VXI-MXI-2 Locks Up or Freezes Upon Simultaneous VXI Register Calls

Updated May 3, 2018

Reported In


  • VXI-MXI-2
  • Chassis for VXI


  • NI-VXI 3.9

Issue Details

I have an application, program, or executable that calls register level functions on my VXI-MXI-2 card. It runs properly as a stand-alone application. However, once I create a second instance of this application, my programs begin to freeze or hang upon running. How can I properly run my applications in parallel and fix this issue?


This is a known issue, and using the attached DLL will help fix this issue. This patch lets the user perform messaged-based accesses and register-based block moves simultaneously. The message-based accesses supported by this patch are basic I/O functions (viRead, viWrite, and its variants) and formatted I/O functions (viScanf, viPrintf, and its variants). This patch applies to NI-VXI 3.9 software. Please refer to the readme in the attached .zip file for installation instructions.

Additional Information

This DLL is not an official patch and does not need to be used unless you want this specific functionality. Please refer to the attached readme for more information.


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