multiple tasks in daqmx

[pawhan11]

Hello,

I have project where I use 2 AO and 4DO to generate some predefined signals and  2 AI to acquire response. When testing only one sensor this works fine. In future I will have to test aditional sensor concurrently to the first one. User can start fitst and secould slot whenever he wants.

I can't create 2 AO tasks at the same time using only one PCIe card. I can;t combine all AO from slot 1 and slot 2 into one task becaus test on slot 1 has diffrent frequency (defined by user when other slot i running), amplitude and is started by user at  different time.

Do I need to buy additional PCIe card to run test on slot 2?

[James.M]

If you want to run at seperate sample rates, you'll need seperate cards because that's the only way the hardware timing can work.

A workaround could be for you to sample at a rate faster, or equal to, the fastest that you would want to sample either slot and then average down to a lower sample rate based on your needs.

Example:

Sample all channels at 1kHz.

Slot 1 uses channels 0-7 at 1kHz, Slot 2 uses channels 8-15 at 2Hz.

The application is continuously using the data for slot 1 at 1kHz and throwing away the extra channels. Slot 2 picks up the extra channels when needed and down-samples to desired data set.

[crossrulz]

This might be a good place for cDAQ.  Your main problem here is the different sample clocks.  Once the Analog Output clock is being used by 1 task, another AO task cannot use it.  So you will need to use another card.

[pawel.ostrogorski]

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[pawhan11]

Thanks for reply. In my project signals that I generate have low frequencies - up to 1kHz

With one slot I worked with finite samples like that:

Here are my 2 signals, first one has 1kHz, secound has 1 Hz. I can say that maximum frequency for signals will be 1kHz,then logical step is to resample all signals to that frequency

And then I need to generate in continious mode without regeneration? I will need to move this large signals into buffer in smaller parts?

I attach example how this concept looks now with some questions

When using cDAQ I can run up to 3 concurrent AO tasks?

http://digital.ni.com/public.nsf/allkb/5E0B829E50ADE1BC86257AC50062B2D2

Thanks in advice.

[pawhan11]

Cant; edit previous post. I am wondering if I can do read and write in one loop. It would be much simpler and effect is the same