SCXI 1102 CJC built-in not available

[Will_Crowe]

I have an SCXI 4-slot chassis as part of a larger PXI chassis and when I go to set up thermocouple channels on one of 2 SCXI 1102 cards, the option to select 'builti-in' as the cold junction is not appearing. I want to use the built-in thermistor on the card as the reference channel. Do I have to enable that in some way, first, through MAX?

Will

[Jamie_S.]

Hi Will,

I'm Jamie, an Applications Engineer at NI.

Thanks for your post, the CJC sensor is located on the terminal block interfaced with the SCXI-1102 and is addressed using a special character string.

Provided you can see the SCXI system in MAX you can then create a Virtual Channel for your CJC sensor ensuring that the correct SCXI module is selected and not the PXI DAQ card. When setting up your CJC Virtual Channel you should have been presented with the "Built-in" option, however if this is not the case you may need to install a newer version of DAQmx from our "Drivers & Updates" page here (latest version is 9.4).

If downloading and installing a newer version of DAQmx is not possible it is still possible to read CJC temperature using the "User Supplied" CJC temperature, please refer to the KB article here which details this method. The KB also includes a table of the special character strings for the SCXI-1102 module and the compatible terminal blocks.

Hope this helps with your application Will, please keep me informed on your progress and if I can be of further assistance.

Thanks

Jamie

[Will_Crowe]

Hi Jamie,

Thanks a million for getting back to me. Since I posted this query, I realised that the 'accessory' was not specified (in this case a TC 2095) and when I did this, the 'built-in' option appeared. I never realised that this built-in sensor was on the accessory and not on the card. Your other comments have added to my overall understanding of this in any case.

Regards,

Will