The following procedure describes a temperature (T) measurement calibration using serial line commands. You can use the procedure to do a one-point calibration (offset) or a two-point calibration (offset and gain). For two-point calibration, the second reference point must be at least 20 °C warmer than the first.
Temperature measurement is not controlled by the trimmers, so do not adjust them during temperature calibration.
- Connect the USB cable to the service port on the module, and to a USB port on your PC.
- 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.
-
Verify that the connection works by giving the ? command:
>?
If the module does not respond with device information:
- Check that the module is powered
- Try the ?? command in case the module is in POLL state, open the line using the OPEN command if necessary
- Check your serial line settings and cable connections
- Power off the module, unplug the USB cable, restart the terminal application, and try again
-
When your serial connection is working, use the L command to see the current user adjustment parameters and the status of the trimmers. Write down the T
offset and gain values so you can restore them manually using the LI command, if necessary.
>l
-
Use the ERRS command to see that no errors are active:
>errs
-
Use the PASS command to enable the advanced commands:
>pass 1300
- Insert the probe in the temperature reference and wait for 20 – 40 minutes for the reading to stabilize.
- Give the CT command. The output from the command shows the currently measured T value, and prompts you to enter the value of the reference 1. This is the reference on the colder end, which produces the offset correction for the measurement.
-
You now have three choices:
- To apply the correction, type the temperature of the reference in degrees Celsius and press ENTER.
- To exit the CT command without adjusting the measurement, press the ESC key and exit this procedure.
- To refresh the measured value without typing in the correction, press ENTER.
-
If you only want to perform a one-point calibration (offset correction), press the ESC key after entering the correction. The CT command will exit, and you
can move to 13.
>ct T 21.9847 Ref1 ? 22 Press any key when ready OK >
To continue with the calibration of the warmer end (gain correction), press ENTER.
- Insert the probe in the second temperature reference and wait for 20 – 40 minutes for the reading to stabilize. The measurement reading for the second point will appear when the measured temperature is at least 20 °C warmer than the first reference point.
-
Type the temperature of the second reference point and press ENTER to apply the correction.
T 44.9847 Ref2 ? 45 OK >
The CT command is now finished and both adjustments have been applied.
-
Use the L command to verify that the new user adjustment parameters are in use:
>l
-
Use the SAVE command to save the changed settings:
>save Saving settings...done >
- Measure the value of the analog output to verify that the measurement is OK.