Hi, I wanted to understand the benefit of time while loop in data acquisition in RT. If I am acquiring an analog input with sampling rate of 1Ksps and reading 1000 samples per channel, I know that the loop will take 1 sec for execution. In such cases what will be the importance of timed while loop. In the image below, what extra benefit will I get by using TWL? Being data driven, the normal while loop will anyway complete the task of acquisition in 1 sec. Will TWL not consume more processor resources.

I'm assuming that your tasks use a hw sample clock to achieve 1 kHz sampling. I further suppose that you want your 7 tasks to start and remain in sync, both in terms of sampling and also in terms of data transfer. If so, I think you'll be much better off choosing a fixed # of samples to request from DAQmx Read and then iterating with a regular While Loop. Fixed-size data structures are generally a good idea in RT and it may be helpful over on the host side too. Methods that use Timed Loops will be at risk either of timing overconstraint (as I described earlier) or variable-sized packets. Either would affect the correlation of the data you transfer from the 7 independent tasks & loops. You'll still need to take some care to make the hardware-level sampling for those 7 tasks both start and remain in sync. That's more of a general DAQmx thing though, separate from Loop type and RT concerns. -Kevin P

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Timed while loop vs normal while loop in RT for DAQmx

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Thanks mcduff for the explanations.

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Timed while loop vs normal while loop in RT for DAQmx

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