My aim is to acquire signals on external trigger on a PXIe 6368 DAQ card, do some basic processing and store them.
Everything works as it should, just the timestamps are that comes with the measurements are not really what I wanted.
My findings (please correct me if I'm wrong or could be set any other way):
- When acquiring on external trigger, t0 is the time of DAQmx Start Task.vi execution, not the time of trigger
- When acquiring measurements in retriggerable mode timestamps are not defined by each trigger but instead equidistant (with set sampling rate) from execution of DAQmx Start Task.vi. (e.g. if DAQmx Start Task.vi executes on time 0 and triggers come each ms from t=2s on and sampling frequency is 1MHz, timestamps would be 0, 1E-6, 2E-6,3E-6...; Instead I would want 2, 2+1E-3, 2+2E-3, 2+3E-3...) - it looks like DAQmx driver is taking 1 retriggerable measurement as samples were acquired with one frequency - as there were no pause between triggers.
Is there any way of getting t0 of waveforms on the time of trigger - at least relative distance to be correct?
Is there something that I did not configure right?
Is there a workaround?
I found a similar issue HERE, but was somehow not answered.
Photos in the attachment show my implementation.
Any information would be really appreciated as this is quite a hurry.
