Thermocouple measurement directly into USB DAQ

hi , with regards to the above matter..
i'm having complications using the DAQ to take measurement directly from the thermocouple..
im currently using the acq thermocouple sample.vi to take the temperature reading..
but what does the cold junction constant means ?
i am unable to figure out what it implies
using the default settings of constant and 25 degree CJC value
the temeprature reading fluctuates a lot ranging from negative few thousdand degrees to slightly above 200 plus degrees..
thanks in advance

The 6008 has 12 bit resolution and a range of +/- 1 volt, this means the smallest change in voltage that it will measure is about 0.048 Volts. The sensitivity of a K-type thermocouple is 41 µV/°C this means that you will only be able to measure a change of temperature that is about 10 °C. Also, if you have any noise in your setup it will make it look like the temperature is jumping around in huge increments. I dont know that this is your problem but it is definitely something to keep in mind.
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