DAQ accuracy from calibration report?

[-Raul-]

Hello,

I have a last minute problem in my first PXI project: the accuracy of the DAQ chosen (PXI-6229) is too low in the 10V range (3,100uV) to measure a 1mV signal accurately. In my project I have 6 signals that require that resolution in the 10V range, so unfortunately I need that accuracy.

Checking the calibration certificate from that DAQ, the "deviations" recorded were quite low (less than 20uV). Can I assume that the DAQ is good enough to measure that 1mV based on the calibration report data?

If there is no other option but to change the PXI DAQ for another one with higher resolution, can I just swap the PXI-6229 for the higher accuracy "PXI-6289"? Are they pin-to-pin compatible (i.e. no hardware/software would be needed)?

Thank you!

[Eden_S]

Hi Raul,

Thank you for your post.

The value you stated is that minimum accuracy of that device at a reading of 10V. Of course, the absolute accuracy will change depending on the value you are reading. Will the measurements you are taking that require this resolution also be around 10V or are they going to be considerably lower?

The calibration data can give a good indication of the kind of results you would expect to see with your device. However, the accuracy can depend on a number of environmental factors so I wouldn't exactly say it is 'safe' to assume that you will get the same deviations in your measurements; we tend to recommend you take the lower limit of the accuracy as what is expected, simply so you are 'prepared for the worst-case scenario'.

Finally, it seems that the pin layout of the two cards you mentioned are in fact the same and they both use the same drivers (DAQmx) so they should be fairly easy to replace with each other.

Best regards,