Troubleshooting – OPC UA

OPC UA Server Connection Error
Below are some helpful troubleshooting steps to resolve connection errors with OPC UA server.
Bad Data Quality

Server Url

The Server Url under Configure-Drivers must be specified correctly to then browse for the available Security Profiles.
Configure Drivers
OPC UA Server Url
Refer to the OPC UA server vendors documentation for the correct endpoint of the server. Once the Server Url is correctly set use the Browse button to select the Security Profile.

Certificate Authentication

If the OPC UA Server's authentication certificate is rejected it will be placed in C:\ProgramData\OpenAutomationSoftware\pki\rejected\certs on Windows or the pki\rejected\certs sub-directory where the OAS Engine is located on Linux.  To resolve and move the OPC UA Server's certificate file in the rejected\certs directory to trusted\certs.

User Authentication

If the OPC UA Server requires a user name and password to validate the connection enable User Security under Configure-Drivers and specify the Username and Password that is required by the OPC UA Server.
Configure Drivers
OPC UA Username

System Errors

Select Configure-System Errors and expand any OPC UA or Driver Interface error to see the details of the error.
Menu Configure System Errors
The information provided can often help you determine the cause of communication failures.
The history of all systems errors can be found in the OAS Error Log specified under Configure-Options-System Logging.
Menu Configure Options
Error Log Path

Log OPC UA Communications

You can enable the OPC UA transaction logging under Configure-Options-System Logging to track all interface calls to the OPC UA server.
Menu Configure Options
OPC UA Transaction Logging
Specify the location of where the communication logs will be saved with the property Transaction Log Path further down in System Logging.
Transaction Log Path
There will be multiple files generated with the opc-ua within the file name and also the base OAS Transactions file.

UA Expert

The UA Expert program is a good test application to communicate to OPC UA server to verify the server can be interfaced with. You can download UA Expert from
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