Hello Brian,
You are correct. Rather than exporting your trigger to an external PFI output, you can export the signal to the PXI trigger backplane using niHSDIO_ExportSignal and selecting any of the available PXI trigger lines. This function is used to route signals (clocks, triggers, and events) to the output terminal you specify. The available lines are NIHSDIO_VAL_PXI_TRIG0_STR to NIHSDIO_VAL_PXI_TRIG6_STR.
More information about niHSDIO_ExportSignal and the PXI trigger backplane lines can be located by refering to the NI Digital Waveform Generator/Analyzer Help and searching niHSDIO_ExportSignal. You can navigate to this resource by selecting Start » All Programs » National Instruments » NI-HSDIO » NI Digital Waveform Generator/Analyzer Help.
Typically, the data, clock, and start triggers are sent simultaneously from the transmitter/HSDIO generation to the DUT and then to the reciever/HSDIO aquisition. This is particularly important for synchronization regarding round trip delay (RTD). Since your implementation uses internal lines that exhibit less signal propogation, the system needs to simulate the round trip delay in hardware. RTD is further explained in NI Digital Waveform Generator/Analyzer Help and by searching Eliminating Round Trip Delay. Another useful resource is a C example called RoundTripDelayElimination. You can find the example by navigating to \National Instruments\NI-HSDIO\examples\c\Measurements\RoundTripDelayElimination.
If you decide to use this example, you must first know your total round trip delay. You can determine this by looping various delay values and confirming if that delay is acceptable for your system. Once known, you can set the Data Active Internal Route Delay property or the NIHSDIO_ATTR_DATA_ACTIVE_INTERNAL_ROUTE_DELAY attribute to that number of clock cycles. Then set the Data Position Delay property or the NIHSDIO_ATTR_DATA_POSITION_DELAY attribute to the desired fractional delay. I hope this is helpful.
Regards,
Roman Sandoval | National Instruments | RF Systems Engineer
