OPC and DCOM Configuration. Configuring the Windows 2008 and Windows 7 firewall for DCOM and OPC. Tutorial.
OPC and DCOM Configuration on Windows 2008 and Windows 7
3. Configuring the Windows 2008 and Windows 7 firewall for DCOM and OPC
The DCOM technology the OPC technology is based on uses reserved system port 135 for its work. For servers and clients to run normally, you should permit these connections in your firewall. If the client and the server are located on different computers, firewall configuration is required. Below you can see an example of configuring the standard firewall in Windows 2008. If the client and the server are used on one computer, there is no need to configure the firewall.
Fig. 11 Access to the computer or server management console
For Windows 7 users. To open the firewall management console, use "Start" - "Control Panel" - "System and Security" - "Windows Firewall" - "Advanced settings" or run it from the command line with the "wf.msc" command.
For Windows 2008 Server users. To open the firewall management console, you may use the "The server management console" or run it from the command line with the "wf.msc" command.
3.1 Permitting DCOM activity
By default, Windows blocks inbound connections from other computer. For OPC clients to be able to connect to OPC servers on this computer, enable the corresponding rule.
Fig. 12 Firewall rule properties
Fig. 13 Permitting DCOM activity
For Windows 7 users. If the "COM+ network access" or "DCOM" rule is not in the list, create two "Port" rules.
3.2 Creating rules for every OPC server
You need to permit activity for every OPC server running on this computer. Also, you should permit network activity for the OpcEnum system service that allows remote clients to receive the list of servers from this computer.
Below you can see an example of how to create a rule for OpcEnum. Rules for other applications are created in a similar way.
Fig. 14 Adding an individual rule
Fig. 15 Selecting the file
Fig. 16 Rule properties
Fig. 17 Active profiles
Fig. 18 Rule name
Fig. 19 Active rules
You should repeat these steps to create a rule for every OPC server.