Analog output not working properly for long waveforms

[Georgeq]

Hello. I am using the PCI-6110 analog output(channel 0) to generate a chirp signal from 50 kHz to 500 kHz, with a sampling frequency of 4 MS/s. At the same time, I am simultaneously recording data in channels 0 to 3 of the DAQ board at 5 MS/s (taking 220000 Samples in each channel).

 If my waveform is shorter than 18 ms, my applications is WORKING just fine. If I increase the pulse length of the waveform (i.e. 30 ms), the generated waveform has unstable behaviour: sometimes it is correct, but sometimes it is only half of the chirp.

  Is this a problem f speed of my PC? or is there something wrong in my application?

  I am attaching my application and two text files corresponding to two chirp waveforms (one that works properly since it is 1 ms and one that doesn't, 30 ms ). To run the application, first "LOAD" the text file and then "PING". You can indicate the "Smples per Channel" as 220000 and the "Sample Rate (Hz)" as 5000000.

[Brad_K]

Hi Georgeq,

Your VI is calling DAQmx Is Task Done on the AO task, which does not wait. I think that it should call DAQmx Wait Until Done instead.

By the way, if you call DAQmx Stop Task, you should get warning 200010, "Finite acquisition or generation has been stopped before the requested number of samples were acquired or generated". DAQmx Clear Task does not report errors encountered during task state transitions.

Brad