Cold Junction Compensation (CJC) on DAQ Hardware Without Using CJC Built In

Updated Jun 13, 2018

Reported In

Hardware

  • CompactDAQ Chassis
  • Temperature Input Device

Software

  • Measurement & Automation Explorer (MAX)

Issue Details

  • I am trying to set up cold junction compensation (CJC) on my module.  It does not have built in CJC.  Is such a setup possible?  If so, how do I do it?
  • I'm trying to measure temperature with a card not designed for temperature measurement.  As such I need to set up CJC manually.  How to I do it?
  • I am wanting to use my out CJC rather than the built in one. How do I do this?

Solution

  1. Open NI MAX, and create a task on your DAQ device.
  2. Add multiple temperature measurements on the same task. 
  3. Choose the virtual channel you wish to implement CJC on.
    1. In the channel settings list, the CJC channel must be above the other channels you plan on using the CJC channel for. It would be best to have your CJC channel placed at the top of your list (see image).
  4. Under CJC Source, choose Channel
  5. Select the CJC Channel drop-down.  Your options here are other virtual channels on the task. This selected channel will be used to compensate the values of the active virtual channel selected in step 2.
  6. Be sure that the CJC channel is physically measuring the appropriate location.  It should measure the temperature at the connection between the thermocouple and the analog input for the main measurement channel.

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