Unable to browse network for available OPC DA servers on Windows Server 2019 but can connect to OPC DA servers if manually specified

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Has anyone seen anything on Windows Server 2019 that would prevent browsing the network in a Active Directory domain environment to find available OPC servers on remote hosts when all other OPC communications seem to be functioning normally and file share browsing seems to also be functioning?

There is something I'm missing here, but I cannot find it. Since the core OPC functions are working, tools like OPC Expert are not showing any errors and guides for DCOM settings from OSIsoft, KEPware, and OSI Institute are all being used to no avail. None of the DCOM settings seem to be addressing the CLSID network browsing. If a client has the ability to supply a remote host and query that host, the OPC services enumeration works just fine. The problem is that we are attempting to use clients that do not have any features to manually define the servers and solely relies on the network browsing functions.

Please tell me someone else has seen this behavior. I suspect that it is some network security feature of Windows Server 2019, but I can't find any documentation that points to what might be causing this function to fail. Worse, the function is completing normally, but with zero results, so I don't even have error messages to track the issue down with.

windows-server-2019 opc
1 Answers

It really depends on the application you are using. There are many ways for an OPC Client to find the remote OPC Server. Most clients will use a combination of the folowing:

OPCEnum. In particular the heavy lifting is done using EnumClassesOfCategories which is part of Component categories Manager. Does not crawl through registry.

GetOPCServers(). This is a method is available as part of an interface called IOPCAutoServer which comes from the OPC foundation itself (via OPCDAAuto.dll)

CLSIDFromProgID() first to get the CLSID and then does the CoCreateInstanceEx(). When CLSIDFromProgID() fails, it falls back to using OPCEnum to list all OPC servers before making a connection.

That means that you would first need to find out what your client application is using to list the OPC Servers. Then, on the Windows Security side of things, depending on the OS version of both nodes, you may need to disable Simple File Sharing mode (that is the case for Windows XP and older)

If it uses OPCEnum, you will need to configure DCOM for OPCEnum as well, which is the recommended method to list remote OPC Servers. If the application only supports remote registry lookup to find the OPC Server, then you will need to grant access to the account connecting from the client to the Server

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