What Clock Can I Use as Reference Clock in Desktop Execution Node ?

Updated Oct 31, 2023

Reported In


  • PXIe-7976
  • AT-1212


  • LabVIEW
  • LabVIEW FPGA Module
  • LabVIEW Real-Time Module

Issue Details

I am using a PXIe-7976R (NI FlexRIO™ FPGA Module for PXI Express) and a AT-1212 (Signal Generator Adapter Module for FlexRIO). I would like to simulate my FPGA VI using the Desktop Execution Node. Within the Configuration Dialog Box that opens when placing the Node on the diagram, I need to specify to Reference Clock. I would like to select the IoModClipClock0 (an internal clock from AT-1212 module) as the reference clock. However, the only available clock in the scrolling menu is the 40 MHz Onboard Clock.


In simulation mode, the only clocks available as reference clocks are the FPGA high level clock and clocks derived from it. When running in simulation mode, only certain IOs from the FPGA are acessible and the IOs of the CLIP of the AT-1212 module are not part of them.

If your clock IoModClipClock0 is running at 156 Mhz, the solution is to create a derived clock at the same frequency. You will then be able to select it as the Reference clock in the scrolling menu.