Calibrating and adjusting HMT120 and HMT130 series transmitters - HM70 - HMT120 - HMT130

HM70 User Guide

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User guide

You can check and adjust HMT120 and HMT130 relative humidity measurement with HM70. An HM70 connection cable is needed (Vaisala item code 211339).

There are 4 types of adjustments available: field checking and adjustment using a calibrated reference probe, 1-point adjustment using a calibrator, 2-point adjustment using a calibrator, and LiCl-NaCl adjustment.

First carry out 1 … 7. After 7, choose 1 of the alternative methods for completing the adjustment.
To begin the adjustment:
  1. Connect connection cable 211339 to the SERVICEPORT connector on the HMT120/HMT130 component board.
  2. Connect the other end of the connection cable to either one of the connector ports located on the bottom of the MI70 indicator. See Figure 1.
  3. Switch on both devices (or only the MI70 in case HMT120/HMT130 is on continuously).
  4. The reading of the transmitter is shown on the top or middle row of the MI70 indicator display, depending on which connector port the connection cable is connected to.
  5. Press the ADJ button on the HMT120/HMT130 component board to open the adjustment mode. The LEDs on the component board remain in OFF state, and a notification about starting the adjustment mode is shown on the MI70 display. If the HMT120/HMT130 transmitter has the optional display, the text MI70 adjustment mode is shown on the upper row of the display.
    CAUTION From this point onwards, the local adjustment buttons of HMT120/HMT130 are disabled and the adjustment is carried out using the MI70 indicator. Take care not to press the MI70 buttons too quickly during calibration, or the calibration may fail. Wait for 1 second between button presses. HMT120/HMT130 display and analog outputs always follow the actual measured RH/T value when in MI70 adjustment mode.
  6. Press OK to start the adjustment.
  7. Check the environment settings if needed. Otherwise press NO. Complete the adjustment using 1 of the following alternative methods: