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PXIe 6368 External trigger based Digitization


PXIe 6368 External trigger based Digitization


I want to  digitize 16 analog inputs of PXIe 6368 using external trigger pulse. As PXIe 6368 also has four analog outputs, is it possible to generate external trigger pulse from same PXIe card (using one of its DACs) while simultaneously using its ADCs in external trigger mode?


Note: I asked this question because i have used PCI 6123 card in external trigger mode and until it does not receive external trigger, it remains in waiting state.


Thanks & Regards

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Message 1 of 4

Re: PXIe 6368 External trigger based Digitization

First let's define terms for clarity.  Otherwise we might just talk past each other.


The NI terminology used by DAQmx would distinguish a trigger from a sample clock based on this:

- a task captures 1 sample for every sample clock active edge 

- a task captures 1 SET of samples for every trigger active edge


So are we really talking about an external trigger or is it an external sample clock?


Generally speaking, the DAC and ADC subsystems can operate independently such that the use of one doesn't particularly restrict the use of the other.   I'd have expected to be true even for older 6123, unless this was a long long ago usage with the old traditional NI-DAQ driver.  If one kind of task was in a wait mode, other tasks were restricted from access to the driver.



-Kevin P

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Message 2 of 4

Re: PXIe 6368 External trigger based Digitization

Thanks for help. we are talking about an "external trigger"  which initiates/starts digitization using on board clock and not an "external sample clock ".

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Re: PXIe 6368 External trigger based Digitization

I fully expect you *could* use an AO channel to generate a trigger pulse that drives your AI acquisition.  I think it'd probably be preferably to use a DO channel though.  Many of the DO output pins serve double duty as PFI pins that can be designated as trigger sources for the AI task.  That'll save you from the need to run any physical wiring.



-Kevin P

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