"Write Not Supported" Error When Writing to Opc Server From VBAI

Updated Dec 18, 2023

Reported In


  • CVS-1459


  • Vision Builder for Automated Inspection 2019
  • LabVIEW OPC UA Toolkit

Issue Details

When I try to configure an OPC UA Inspection Step to perform a Read operation on desired PLC variables, it deploys successfully. However, when I instead configure a Write function to write information back to the PLC, the inspections step returns the error WriteNotSupported.

How can I resolve this error?


This issue is a known bug (895068), that a fix was implemented for in VBAI 2019 and later. 
The fix is not enabled by default, and can be enabled by placing the correct token in the .ini file. 

Follow the steps below to implement this fix:

  • Open the Vision Builder.ini file.
    • On Windows, this is located in C:\ProgramData\National Instruments\Vision Builder AI\20xx (where xx represents the software version number).
    • On real-time (RT) systems, this is located in etc\natinst\vbai
  • Underneath the [Settings] section of the .ini file, add the following line:
    • Use_OPCUA_MultiWrite_API = true
Note: If a RT target is being used, the .ini file must be modified on both Windows and the RT target.