Speed of single-channel pattern match trigger vs. edge trigger on PXI-6562

[Artybear]

I think my question boils down to this: what does the edge-trigger feature provide that is not provided by the pattern-match-trigger?

As far as I can tell, the only differnece on the PXI-6562 is that the edge-trigger has its own dedicated pins (PFI pins and RSTI pins) on which to sense a trigger, whereas the pattern-match-trigger senses a rising or falling edge on a regular input pin.

Is there a performance difference (such as the re-arm time)?

Are both trigger types synchronous with the sample clock for dynamic acquisition?

About my application:

I am acquiring a signal off of an SPI bus, triggering on the CS line. I start acquiring data when the CS line goes low, and stop when the CS line goes high. Since I acquire the CS data on a regular input, it makes sense to me trigger on a pattern match for only that channel. I am curious if there is any advantage to connecting a PFI pin to my CS input so that I may trigger using the digital edge type.

Thanks in advance,

Arthur

[Timothy_S · Accepted solution]

Arthur,

There won't be any difference in regards to performance for using a digital versus a pattern match trigger type. The specifications for rearm time will reference the trigger type (Start, Reference, etc) in samples for rearm, and there won't be any difference with the performance when using a digital edge on a Trigger line/PFI line and a pattern match used on the input signal. Changing the source of the trigger itself will not change the hardware performance that occurs after the trigger is received. This behavior would sync with the acquisition clocks regardless of the input source. We are simply looking at differing sources for the board to look for a given trigger.