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Dynamic Acq Harware Start Trigger

Hi Everyone,

I'm using a PXIe-6556 to capture digital signal. I'd  like to start capturing signal upon receiving a hardware start trigger in PFI0.

The PXIe-6556 works fine with this method when using the onboard clock but won't start capturing when I'm using an external clock via ClkIn as a source clock.


Is this a hardware limitation for PXIe-6556?




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Hello jeep,


That should work fine.  You can use an external clock and a PFI trigger.  Do you need to have your sample clock running and the session started before your external trigger event?  The PXIe-6556 does require a free running sample clock, and it needs to be operational to correctly sample triggers.


I hope that helps,


Jesse O. | National Instruments R&D
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Hi Jesse,

Before the start trigger, there is already a free running clock in ClkIn and the session has not yet started.



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