Troubleshooting VeriStand Custom Device Run-Time Errors

Updated Oct 31, 2019

Reported In


  • VeriStand
  • VeriStand Custom Devices

Issue Details

My VeriStand project uses one or more custom devices and is throwing a run-time error that I cannot seem to easily resolve or narrow down on my own. What resources are available to help me troubleshoot these run-time errors?


  • Verify that the error is actually caused by the custom device by observing whether the error persists after removing the custom device from the system definition. 
  • Sprinkle the NI VeriStand – Print Debug String VI throughout the custom device code to print useful strings to the console to help you debug and trace the execution of the VI.
  • Use the Console Viewer to view any error information and determine the VeriStand engine state.
  • If possible, simplify the custom device to the smallest reproducible case to isolate the source of the error.
  • If possible, move the main custom device logic to a new Real-Time VI and test the functionality outside of VeriStand.

Additional Information

If you are experiencing custom device configuration or deployment errors, please see the articles in the Related Links section below.

If you can verify a run-time error or unexpected behavior comes from the custom device, then the source of the problem is from the RT Driver VI. This would include the Execute Model case of an inline model custom device, the Read Data from Hardware and Write Data to Hardware cases of an inline hardware custom device, and the contents of the while loop in an asynchronous custom device.

Custom device development can be challenging. Refer to the Creating Custom Devices - VeriStand Help landing page to learn more about types of custom devices, what it takes to create one, how to access when to need one, and the process of, planning, implementing, debugging, and building one from scratch.

For a comprehensive, in-depth, older (but still useful) guide into VeriStand custom device development, please review the NI VeriStand Custom Device Developer’s Guide.