what is the maximum accuracy of PXI-4472?

[MVK]

What is the maximum accuracy of PXI-4472?
When I was doing testing, some channels giving more than 10mV difference. Say for example my input is 5volts.but my DAQ card reading around 4.990volts. So eventually I am getting 10mV difference, which is not desirable. Is there any settings need to be done in the hardware (4472) or software?

[SnarrVIEW]

Since the 4472 has 24 bits of resolution the accuracy will be around +/- 1.2uV. You should not be seeing 10mV of error, are you sure that your voltage signal is truly 5.000V? Could you measure the 5V signal with a DMM to make sure that it is indeed the 4472 giving you an incorrect reading and not the signal itself. If it is the 4472 you might want to calibrate the device. You can find the calibration procedure on the NI website.

Bryan Snarr
Application Engineer
National Instruments

[SnarrVIEW]

I did some further research and found the following document:
http://digital.ni.com/public.nsf/websearch/914D96F95777CBDF86256C05007774C0?OpenDocument

Also, our DSA products are not intended to be used in applications where DC accuracy is important. DSA is good for linearity, alias rejection, and dynamic range. When looking at accuracy there are 2 important #'s on the 4472: Amplitude Accuracy (+/- 0.1dB) and Flatness (+/-0.03dB). 0.1dB corresponds to about 1.0% error so if you have a calibrator generating a 5.0000V signal, we guarantee that you will see between 4.95V and 5.05V. Now this does not seem very good, but "absolute amplitude accuracy" is not the most important spec for this type of device. The 4472 employs extreme linear ADC's, this means that the error seen across all the channels is going to be the same. So if you are measuring a 5.00000V signal and you actually see 5.1V then you can be assured you are going to see 5.1V on all the channels. Another way of expressing this error is linear Gain and this inaccuracy is typically accounted for in a system-level calibration before you start taking measurements.

Let me know if this offers you any help and have a great day!