How can you get OPC Server data through a firewall?

It is possible to configure a system to allow OPC communication to pass through a firewall.  This requires that you open a port for DCOM communication and allow exceptions for each application.  On the PC running the OPC client: Allow exceptions for DCOM communication, which occurs on TCP port 135. You must also provide exceptions for any OPC Client application.  On the PC running the OPC Server: You must also allow exceptions for DCOM communication, which occurs on TCP port 135.  Then provide exceptions for both the OPC Server and OpcEnum.

 

Another alternative would be to eliminate DCOM altogether by using OPC Tunneller.  This application allows OPC communication between any OPC client and server to be passed via TCP/IP.  OPC Tunneller also provides extra security and encryption.