How to set 9219 sample rate in LV FPGA

[David_Staab]

Couldn't find a forum for cRIO hardware, so I'll post here.

How do I dictate the NI 9219's sample rate when programming it in LV FPGA? Is the Conversion Time parameter the only factor to consider, or do more things affect the total sample time? I can't find any documents on the website that discuss the module in the context of LV FPGA (only DAQmx).

I'm trying to read voltage on ch0.

[Paul-B]

Hello David Staab,

Thanks for the post, the Conversion Time is the main property you can change using the Module Properties Window or a property node. The maximum sampling rate based on the NI 9219 specifications is 100 S/s/ch simultaneous inputs (50S/s/ch for Thermocouple). However if you need to sample at a slower rate you can implement a Loop Timer in your code to slow down the S/s.

Paul-B

[David_Staab]

If my sample loop wants to execute faster than the Conversion Time, will it be held back to a period of "Conversion Time ms", or will it oversample the data instead? Conversely, if Conversion Time is set to something smaller than the period of my loop, will the module sample at the loop period, or will my loop end up missing some samples?

In short, does the module run its own sample clock asynchronously from my LVFPGA loop that reads the IO Node, or does my loop implement a sample clock?