Vaisala hmt120 - Page 57

8. Insert the probe into a known reference temperature (if Vaisala Humidity Calibrator
HMK15 is not used) and let the temperature reading stabilize.
Do not touch the adjustment buttons before the conditions have stabilized.
9. Using the - and + buttons, make the temperature oset adjustment by making sure the
I
out
current is correct (you have to press either - or + at least once even if the value is
correct) and press the ADJ button. The red indicator LED begins to blink faster (400ms
cycle time).
If you do not wish to perform the two-point T adjustment at this time, press
the ADJ button one more time. The red indicator LED is turned o and the
transmitter returns to normal mode. The calibration procedure is now
finished.
10. Insert the probe into another reference temperature.
Do not touch the adjustment buttons before the conditions have stabilized.
11. Using the - and + buttons, make the temperature gain adjustment by making sure the I
out
current is correct (you have to press either - or + at least once even if the value is correct).
12. Press the ADJ button one more time. The red indicator LED turns o and the transmitter
returns to normal mode. The calibration procedure is now
finished.
In case of calibration error, both LEDs blink alternately at a very fast rate (cycle
time 200ms) for a period of 2s after which the transmitter returns to normal
mode.
If your transmitter has the optional display, the following notifications are shown
on the display during calibration:
• Probe cal: RH 1 (corresponding the green LED blinking slowly)
• Probe cal: RH 2 (corresponding the green LED blinking fast)
• Probe cal: T1 (corresponding the red LED blinking slowly)
• Probe cal: T2 (corresponding the red LED blinking fast)
• Probe cal: Error (corresponding both LEDs blinking alternately at very fast
rate)
Chapter 6 – Calibration and Adjustment
55