Owner manual

n Always wait for measurement instruments to stabilize in the ambient

temperature. Temperature differences are a major source of measurement

error.

n Check that there are no heat or moisture sources near the transmitter.

n Check that the transmitter is not in direct sunlight or close to the discharge of

the supply air ducts.

n Check that there is no moisture on the probe. If the sensor has become wet,

you must allow it to dry before you can measure.

Adjustment Types

You can perform a one-point calibration and adjustment with Vaisala hand-held

meters that utilize the MI70 measurement indicator (for example, HM70). See the

following sections:

n Calibration and Adjustment Using a Hand-Held Meter and a Reference

Probe on the facing page

n One-Point Humidity Calibration and Adjustment Using a Hand-Held Meter

and HMK15 Humidity Calibrator on page45

Connecting to the service port using a computer and a terminal program allows

you to perform calibration and adjustment tasks using serial commands. You

can, for example, perform a two-point humidity calibration and adjustment, or

clear the existing user adjustments (factory calibration will remain). See the

following sections:

n Calibration and Adjustment Commands on page36

n Two-Point Temperature Calibration and Adjustment using a Computer on

page49

n Two-Point Humidity Calibration and Adjustment using a computer and a

HMK15 Humidity Calibrator on page46

If you replace the HUMICAP

humidity sensor of the

transmitter, you must perform the two-point humidity calibration

afterward.

Adjustment Points

HMDW110 series transmitters have two adjustment points for both humidity

measurement and temperature measurement:

n The first point (low point) affects offset across the entire measurement range.

For humidity adjustment, the low point must be < 50 %RH.

5 Maintenance