DAQmx Engineering Unit Conversion

[neesea]

Hello,

I'm looking for some information about how DAQmx converts certain measurements to engineering units.  Specifically I'm interested in RTD and Thermocouple measurements.  I would assume DAQmx uses a standard NIST equation to convert voltage to temperature, but I can't actually find any specific documentation to that effect.

[NIYiran]

Hi votton,

We use the Callendar-Van Dusen Equation to calculate RTD measurements. See this page for more information: https://knowledge.ni.com/KnowledgeArticleDetails?id=kA03q000000x1rnCAA&l=en-US

As for thermocouples, we use the NIST equations as well; this white paper has a bit more information on thermocouple theory. https://www.ni.com/en/shop/data-acquisition/sensor-fundamentals/measuring-temperature-with-thermocou...

I hope this helps!

[smuham24]

Hi there, I have a question about converting units as well. The current code that I have uses mcdaq library which contains Toeng.vi and From.eng.vi. which essentially converts engineering units. To be specific, Toeng.vi converts a single A/D count value to an equivalent voltage value and Fromeng.vi converts a single voltage (or current) in engineering units to a D/A count value for output to a D/A. my current code uses these two vi's to convert engineering units for mcdaq and I am looking for replacement for these because these are not compatible with the DAQmx driver library. So, I need some help on the replacements of these conversion factors from mcdaq to daqmx drivers> Any help is appreciated. 

Thanks