Reserving and Releasing Trigger Lines for High-Speed Serial Modules

It's important that you reserve the trigger lines used by your high-speed serial module. Without the trigger lines reserved, two PXIe devices could try to drive the same trigger line in different applications, which could cause an application to fail, and, in some cases, cause damage to third-party PXIe devices.

You can use Measurement & Automation Explorer (MAX) or the host VI to reserve trigger lines.

If you download and run the FPGA VI interactively, configure the PXI triggers in MAX. MAX maintains the trigger reservation for the device even after you cycle power to the PXI chassis.

If you download and run the FPGA VI programmatically, reserve the trigger lines in the host VI. Use the Invoke Method function to reserve the trigger and to release the trigger reservation. LabVIEW releases the trigger reservation for the device automatically when you close the FPGA VI reference. You must run the host VI again to reserve the trigger.

Reserving and Releasing Trigger Lines Step-by-Step

Note To release trigger lines, select Unreserve PXI Trigger in step 5.
  1. Place the Open FPGA VI Reference function on the block diagram and configure it for the FPGA device and FPGA VI.
  2. Place the Invoke Method function on the block diagram.
  3. Wire the FPGA VI Reference Out output of the Open FPGA VI Reference function to the FPGA VI Reference In input of the Invoke Method function.
  4. Wire the error out output of the FPGA VI Reference function to the error in input of the Invoke Method function.
  5. Click the Invoke Method function and select Reserve PXI Trigger from the shortcut menu.
  6. Right-click the Trigger input and select Create»Constant. An enum constant is created to help you select the trigger.
    Note To reserve or release multiple trigger lines, repeat steps 2 through 6 for each trigger line you want to reserve or release, wiring the FPGA VI Reference Out output of the existing Invoke Method function to the FPGA VI Reference In input of the Invoke Method node that follows it.