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Sync high speed digitizer to CompactDAQ chassis


I'm taking measurements with a high speed digitizer (NI PCI-5114) and tracking how they change in real time using the timing information (absoluteInitialX from wfm info) from the card.

I'm also taking data from a second device which sends trigger signals to a compactDAQ chassis (NI 9402 plugged into a NI cDAQ 9174).  This is used to get timing info from the second device.


Now I would like to sync up the two data sets,  I am only taking relative time data (i.e. time since the start of the test) and I'm willing to trust that the clocks on either device are accurate so I just need one point of reference (i.e. a starting time)


My plan was to setup the NI cDAQ 9174 to output a pulse, when the clock is reset to 0, through one of the unused bnc connections of the NI 9402 and connect this to the external trigger of the NI PCI-5114.  Thereby reading the time this pulse occurred from the high speed digitizer, which would be my offset between the two devices.


The problem is I have very little experience with the NI cDAQ 9174 and am not sure how to set this up (or if it is even possible).  Also, I'm always open to more simple/elegant solutions as to how to sync these two devices.



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Hello GollumGTH, 


If I understood correctly what you want to do is to synchronize both devices so that they use the same clock as a base correct?

if this is the case you can use the export signal vi to export the clock of either device through a PFI line and use that PFI line as the clock on your Timing Vi when doing the acquisition.


there are synchronization examples for multidevice in LabVIEW that you can check.


Go to help»Find Examples»Hardware input and output»DAQmx»Synchronization»multi-Device





Luis A.

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After talking to NI tech support I'm going to trigger my counter with an arm trigger similarly to the second example in this post:


I can then feed this trigger signal into my high speed digitizer to get the timing info I need to sync the two devices.


It forces me to use two additional ports on my CompactDAQ chassis (one to produce the trigger pulse, another to read it) but I could find no way around this. (To be clear I would have preferred to only use only one port to output the trigger signal to the high speed digitizer)

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