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

Updated Oct 26, 2020

Reported In


  • CVS-1459


  • Vision Builder for Automated Inspection 2019

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. 

To enable the new code path that should fix this issue in VBAI 2019, add the following line in the [Settings] section of the Vision Builder.ini file on both the Windows and (if applicable), on the target side as well:

Use_OPCUA_MultiWrite_API = true

On Windows, the Vision Builder.ini file is located in C:\ProgramData\National Instruments\Vision Builder AI\2019

On the RT system, the Vision Builder.ini file is located in etc\natinst\vbai