NI-USB-6210 Signal noise issue (Analog Voltage input)

[MichaelCKW]

I recently purchased the NI-USB-6210 to replace my old voltmeter, Keithley 197A. After installation and initial testing, I found that the baseline noise was significant increased. 

For the same setting, my old Keithley 197A meter measured 5.0000+/-0.0001 V. However, the new NI-USB-6210 measured 5.00+/-0.01V. The noise is 100 times higher. 

At a lower voltage, it's 0.500+/-0.002V VS 0.5+/-0.4V. The noise is too high. According to the spec of 6210, it measures 10 V in 16 bit, and this translates to 0.1 mV. So I suspect the card may be defective.

Does anyone have the same issue? Would this be defective or could it be some settings to increase the resolution?

[Henrik_Volkers]

Well, both instruments use different approaches to measure a voltage...

Usually the most simple trick is avaraging with a windowlength matching (a multiple of) your line frequency. The 197A use filter too 😉

6210 SPEC page 4  tell something about the noise level ...

And if you use multiple channels have a look at the settling error figures on page 2 (note the log(!) scale on the y axis)

I have a 197A in my home lab rack and the only intrument that migth replace it one day would be a HP3458 😄