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