OPC Errors with XP SP2 DCOM

FAQ Question

I’ve been using OPC clients and servers with my IGSS installation on a Windows XP platform without any problems until now. However, after installing Service Pack 2, my OPC communication no longer functions properly. How do I solve this problem?


The Microsoft Windows XP Service Pack 2 has most likely been installed on the computers running the IGSS application. The SP2 software includes new security software, which impacts both the XP firewall and the DCOM module.

Download the OPC Foundation PDF file below and carefully follow the configuration instructions contained herein and the problems experienced with OPC communication should be resolved.

The most important thing to remember is that the user on the machine running the OPC client has to be authenticated on the machine running the OPC server, the best way to work around this is having the same user on both machines, this is not a problem in a domain enviroment, but when using workgroups you have to manually add the same user on both machines.

Using an OPC tunnel, or using a IGSS server/client setup as a tunnel to the OPC client machine is another way to work around DCOM security.

Begin problem solving with turning off firewalls and DEP (Data Execution Prevention), since windows sometimes block OPC traffic or prevents OPC servers/clients from running.

If this didn’t solve your problem check DCOM security by following the instructions in the whitepaper. 


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