Synchronous Digital and analog I/O daqmx

I have 2 PCI - 6254 s in a linux machine and I am trying to sync the analog input (ai0:1) with the incoming digital data (port0) data.  I fed a sample

clock to Dev1/PFI0.  (I currently use a little the e/s from one of the boards installed) Somehow, I can't align the analog and digital data.  I know because I use digital data to reverse the polarity of the analogue data still incoming digital data (print buffer) are correlated with what is happening in the name of the analog data.

If I use the AI/sampleClock internal as the common Terminal analog and digital data seems functional and are repeatable.

Thanks in advance for your suggestions.

The problem is that the two tasks are not guaranteed to start at the same time because they are not sharing a common start trigger.  In other words, there will probably be a nondeterministic number of samples of phase difference between the two acquisitions.  Unfortunately, the digital I/o on this forum does not support any which trigger feature you can not use just a common starting trigger.  Probably the best thing to do in light of what you have described so far is to use PFI0 as the AI sample clock and change the clock for your digital/Dev1/I/SampleClock task.  You must then make sure you start your digital task before the task to HAVE it.  This should actually slave of your digital clock to the clock of the analog task and actually start both at the same time.  Given that each task physically uses a different signal than its clock (PFI0 vs an exported version of AI/SampleClock), there will be a small amount of latency between the two.  However, this should be the order of tens of microseconds, so I do not have a significant impact.  Also, as the digital task is actually controlled by the clock of the analog task, it will actually start and stop the analog task you called stop task on the digital task.  I hope that this will not be a problem for your application.

Tags: NI Hardware

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