A Primer to the OPC-COM Tunneler Module

Posted by David Schmidt, Last modified by Peggie Wong on 06/24/2015 02:22 PM

The OPC-COM Tunneler module eliminates many difficulties associated with establishing remote OPC-COM connections. The OPC-COM Tunneler module exposes OPC-COM connections to Ignition's OPC-UA server. The connections appear and behave as devices connected to Ignition's OPC-UA server. In this way, Ignition manages the OPC-COM connection in the context of the OPC-UA standard resulting easier access over the network, eliminating the need to establish remote DCOM connections, and incorporating the security benefits of the OPC-UA standard such as authentication and encryption. This module can be considered a "UA wrapper" for classic OPC servers.

A typical scenario may involve the following example. An integrator was installing Ignition at a customer site as part of a larger Ignition project. The project required the new Ignition server to connect to a remote OPC-COM server. The integrator was aware that establishing an OPC-COM to OPC-COM connection would have been difficult due to the onerous security configurations. Instead the integrator would have liked to establish an OPC-UA to OPC-UA connection between the servers. To accomplish this, the integrator installed an additional Ignition server on the remote server. The only Ignition modules installed on this remote server were the OPC-UA, OPC-COM, and OPC-COM Tunneler modules. The integrator established a local OPC-COM connection between the new Ignition server and the local OPC-COM server. By virtue of having installed the OPC-COM Tunneler, the module added a new type of device that exposed the local OPC-COM connection through Ignition's local OPC-UA server. The integrator then created a new device by selecting the OPC-COM Tunneler driver from the list of device options. The integrator then established an OPC-UA to OPC-UA connection between the two Ignition servers. The main Ignition server could then interact with the remote OPC-COM server through this OPC-UA connection.

The OPC-COM Tunneler assumes the following prerequisites are properly configured before the OPC-COM Tunneler can perform properly.

  • Ignition is installed at the main server and each server's firewalls are configured to allow traffic at the port Ignition will use to communicate with external OPC-UA servers. The port settings are located in the Ignition Gateway's Configuration tab, OPC-UA section under Settings.
  • Ignition is installed at the remote server. Ignition is licensed by the server therefore a different license key will ensure this installation of Ignition is appropriately licensed for its intended purpose.
  • The OPC-COM service at the remote server is connected to the Ignition service running on the remote server. In essence, the OPC-COM service is configured as a local OPC-COM service in Ignition.
  • The OPC-COM Tunneler module is installed on the remote server. 

The following picture shows the availibility of the OPC-COM Tunnel Driver as a new type of device availible for installation on the Igntion Gateway where the OPC-COM Tunneler module is installed.

The OPC-COM Tunneler is now ready for final integration. Create a new device in Ignition at the remote server. Select the OPC-COM Tunnel Driver option as a new device. It will expose the OPC-COM connection as a device inside Ignition's OPC-UA service.

The following picture demonstrates the OPC-COM Tunnel Driver as a connected device.

Finally, from the main server connect Ignition's OPC-UA service to Ignition's OPC-UA service running at the remote server. Verify the OPC-COM Tunneler is operating as intended by selecting Quick Client from the Configure tab of the Ignition Gateway on the main server.

This is a picture of the main Igntion server's quick client communicating with the remote Igntion server via OPC-UA connection. The remote Ignition server's local OPC-COM connection to a Kepware OPC server is exposed to the main Ignition server as a new device under the remote OPC-UA connection.

The OPC-COM Tunneller allows for many OPC-COM connections. Each connection will appear as a node item under the tunneled device.

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