Does OPC Expert Need to Be Installed on Primary and Secondary Servers?

Does OPC Expert need to be installed on both the primary and secondary OPC server machines to support redundancy?

The answer depends on whether you are using OPC Expert with or without tunneling. In a direct connection setup, OPC Expert runs only on the machine where your application resides and connects to the primary and standby OPC servers over the network using standard OPC protocols. In a tunneling setup, OPC Expert also runs on the primary and secondary server machines to handle the tunnel endpoints. In neither case does OPC Expert require a traditional installation: it runs from a single executable file and does not modify the Windows Registry.

Direct Connection Configuration

When the OPC servers on the primary and secondary machines are accessible directly over the network via OPC DA or OPC UA, OPC Expert does not need to run on those machines. It runs on the machine where your application is located and reaches out to both servers using standard OPC protocols. This is functionally identical to any other OPC client connection, except that OPC Expert manages two connections simultaneously and handles the failover logic between them.

In this configuration, the only machine running OPC Expert is the one hosting your application or acting as the data consumer. The primary and secondary OPC server machines continue to operate exactly as they did before.

Tunneling Configuration

When OPC Expert’s built-in tunneling feature is used, a copy of OPC Expert is placed on each of the primary and secondary server machines as well. In this setup, the instance of OPC Expert on each server machine acts as a tunnel endpoint, exposing the local OPC server data over a single TCP port. The instance on the application machine connects to those tunnel endpoints rather than connecting to the OPC servers directly via DCOM or UA.

This architecture is particularly useful in environments where DCOM configuration is restricted, firewall rules limit port access, or the network topology makes direct OPC connections unreliable. Because OPC Expert requires no installation and does not touch the Windows Registry, placing it on the server machines carries no risk to existing software or configurations on those machines.

Running as a Windows Service on Each Machine

In the tunneling configuration demonstrated in the webinar, OPC Expert on each server machine is configured to run as a Windows service. This ensures it starts automatically with the operating system and continues running without requiring a user to be logged in. The setup is done through a right-click option in the OPC Expert interface, and the service runs under the system account. Once running as a service, the graphical interface is no longer needed on those machines and can be closed.

Related Tools

OPC Redundancy is the feature within OPC Expert that manages the failover logic between primary and standby data sources, regardless of whether the connection is direct or tunneled.

OPC Tunneler is the built-in component that handles secure, single-port communication between OPC Expert instances across a network, replacing the need for DCOM configuration and enabling reliable connections through firewalls and restrictive network environments.

Conclusion

OPC Expert does not require installation on the primary and secondary server machines in a direct connection redundancy setup. When tunneling is used, a copy of OPC Expert runs on each server machine as a tunnel endpoint, but it requires no system installation and carries no risk to existing configurations. Either approach is configured through OPC Expert’s visual interface and can be set to run automatically as a Windows service.