NI-DAQmx for CompactRIO Acquisition Rates

Updated Apr 17, 2020

Reported In

Hardware

  • cRIO-9040

Software

  • LabVIEW

Driver

  • NI-DAQmx

Issue Details

I am using a CompactRIO that support NI-DAQmx (such as a cRIO-9040).
I want to acquire data faster than 5 kHz, is this possible?
What rates can I acquire from my modules at?

Solution

It is possible to acquire data faster than 5 kHz using a NI-DAQmx enabled cRIO.

The acquisition sample rate is limited by the Sampling Rate specification for your specific C Series Module.
You would use the DAQmx Timing VI to configure your samples rates. 

Data is streamed to the buffer on your cRIO's Real-Time Operating System, and pulled off of the buffer with the DAQmx Read function. Consult this article for more information on timing and buffers.
Specifically for Hardware Timed Single Point acquisition (continuous streaming without a buffer), the update rate is 5 kHz, per the specification on this White Paper

However by pulling more than 1 sample in per DAQmx read, you can increase the overall acquisition rate. For example, reading 10 samples per DAQmx read, at a rate of 5 kHz, gives an overall rate of 50 kHz. 

Additional Information

When using DAQmx with the cRIO, you need to configure the module's programming mode to Real-Time(DAQmx)