Question

We have an OPC Server running on windows server 2003. I am using an OPC client from a remote machine running on Windows Server 2008.

From the OPC Server node, I can ping the Client node. However I am not able to telnet ( I tried only port 135 which is for DCOM communication).

Any other machine can telnet the client machien i.e. Windows Server 2008.

I see on OPC Server, the port 135 is added.

One more thing, the tracert doesn’t fully show all the hops from OPC Server to OPC Client.

I can telnet from OPC Client to OPC Server on port 135.

Do you think port 135 communication is blocked when the telnet packet routes from OPC Server to OPC Client ?

Please reply . Its driving me crazy. DCOM headache !!

Answer 1

There was a firewall problem. You always have to make sure port 135 is open on both the sides. Use telnet to verify port before dealing with DCOM issues.