Time Uncertainty of USB-6009 DAQ

[lakshithadinusha]

Hello NI Community,

I hope this message finds you well. I was wondering if someone could assist me with a question related to measuring counts with a USB-DAQ6009. Specifically, I am using PFI 0 of the DAQ as an event counter input to measure counts in 0.4 seconds. My question is about the time uncertainty of the 0.4 seconds. Does it depend on the clock speed of the DAQ, the computer, or both?

I would appreciate any advice. 

Thank you in advance for your help and expertise.!

Best Regards;

Lakshitha

[ZYOng · Accepted solution]

It will be a software timing of the computer unless you use the Sample Clock Timing.

The system timer in Windows has an accuracy of 1 ms but it depends on what other processes are running on the computer at that instant. 

Accuracy of Software-Timed Applications in LabVIEW

If you need precision greater than 1 ms, you would need hardware timing. This is done using Sample Clock timing. However, this would require another counter to generate the sample clock pulse, and unfortunately not possible for USB-6008 since it has only one counter. Use Counter to Create a Clock for a Buffered Edge Counting Task

[lakshithadinusha]

Thank you very much ZYOng for the detailed explanation. Really appreciate your output.

I just need an estimate for error calculation.