Incorrect Thermocouple's Measurements in Labview

Updated May 8, 2019

Reported In

Software

  • LabVIEW
  • Measurement & Automation Explorer (MAX)

Driver

  • NI-DAQmx

Issue Details

I'm able to read correct measurements from my thermocouples using DAQ Assistance and NI MAX, but not when I create my own LabVIEW code using DAQmx functions.

 

Solution

When using tools like DAQ Assistance or NI MAX to acquire measurement from thermocouples, notice they automatically assign a number to the "CJC Value" setting:

Unlike in the case of DAQmx where you need to make sure to Add those constant values to your code:


 

Additional Information

What is a Cold Junction Compensating (CJC)?
A thermocouple measurement always is made from information from joined wire end (hot junction) and open wire end (cold junction) also called reference point. 
If the reference point fluctuates, even if the hot junction does not, the measurement data will fluctuate too. For this reason, the variations from the cold junction need to be monitored and compensated with a CJC (Cold Junction Compensation) measurement in order to keep it at 0°C.

 
 

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