Digitizer Sample Rate Values

[JayWW]

Hello,

    I'm trying to determine the proper value if samples to take to properly acquire a measurement via the digitizer. 

A little background: I'm developing a VI that measures THD on an amplifier. I'm putting in a quick 20 cycle (+/- ramp cycles) burst into an amplifier. So I need the digitizer to skip the first few cycles and only take measurements on the middle 10 cycles. My arb waveform generator and digitizer are both sync'd with an external clock, but I'm getting some weird numbers and need to tweak either the number of samples the digitizer takes, or possibly where the digitizer is taking the measurement. There's a wide range of frequencies that I'm measuring, say 50Hz up to 500kHz, so the digitizer needs to adapt to the frequency. 

I've attached my code and the measurements take place in the ADV SHELL.vi, in the  ADV GO.vi. I think what might need to be adjusted is the Num Samples value as seen in the image below. (Found in the ADV GO.vi)  Any help would be appreciated!

[psuedonym]

Are you using NI boards?

[JayWW]

Hello,

    Yes. My clock signal is supplied by a PXI-5404, the ARB signal is supplied by a PXI-5421 and the DIGI (used as a scope) is supplied by a PXI-5122.

Thanks, 

Jay

[psuedonym]

I don't know if this is a programming issue or a LabVIEW issue.

There is also a forum devoted to DAQ https://forums.ni.com/t5/Multifunction-DAQ/bd-p/250

[JayWW]

Thanks for the info. I think I've figured out the issue. The digitizer was losing it's hardware label after the first iteration after initialization. I passed everything through a shift register and now it seems to be working. 

--Jay