NI9234 sampling rate - LabVIEW FPGA

[far_nia]

Hey guys,

I have very simple question. I am checking a sample code in labview examples for NI 9234. what is the difference between data rate and samples per channels?

If we read with maximum data rate which is 51.2 KS/s (reading 4 channels), so the samples per channel should be 51.2/4=12.8 KS/s/ch . am I right? if this is correct, what is the sample per channel control in the FPGA vi?

[Dennis_Knutson · Accepted solution]

The rate is how often a sample is taken by the a/d. The sample count is how many of those samples you return to the program. For example, if you had a rate of 1000 samples per second you could request 500 samples which would take 500 ms to acquire. At a rate of 2000 samples/sec, requesting 500 samples would take half as long. Keeping the same 2000 samples/sec and requesting 2000 samples, we are back to to 500 ms to acquire.

[far_nia]

Thanks for the quick reply. but could you please explain your sentence one more time: "if you had a rate of 1000 samples per second you could request 500 samples which would take 500 ms to acquire" where does this "500ms" come from? I am a little confused by your answer 

[Dennis_Knutson]

p.s. You adjust the sample rate to adjust the detail of the waveform you wish to capture. A rate of 2000 samples per second has resolution twice that of 1000 samples per second.

[Dennis_Knutson]

It's just basic arithmetic. Doesn't it make sense that if you had a rate of 1000 samples per second and requested 1000 samples, the acquisition would take exactly 1 second? Time to acquire is number of samples divided by samples per second.

[far_nia]

got it! 

[far_nia]

got it!