How to calculate a PXI system's overall propagation delay

Updated May 3, 2018

Reported In


  • PXI Chassis
  • MXI Cable
  • PXI Controller

Operating System

  • NI Linux Real-Time
  • Windows

Issue Details

How can I quantify the delay that I am seeing within my PXI system from when I manually trigger the acquisition process on the User Interface until I am able to see the acquired data on my monitor?


The system delay that you will experience is extremely dependent upon your system's configuration that you have setup. Everything from the PXI Chassis, PXI Controller/MXI interface, and your computer's operating system down to the MXI cable material/length will impact your system's propagation delay. 

​To quantify this propagation delay you can add up the calibrated timing delays from your NI device's specification sheets as well as your computer's operating system to provide you with a "worst case scenario" but many factors along the way can impact this delay significantly.

To provide yourself with the lowest possible timing delays you can rearrange the cards on your PXI chassis (per the PXI Express FAQ document in the related links below) as well as use a deterministic operating system (i.e. a Real-Time OS) to reduce the number of unknown variables created by a non-deterministic operating system. 


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