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I can't receive A&E events remotely, via the DCOM connection.

I am familiar with DCOM trickery and configured OPC DA many times, but this is not the case.

For instance, I've composed the proof-of-concept configuration consisting of two virtual machines with fresh WinXP SP3 installations with A&E enabled Matrikon OPC simulation server on the first virtual host and Matrikon OPC Explorer on the second virtual host. I've configured DCOM, so I can see the simulation server's OPC DA subset from the "client" host. But I don't receive any A&E Events from there. I can receive them if and only if I connect to the Simulation Server locally on the "server" host. On the client host, I get the COM error message instead (see attachment). the error message

AFAIR IConnectionPoint interface mentioned in the error trace is related to the COM events mechanism.

I suppose that OPC A&E uses COM events mechanism as transport layer. I am not sure though how these events is supposed to be delivered to the client side if client reside on the remote machine. IMO, the client machine should have a free RPC listener for receiving inbound asynchronous callbacks. Most likely, this raises some security issues and this potential security hole is blocked someway.

Can you please share some thoughts on this?

eglease
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Minor Threat
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  • Have you configured DCOM on the client computer as well? You must enable the server to call the client. – Jouni Aro Nov 09 '13 at 09:29
  • They are entirely symmetric. I've used the virtual machine cloning feature after configuring DCOM. The username and password is the same aswell. The only distinctions are the IP, MAC, and the host name. OPC DA is working as expected if I reverse their client and server roles. – Minor Threat Nov 09 '13 at 10:03
  • If you have tried by turning off all authentication in DCOM and it still doesn't work I would suggest that you contact Matrikon, maybe they are preventing it for some reason. – AndersK Nov 11 '13 at 07:15

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