NI 9213 CJC value and re calibration

[HHNB2001]

Hello,

I have an old NI 9213 TC reader that was last calibrated in 2013. When I read the internal CJC value I get around -81 Celsius. Is this extreme value a result of missing many years of calibrations? Or could there be a separate issue? The project this is connected to has been shelved for a long time and it's just now getting picked up again, so I'm trying to discover how the whole system works.

Thank you!

[santo_13]

Shouldn't be that bad when out of calibration, can you check by connecting a TC and see if the measurements are reasonable?

[HHNB2001]

I did try two different TC reading methods through lab view. I tried DAQ assist and that gave a TC value of about -92 Celsius. I also tried the NI DAQmx >> Create channel and that showed a TC value of around 14-16 Celsius. Using the same TC with an external meter generated an ambient temperature of 21 Celsius.

I am new to Lab View so there is a big possibility that I am using these programs wrong, but it is very confusing to me that these two methods giving such different answers.

I have considered using the Calibration Wizard under the DAQ assist, but I am unsure if that will be helpful in the long run. 

Thank you

[HHNB2001]

Quick update, I dug around a bit more on lab view and found that I could in fact get the two methods to match if I read the CJC value and input that temperature value into the DAQmx create virtual channel for the TCs. Previously the CJC had a constant value instead of using the built in value, which is what the DAQ assist was doing. So now my two TC reading methods match. 

However I still have the issue of my CJC reading as -81.7 C and my TC in room temp reading -92 C. I'm not sure if I can do an internal calibration, or if I need to figure out how to do a full external calibration? If I do a channel calibration will that value be saved permanently or will it need to be redone each time?

Thank you so much