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02/24/2014
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This is not a simple DCOM error.
My OPC DA Server is written by my organisation. It was developed from the OPC Foundation specimen OPC DA Server. There is some C++ code to handle the DCOM stuff and some C# code to handle the item names and values. I have the OPC DA Server running locally under DomainA\AccountA. The error does not occur when I'm logged in as DomainA\AccountA, but it does occur when I'm logged in as DomainA\AccountB. I know this is not a simple DCOM error because the test client does connect to a different OPC DA Server, written purely in C++, also running under the domainA\AccountA. I'm thinking it must be an Access Denied between the C++ code and the C# code inside the OPC Server.
Any suggestion about where the Access Denied error is coming from or how I can find out?
Hello Richard,
The "access denied" message certainly seems like this is DCOM related, unfortunately.
I don't think C# vs. C++ is a barrier since both are merely making calls into the COM framework; it's COM that is hitting the wall.
So, in your summary you mention "DomainA"; is this an actual Windows domain? Domains usually help.
I think you need to analyze the DCOM security, unfortunately. Check each user and group that has access to your Server, and then compare the membership of your two users. Some other places to consider might include file permissions (doubtful) and actual user-authentication within the server itself (assumes COM/DCOM has permitted the connection).
These problems are always tough.
02/24/2014
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Thanks Nathan,
You were right. I needed to set the user under which the OPC Server was running in the Default Access Permissions. I was fooled because the other OPC Server that did work had had it's user changed but it had not been restarted. Hence it was running under a different user which did have Default Access Permissions. I've been working with OPC & DCOM for over 10 years, but I still get fooled!
Richard
11/17/2016
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Hi Nathan,
I added the permission to the active user but when i tried to add the group to the connected server in Asynchronous way it is throwing this error. it works fine for Synchronous connection.
SIMATC2.1.ATC6AHR caused COM/OPC error 0x80010105 on IConnectionPoint.Advise()
Error string: Vendor Error string
Additional: Could not establish data callback connection on group 'grp1'
Interface address is 0x006B5834
Vendor detail: *********
What could be the issue.?
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