NI 9214 Voltage Measurements

Updated May 3, 2018

Reported In

Hardware

  • NI-9214

Driver

  • NI-DAQmx

Issue Details

I have an NI 9214 thermocouple module, but I'd like to use it to measure voltage because of it's high resolution.  How can I do this and what kind of accuracy can I expect?

Solution

NI recommends using a voltage specific module to get the best accuracy on your measurements.  The NI 9214 is designed specifically to be used for thermocouples.  In the specifications, the measurement accuracy is listed with respect to the type of thermocouple being used.  The module will automatically attempt to apply cold-junction compensation to the measurements.  The OTD current used by the module will also distort the measurements.  The accuracy will vary on whether they use high-speed or high-resolution mode for the module.

Additional Information

Although not supported by NI, in order to read voltage from the NI 9214 you should do the following:

Disable CJC
Disable OTD
Set module for high-resolution
Set DAQmx task to return raw values
Create a custom scale for voltage based on signals from a known signal source

There are not published specifications when using this device in this way.

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