|You can also use Vaisala Insight software for performing calibration and adjustment. See Vaisala Insight software.
To perform a 1-point adjustment to the capacitance measurement of the HMP110 or HMP113 using serial line, you need:
- Vaisala USB cable (item code 219690)
- PC with a terminal application
- One humidity reference. 1-point adjustment with a single < 50 %RH reference adjusts the offset parameter of the measurement. 1-point adjustment with a single > 50 %RH reference adjusts the gain parameter of the measurement.
The following example procedure uses the HMK15 Humidity Calibrator. LiCl salt (11.3 %RH at 25 °C) is used as the reference point.
|For more information on using a humidity calibrator and salt chamber references, see Vaisala Humidity Calibrator HMK15 User Guide M210185EN.
- Connect the USB cable to the PC, but do not connect it to the probe yet.
- Remove the filter from the probe and insert the probe in the LiCl salt chamber of the humidity calibrator (11.3 %RH).
- Start a terminal application and set the correct connection settings. The default serial settings are 19200 8 N 1. Remember to check which COM port the USB cable is using.
- Wait for 20 … 40 minutes for the humidity to stabilize.
- Start the terminal session and connect the USB cable to the probe. If your probe is in the analog output mode, press ENTER a few times to start it in RS-485 mode.
Verify that the connection works by giving the ? command.
If the probe does not respond with device information:
- Disconnect the USB cable from the probe and retry. If your probe is in the analog output mode, press ENTER a few times immediately after connecting the USB cable.
- Try the ?? command in case the probe is in POLL mode, open the line using OPEN command if necessary.
- Check your serial line settings and cable connections.
When your serial connection is working, use the L command to see the current user adjustment parameters.
Use the ERRS command to see that no errors are active.
Give the CRH command, with the %RH value of the
reference as a parameter (in this case 11.3 for LiCl).
crh 11.3 OK
- Check with the L command that the user adjustment parameters have changed.