when this
requirement is met.
Example: one-point adjustment
>crh
RH: 11.41200712 Ref1 ? 11.3
Press any key when ready
OK
>
Example: two-point adjustment
>crh
RH: 11.41200712 Ref1 ? 11.3
Press any key when ready
RH: 74.72910210 Ref2 ? 75
OK
>