Need assistance calibrating a NI 9214 module.

[CFER_STS]

I am attempting to perform a calibration of a NI 9214 module, as per the instructions in the NI 9214 Calibration Procedure.  All calibration equipment is as per recommendation, with the exception of the calibrator, which is a Fluke 5700A (Fluke 5520A is the recommended model).  I have the cDAQ-9178 chassis setup per the procedure document.  Using LabVIEW 2014 SP1, NI-DAQmx 14.5, and most recent IVI drivers.

My VI has successfully read the TC channel voltages, all of which are within the published specs.  The problem I have is with the CJCs.  Outputting the calibration resistances as per the procedure, and using an AI Voltage task to make measurements and converting to resistance as per the equation given in the document, instead of 1000, 19000 and 100000 ohms, I am measuring about 680, 3280 and 3900 ohms (as converted from measured voltages).  This is consistent from trial to trial, in both high speed and high resolution modes, and across NI 9214 modules (I have seven).  There is nothing obvious in the code or calibrator setup that would indicate a problem.

Anything else to check or modify?  I can't figure this out.

Sean

[fromm8]

Hello

Are you using the TB-9214 or the NI-CAL 9214?

Regards

Frank R.

[CFER_STS]

NI CAL-9214, as per the calibration procedure document.

[fromm8]

Hello CFER-STS

We are going to be testing that set up on Monday. We are going to communicate next steps.

Regards

Frank R.

[CFER_STS]

Anxiously awaiting your reply.

[fromm8]

Hello CFER-STS

The set up was tested and we were not able to reproduce your behavior in our end since it worked. 

How are you connecting the COM and Ground Lug?

Regards

Frank R.

[CFER_STS]

NI CAL-9214 COM terminal and cDAQ-9178 chassis ground screw both connected to ground output of the Fluke 5700A. 2-wire compensation mode on, (external sense on), connections as per the calibration procedure.

[fromm8]

Hello CFER-STS

I see, do you have only one NI CAL 9214?

Regards

Frank R.

[CFER_STS]

Yes, just the one.  As a check - what should the resistance across the CJC terminals be if I measure them directly?  Also, see below for the measurement task code.  Is anything obviously wrong here?

[rachelpriester4]

Currently you are reading as many samples as are on the buffer instead of the number of samples between 8 and 130 as you are defining on your DAQmx Timing VI. To fix this, you should branch off the wire that is outputting from your selector function such that the samples between 8 and 130 are the ones you are reading in the DAQmx Read.