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If that thing is just an analog input module, you'll never read a bimetallic sensor voltage reliably. You need a thermocouple amplifier ("thermocouple input module" in NI-speak).
BTW, Isn't CJC indicative of an actual sensor on the cold end and not just a constant value?
Yes, the Cold Junction Compensation sensor is an active measurement. Each dissimilar metal interface produces a voltage, including where the thermocouple wires meet the DAQ connector. However, if you know the temperature and metals of a junction you can factor this out and know the voltage at the thermocouple tip; hence the need for a sensor at (though in reality it is just near, and the environment around it is assumed to be consistent) the DAQ connector.