USB 6210 polling rate

[XAttendu]

Hi all,

I am running a Labview software that reads a counter on a usb 6210. The DAQ is connected to a function generator (FG) outputting a TTL signal at a given frequency. I have noticed that when I increase the frequency past a certain frequency (dependant on the machine I am running the software on about 1kHz on one and around 2.4 kHz on the other), the counter skips certain counts. I am aware that the DAQ doesn't actually miss the counts, however I am not able to poll it fast enough to see the incremental counts past a certain limit. After some investigation and research it seems that the bottleneck is in the USB polling speed in the DAQmx READ function. Also, buffered measurements are not a solution in this particular application. I really need to repeatedly poll the device for single samples.

Does anybody know a patch to reduce this delay ? Even small improvements are welcome. I have already made sure to disconnect any other USB devices. If this is an OS induced delay is there any way to edit the system parameters to increase USB polling ?

Thanks in advance

[crossrulz]

This definitely sounds like an OS issue.  Windows just won't let you keep up.  You could try a PCIe or PXI setup, which will reduce communication overhead with the DAQ.  But I still suspect you will miss counts as long as you are using Windows.  You may need to move to a Real Time OS or an FPGA DAQ.

[Henrik_Volkers]

even 10kHz shouldn't be a problem. I expect the solution in your software.

Can you attach the vi?

[XAttendu]

Hi Henrik,

I really hope you are right ! 10 kHz would be amazing. You'll find the simplified .vi below it should work with any NI USB DAQ as the code was adapted from the examples provided by NI. Thx for your help!