SCXI-1102/1303 Temperatures Incorrect

[pbrincat]

Our configuration is a NI PCI-6259 card, connected to a SCXI-1000 chassis with SCXI 1102/1303 for thermocouple readings and SCXI1302. The card is also connected to a SCB-68.

The issue we are having is that the thermocouple values from the SCXI-1102/1303 are being impacted by the sample rate we acquire at. For example if we create a task in the Measurement & Automation Explorer that only has SCXI-1303 channels 4 & 8 using the in-built cold junction, temperatures are only being read accurately if we sample at less than about 700Hz. If we exceed this rate then the thermocouples reading the room temperature on an N-sample acquisition start off ok but then rise unrealistically by 30-60°C depending on the sampling rate.

I understand that the SCXI-1102/1303 is capable of sampling at 333kSample/s, and given we’re sampling in affect 6 channels (ch4 through to 8 + cj) then maximum sampling rate should in the order of 55kSample/s. Is there something wrong with this calculation or is there some other reason why we’re not getting realistic temperature values anywhere near the maximum sample rate.

Thanks

Paul

[pbrincat · Accepted solution]

Found that this problem was related to a bent connector pin on the 1349 feed through panel. Fixing this pin resolved the sample rate issue.