Question

I need to realize OPC server, on Windows XP. I download OPC library, and OPC client (application not library). I realize my OPC server, when i use client on my machine all runs normally. But when i connect from remote computer i do not see my server. I understand that the technology dkom potentially dangerous. I get this manual, and did everything on it, but nothing changed. I disable my windows firewall, add 135 port in windowds firewall exception. In dcomcnfg grants local and remote access to “anonymous” and “all” groups, grants local and remote launch & activation to “administrators” and “all” groups. And nothing changed, i did not give the right of my DCOM component because i thought the following: i get list of servers not work with them. In my microsoft network no domain and active directory, can i achieve the desired result in this case?

Answer 1

There’s a number of things which can go wrong with OPC DA over DCOM. From the top of my head, you could try the following:

• Check if OPCEnum service is running on the server computer. This service provides the list of OPC servers on to the potential clients. It’s part of the OPC foundation redistributable.
• Make sure that whatever dcomcnfg changes you applied, they are done both on the server and client computer.
• If you’re using only local users, try creating a dedicated user for OPC access on both server and client computer, e.g. call him “opc”. Then grant all the rights to this user in “COM security” section of dcomcnfg. Run both the server and client as “opc”. Make sure the local users authenticate as themselves (see “Security options” in local policies).
• If all else fails, a workaround can be to deploy the server on the client computer, register it, then remove it. Worked for me once.