After Installing 3rd Party VISA Software NI VISA No Longer Works

Updated Jun 6, 2018

Reported In

Software

  • Measurement & Automation Explorer (MAX)

Driver

  • NI-VISA

Operating System

  • Windows

Issue Details

I previously installed NI-VISA on my system, and I was able to identify and communicate successfully with my instruments in 32-bit NI MAX, LabVIEW, or other development environment. I then installed another vendor's version of VISA, such as TekVISA or Keysight VISA. Now I can no longer identify or communicate with my COM ports or VISA instruments. Why is this occurring, and how can I resolve it?  

An error like the following may appear in NI-MAX:

MAX is unable to create a visa resource on this computer.

Solution

Only one 32-bit VISA implementation can be configured as primary on a system at a given time. This primary VISA acts as the core VISA library of the system.

In the case described above, NI-VISA is initially installed as primary and is then changed to secondary when the second VISA implementation is installed.

Reinstalling the appropriate NI-VISA software can reset the proper implementation scenario.

If the NI-VISA reinstall is not successful then you can reset NI-VISA as primary by following the steps below:

Verifying Which VISA Implementation Is Primary
First, verify that NI-VISA is not currently installed as primary on your system by following these steps:
  1. Navigate to the appropriate directory below based on the bitness of your OS and locate visa32.dll:
    • 32-bit systems: C:\WINDOWS\system32
    • 64-bit systems: C:\WINDOWS\sysWOW64
  2. Right-click on visa32.dll and select Properties.
  3. Find the copyright information:
  • On Windows Vista/7/8/10: Navigate to the Details tab:
  • On Windows XP: Navigate to the Version tab:

If the copyright information states National Instruments, then NI-VISA is set to be the primary VISA on your system. If another company is stated, then follow the steps below to make NI-VISA primary.

Setting NI-VISA as Primary
  1. Navigate to the appropriate directory below based on the bitness of your OS and locate visa32.dll:
    • 32-bit systems: C:\WINDOWS\system32
    • 64-bit systems: C:\WINDOWS\sysWOW64
  2. Rename visa32.dll to an alternate name, such as visa32.dll.bak.
  3. Repair the NI-VISA Runtime, by re-installing it according to our guide How Do I Uninstall or Repair National Instruments Software?
  4. Reboot your computer.

Additional Information

The reason that you must rename visa32.dll in step 2 is that repairing the NI-VISA installation will not automatically overwrite this file. The file will only be overwritten in the event that a newer version of visa32.dll is attempting to be installed, which is not the case when repairing previously installed software.

Note: Some 32-bit VISA implementations support being installed as secondary, which allows them to be installed side-by-side with 32-bit NI-VISA. For more information, see the Related Links below or contact the vendor.

Note: The primary and secondary VISA designations apply only to 32-bit implementations of VISA. Multiple 64-bit implementations of VISA can be installed to a system without running into this problem.

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