Vaisala PTU300 - Manual (Page 173)

Chapter 7 ____________________________________________________ Calibration and adjustment
VAISALA _______________________________________________________________________ 171
Multipoint Relative Humidity Adjustment
Using Serial Line
You can use the MPC RH command (introduced in software version
5.14) to perform a multipoint adjustment to the relative humidity
measurement. Due to the linear response of the HUMICAP
®
sensor, the
standard two point humidity adjustments are recommended for all users.
Use multipoint correction only if:
- You have a requirement to adjust the relative humidity measurement
in 3 ... 6 adjustment points.
- You are interested in a narrow range of measurement and want to
optimize the RH measurement performance for that range.
Multipoint humidity adjustment works by means of a correction table
that holds 2 ... 6 adjustment points. The idea is that for every point, you
enter the RH reading that the transmitter shows, and the correct humidity
reference value. You can select any references points in range 0 ... 100
%RH, but Vaisala recommends that the difference between the lowest
and highest reference point is at least 50 %RH.
NOTE Multipoint adjustment is applied “on top” of the standard user-made two
point relative humidity adjustment (done with CRH command, push-
buttons, or display). It is recommended that before you start using the
MPC RH command, you clear the existing humidity adjustment. This is
done as part of the example multipoint adjustment procedure provided
here.
MPC RH Command Syntax
MPC RH [function]
where
function = Desired function. The options are:
ON – Enable multipoint correction.
OFF – Disable multipoint correction.
LIST – Show correction table.
INIT – Start entering values in correction table.
CLEAR – Remove all values from correction table and
disable multipoint correction.