Unexpected Temperature Measurement With NI Thermocouple Module

Updated Jun 7, 2019

Reported In

Hardware

  • NI-9213
  • NI-9214
  • NI-9210
  • NI-9211
  • NI-9212

Driver

  • NI-DAQmx

Issue Details

I am acquiring voltage with a thermocouple module, but my voltage is railing. For example, with the NI 9213, I am constantly reading 0.07812 V. Why is this happening?

Solution

1. Ensure the thermocouple is wired correctly. Refer to a thermocouple color code guide to see wiring specifications.

2. Refer to the specific module's Getting Started Guide to verify wiring considerations. 

3. Refer to the Unexpected Voltages, Floating or Crosstalk in Analog Inputs document. Specifically, NI does not specify what the device will read for an unconnected channel. Ensure that you are measuring a connected channel.

4. If you are still reading unexpected voltages or temperature, refer to this thermocouple measurement tutorial.

5. Lastly, ensure that the voltage range you are measuring is within the specification of the device. For example, the range of the 9213 is +/- 78 mV. Check for the voltage with a multimeter and check for a module that can accommodate it.

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