Continuous analog output ao daq

Hi! I'm working with a national instruments data acquisition USB 6211 with the aim of generating an analog signal during several hours. I work with SamplesOutputFcn event in order to introduce new samples into the engine each SamplesOutputFcnCount. The problem is that when 4.2929e+09 samples has been generated (at a SampleRate of 100000 S/s) the object stops outputting the signal when its status is still sending data.

Could anyone tell me if there is any limit in the number of samples that can be output per trigger with an analog output object?? I try to find it in the data acquisition toolbox's help without any success.

Thank you very much!

[Timothée]

Hi,

Had you finally found a solution? I have the same kind of problem

Answer 1

[Daniel Shub]

I have not used that card (or even the DAQ toolbox in a long time). It would not surprise me if the limit was 2^32. In fact

log2(4.2929e+09)

ans =

   31.9993

The limit is likely on the NI driver and not the DAQ toolbox. At 100 kHz, 2^32 samples is already 12 hours, how long do you need to go for? Can you lower the sample rate?

[Izaskun Azk]

I can't lower the sample rate.Anyway you can be right, it maybe is a limit of the NI driver.However, I can't find this information in any National Instrument's domument. I need to generate 16 hours of the signal, therefore I am thinking about doing them in 2 sessions of 8 hours.

Thank you!

Answer 2

[Sean de Wolski]

Use a timer function to repeatedly call the analog out trigger function.

doc timer

[Izaskun Azk]

If I do that, the signal will stop between one and the next trigger, am i wrong?

[Sean de Wolski]

No. Set your trigger period to be the same length as your sample rate/output so they align.

[Sean de Wolski]

(I haven't used the DAQ toolbox in a few years and I'm on a MAC which doesn't have it, sorry I can't be more specific.)

[Izaskun Azk]

I tried it, but you need to stop the running object to call the trigger function again, and I can't stop the generation of the signal.

Thank you!