Vaisala HMD60 Series - Resetting Trimmers Back to Zero

It is assumed that a hole was drilled for the reference instrument during
installation, the transmitter is powered, and you can view the measurement
output value.
To adjust the output:
1. Insert the reference transmitter into the measurement environment next to the
transmitter that you are adjusting. The reference transmitter should be inserted
approximately 30 cm (12 in) from the HMD60 probe's installation hole, towards the
direction of the air flow. See Figure 9 (page 14).
2. Connect a multimeter to the analog output of the reference transmitter (connect in series
to measure the current output).
3. Wait for the measurement to stabilize fully. This may take more than 30 minutes. Monitor
the readings to see when the measurement has stabilized.
4. When the measurement has stabilized, adjust the output of your transmitter with the
trimmers until it matches the output of the reference transmitter.
Note that there is a small delay before the output value updates after turning
the trimmer.
5. When done, plug the installation hole of the reference transmitter.
7.2.3 Resetting Trimmers Back to Zero
• Computer with Windows operating system and Vaisala Insight software
installed
• Vaisala USB cable 219690 for connecting the probe
• Small Phillips head screwdriver for turning the trimmer(s)
If you need to reset a trimmer back to zero (±0 point), use the Insight PC software to restore
factory adjustments for the parameter the trimmer adjusts (RH or T).
1. Turn the trimmer(s) back to the middle position (±0 point)
2. Connect the transmitter to Insight. See Connecting to Insight Software (page 18).
3. Select
> Calibrate > Yes to switch the probe to calibration mode.
4. Select the parameter you want to reset (RH adjustment or T adjustment).
5. Select Restore factory adjustment and confirm by selecting Yes.
6. Reset each parameter (RH or T) separately as needed with the trimmer turned back to the
middle position (±0 point). The trimmer adjustment now starts from the ±0 point of the
default trimmer adjustment range (see Calibration and Adjustment Using Trimmers
(page 34)).
HMD65 User Guide M212243EN-A
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