problem with analog voltage output and internal clock timing

[horatius]

OS: Labview 8.5 and Windows XP

I use the DAQ PCI 6713 card but have a problem concerning the generation of a continous analog voltage sequence (specified by a user defined array). The process should be independent from OS therefore I select internal clock and onboard buffer. Look in picture 1! I always get the error message that the buffer is too small.

Error -200609 occured at DAQmx Write (Analog DBL 1Chan 1Samp).vi:1

Possible reason(s):

Measurements: Generation cannot be started, because the selected buffer is too small.

Increase the buffer size.

Selected buffer size:1

Minimum required Buffer Size:2

Then I try to increase the buffer size and I get another error message (picture 2):

Error -200479 occurred at DAQmx Start Task.vi:1

Possible reason(s):

Measurements: Specified operation cannot be performed while the task is running.

What do I have to do, that the process works as I wantl? Why can't it be more intuitive?

Frank

[Goran Klenkar]

Hello,

I have the same thing, has no-one come up with a solution? I have scratched my head enough by now

[Antoine Chalons]

I think that "DAQmx Write" automatically starts the task if it's not explicitly done yet, the error you get in the second screen-shot comes from the "DAQmx start.vi" and it says that it can't run a task that is already running...

I suppose that if you just remove the "DAQmx start.vi" it should work.

Hope this helps

[horatius]

I solved this problem long time ago:

You have to send a waveform to the output. The red line is the waveform you have to generate first. Look here:

relating thread

there is also a link to a German LV Forum if you want to disrupt this process

[Goran Klenkar]

Thank you both for your solutions.

Actually both suggestions worked.

Removing DAQmx start worked. However, since I am using multi-functional DAQ (AO and AI with triggering) it feels better to have the DAQmx still there. Especially as the LV example code for the same thing has it and says it is meant for arming the two units before activation/triggering.

Using a waveform works as well. But I do not understand why 1D DBL does not (2D DBL works on the other hand).

Anyway, thank you!