Can DAC0 and DAC1 run concurrently at different sample rates for the USB-6251

[retrovalve]

Is it possible to run the DACs for the USB-6251 multifunction DAQ at the same time, each running at different sample rates?

If so, what is the suggested method (i.e., is it possible to run two separate Tasks()?).

[BrowningG]

Hello retrovalve,

Thanks for contacting National Instruments. 

Since you referenced the digital to analog converter (DAC) for your USB 6251 M Series device, I am assuming that you would like to run multiple analog output tasks at the same time. 

The DAQmx driver only allows for one of each type of task to be run on a DAQ device at a time.  This means that you can have one analog input task and one analog output task running at the same time, but not two different analog output tasks. 

For each analog output task to have a different update rate there will need to be some manipulation of the waveform in software before it is output on the card.  The following screen shot shows one method of creating two output waveforms of the same frequency that update at different rates.  In this case, one waveform updates four times faster than the other.  This can be checked using an analog input test panel in Measurement and Automation Explorer. 

Please post back if you have any questions. 

Message Edited by BrowningG on 11-19-2007 02:35 PM