Pinouts for Connecting Thermistor to USB-6210

[mhschmid]

I want to connect a thermistor to a USB-6210 for cold junction calibration.  I cannot find which pinouts to use.  Can you please help?

[Brian F.]

Hello mhschmid.  In terms of connecting your thermistor to the USB-6210, you can simply take a differential measurement across two analog input channels (for example pins 15 and 16).  Then, you can configure a DAQmx task to automatically convert that voltage into a temperature by creating a DAQmx temperature task. 

In regards to using CJC with a thermistor, that isn't necessary.  A thermistor is a resistor that varies on temperature and thus does not require CJC.  However, a thermocouple requires CJC to be completely accurate since the thermocouple is composed of two different metals introducing a voltage difference at the junction of the two metals.  So, if you want to connect a thermistor to the 6210, CJC is not required.  If you want to connect a thermocouple to the 6210, then you can configure the CJC only in software (Measurement and Automation Explorer or LabVIEW) since the 6210 doesn't have a CJC sensor on it.  I hope this helps!  If anything needs clarification, I will be monitoring this forum.

Brian Fleissner

National Instruments

[jajagene]

"In terms of connecting your thermistor to the USB-6210, you can simply take a differential measurement across two analog input channels (for example pins 15 and 16).  Then, you can configure a DAQmx task to automatically convert that voltage into a temperature by creating a DAQmx temperature task. "

That's not true, at least with the combination of USB-6210 and LabView 2009.  You will get an error for a two lead thermistor.  Any guesses why?  No internal voltage or current source?  What's the proper way of using a two lead thermistor with the 6210?

[Dennis_Knutson]

You are talking about apples and oranges. Your initial question was about cjc and the answer was correct - you do not need cjc with a thermistor. You do need excitation (much different than cjc). If you specify internal excitation, then you will get an error since the DAQ card has no excitation source. You can specify external excitation and design a known current source or use something like the SCXI-1120 which does have an excitation source.