The OPC Client connection to third party OPC Servers runs in a Windows Service called OPC Systems Data Service. By default this Windows Service runs under the System account. Connecting to other OPC Servers on the same PC that also run under the System account is easy.
Some OPC Servers cannot run as a Windows Service, so you may need to set the OPC Systems Data Service to run under the desktop user account so that the operating system allows the connection.
The OPC Systems Data Service can be configured to Logon as a Local System account or a User account. To correctly launch OPC Servers in the same window space it is recommended to set the OPC Systems Data Service to Logon with the User Account of the logged on user. Use the Service Control Manager to modify the service’s Logon Account.
If you are receiving bad data quality from the OPC Server it is most likely due to a security logon restriction in the operating system. To correct this it is recommend to set the OPC Systems Data Service LogOn to a valid user account.
View the following section on the Service Control Manager or the following video on how to set the OPC Systems Data Service Logon.
If the OPC Server is running as a Service you can often leave the Service LogOn to the Local System account, but check the box for “allow service to interact with desktop” if DCOM security is restricting the connection.
Refer to the Troubleshooting-OPC Connection section in this help file or the following video to resolve all OPC connection issues.