Hi Jex,
If you want to actually get a good temperature reading from your thermocouple, I don't recommend to connect it directly to the AI of the 6008. If you look at the specs of the board, the minimum voltage range for the AI is +/- 1 V. with the 12-bit resolution you'll be able to read about 480 uV with a 37.5 mV accuracy, but the thermocouple will give you a value only whithin it's range, not the board's range. If you consider that thermocouples typically have sensitivities of around 50 uV/°C (depending on the type), I really don't think you'll get the performance you want.
It's always recommended to have some sort of signal conditioning (amplification in this case) in order to get the most out of the hardware. The point is to make the thermocouple's signal go as near as possible to the range limits, so that you can take advantage of the full range scale.
If you're interested in this kind of performance with USB connectivity, you should take a look at the USB-9211. I've used it and it's pretty straight forward. Just plug it and it will do all the signal conditioning for you.
Check this two other posts for more information about this topic.
I hope this helps.
Have a great day and thanks for using NI forums.
Arturo Vargas
National Instruments de México
