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Triggering acquisition in custom device syncronised with the PCL



I'm looking to create a custom device that will acquirea finite amount of data for a set time from a DAQ module on a PXI triggered by an input from VeriStand (most likely using DAQmx functions). The acquisition time and length will be set as configurations by the operator before deployment in the system definition file.


Initially, I created a DAQmx asynchronous custom device but then realised my trigger isn't actually synchronised with the PCL (and I require it to be).


My current thoughts are to build an inline-asynchronous custom device. My thought process is that I need the DAQmx functions and acquisition on the asynchronous side since I do not want this to hold up my PCL (which is running around 20-25kHz) and log the data to TDMS. But I still have the challenge of synchronising the start of the acquisition and trigger with the PCL.


Does anyone have any suggestions of implementation to achieve that level of synchronisation? Am I even heading in the right direction?


Any help would be greatly appreciated.

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First of all apologies for the late reply. I needed to get my head around VeriStand and PCL Synchronisation.


To give you support on this:

- Which PXI module are you using?

- Do you have any PXI timing module available for hardware synchronisation?


I am not 100% sure at the moment, but I think that if hardware level synchronization is required, you must synchronize VeriStand Engine and DAQ's hardware timing loop. And to do so, you would need to use timing module such as NI PXI-6683 and PXI-6683H in order to achieve this synchronization.


However, I will look into this and give you an update.





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Apologies in my delayed response. For some reason the website doesn't let me reply through my work laptop and I'm having to do this on my phone!


I'm using a PXIe-6366 and have not got any hardware synchronisation.


I'm looking to synchronise my software trigger which is "in the loop" and am looking to develop an inline-async custom device to do so. Though I'm not sure how I can trigger the acquisition which I am looking to do in the asynchronous side of the custom device.


Hope I've explained myself well... if not, I'll try again!



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To better understand your application, why is the synchronisation of the trigger with the PCL required?





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Hi Rob,


I would like to trigger a digital acquisition of multiple channels from a custom device at 1MHz. I need to trigger the test synchronised with the start of a test case, so was thinking of adding a Boolean software trigger to be set inline with the PCL that would start the acquisition (on the asynchronous side of the custom device as well as the logging).

Would you say this is the right approach of what I am trying to achieve?


Any support would be greatly appreciated.



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I have found this article here which might help us to get started with the synchronization of the asynchronous custom device with the PCL:


Let me know if this is helpful.





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