temp measurement fluctuate ALOT in Labview -daq 6008

[fash_ford]

I bought a USB-6008 12bit DAQ

I have problem with temp. measurement as it jumps from 0'C to 100'C, so random.

I have put a K-type T/C across AI0 &AI4 [ana. input] and I am using NI 'Acq Thermocouple sample.VI' it shows the temperature is not realistic.

What is wronge with my setup please?

Thanks

[johnsold]

First you will not get very good results using a thermocouple directly with the USB-6008. The resolution on the +/-1 V scale is ~0.5 mV = ~13 degrees C for a Type K thremocouple at zero C.

A 100 degree jump corresponds to about 4 mV.  Unless you have been very careful about noise, you may be picking up that much noise on the TC wires.

Are your thermocouples grounded? Are you getting ground loop currents which may be interfering?

Lynn