Generate Trigger on PXI Backplane Programmatically

Updated May 24, 2018

Reported In

Hardware

  • PXI-1044
  • PXI Chassis

Software

  • LabVIEW

Driver

  • NI-Sync
  • NI-DAQmx
  • NI-VISA

Issue Details

  • I am using a PXI chassis. I need to synchronize multiple modules connected to the chassis using a common trigger source. Is it possible to generate a trigger through software, i.e. programmatically? How can I implement this?
 
  • I am migrating code from VXI to PXI and was able to programmatically trigger. Is this same feature possible in PXI?

Solution

It is not possible to generate a trigger on PXI Trigger bus programmatically. While you can reserve and route different trigger bus lines through NI-VISA driver, MAX, or with some drivers in LabVIEW, the idea of trying to set the trigger bus high or low cannot be implemented. The PXI Trigger bus is simply a bus used to route triggers through the backplane. However, there are other ways to get this desired feature depending on the hardware in your chassis:

Timing Cards:
  • If you have access to a timing card, we have examples to help accomplish this task. If you are using a signal-based timing card (for ex., PXI 6651/6652/6653, PXIe 6672/6674/6674T), than you can modify the Route Software Trigger LabVIEW shipping example.
 
  • If you are using a time-based timing card (for ex., PCI 1588, PXI 6682/6682H/6683/6683H), than you can modify the Generate Digital Pulse LabVIEW shipping example. As a note for the Generate Digital Pulse example, if you remove the time parameter going into the niSync Create Future Time Event than the VI defaults to sending it immediately.
DAQ Cards:
  • If you are using a DAQ or similar device, you will need to write to any given trigger line from one of the chassis slots with a card (for example a multifunction DAQ device), or provide an external trigger source to drive the line. 
There aren't any VISA commands to programmatically set the PXI trig lines high or low at any given time.

Additional Information

On VXI systems you would use VISA to programmatically send a trigger. The function that you used to do this on VXI systems is now used to reserve the PXI trig lines.

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