Thermocouple offset error w/ CJC

[Kaleb_A]

So at a range of +-0.2 V, and the PCI-6221 has a 16 bit ADC, the ADC's code width (smallest detectable change) is equal to (0.2 -(-0.2)/2^16 = 6.1 µV.

[Kaleb_A]

Let me check to see if setting to K-type changes the range. That may just adjust the way the cold junction compensation performs.

[Kaleb_A]

I believe that using a temperature acquisition will be more beneficial than regular analog input. You're right in that it should configure the device accordingly.

I'm sure you have, but did you configure the board to have that accessory in NI MAX by right clicking on the PCI-6221 and choosing 'Configure'?

Have you tried creating a task in NI MAX and observing the channel temperature value when you click 'Run'?

What is the value you have for CJC Source, Constant, Built In, or channel?

What acquisition mode? How many samples are you reading? At what rate? 

What is your lab/measurement environment like? Is your thermocouple/DAQ near any power equipment?

How long have you owned this PCI-6221? When is the last time you had it calibrated, or performed a self-calibration?