ni 9234 fifo dma dropping samples

[leapingfrog]

Hi,

I've got an issue when sampling using the cRIO and an AI card NI 9234, Currently configured to sample a 1k Hz signal from signal generator on FPGA side going directly to DMA which is (1023 elements in size) to the host side (1 million element size). Using producer, consumer architecture and saving to tdms on the consumer side. The producer has the read from dma fifo. Please see images any help would be great !

If i plot the data i get this :

Here is my FPGA code :

 Here is my host side :

[Supreeth.K]

Hi leapingfrog,

To get the shape information of a signal, you need to generally sample at a rate of 5-10times the frequency of the signal. In your case since the signal frequency is 1kHz, you need to sample at a rate of 5-10 kHz (the higher the better). You can change the data rate of the module to a higher value (maybe 10.240ks/sec) and check if this makes things better.

Thanks and Regards,

[leapingfrog]

Hi,

I tried sampling at higher rates, basically i tried all the available settings all the way up to 51.2k s/s and i still get a graph like i've posted. The only difference i notice is when i drop the input signal to 10hz, then it works.  Anything above that i get the same problem. I thought it could be with a specific setting. I change the sampling rate then simply save the vl file and rebuild the project deploying to the cRIO.

Do you have any other suggestions as i'm kind of stuck

[leapingfrog · Accepted solution]

Hi,

The issue has been resolved on this post. 

Thank you