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DCOM is the Distributed form of COM. An important thing to remember is that
an OPC Server does not normally know that the OPC client is attempting to
connect to via DCOM. With that in mind KEPServerEX has little to do with
problems that result from DCOM settings. This does mean that KEPServerEX
can't be placed in a DCOM state that prevents the user from connecting.
We recommend turning off DCOM security for your initial remote
connection. If you are using version 4.30.146 or newer of KEPServerEX
you can turn off DCOM from the OPC Settings Tab from the Tools|Options
selection of the server menu.
If you are unable to make a remote connection the most common DCOM
problems are as follows:
- The user has changed the default security settings of the DCOM
configuration. The easiest way to get a DCOM connection working is to
set the default security of the users system to allow access for both
the "System" user and the "Everyone".
- The other DCOM setting that must be correct is Launching Permissions.
This selection must also include the "System" and "Everyone" settings
and they must have full access.
- The Default Configuration Permissions must also contain the "System"
user and the "Everyone" user and they must have full control.
Now this means that the user's PC is wide open for COM objects,
but this is the best starting point when trying to fix DCOM settings.
Once the user has the OPC client connected to KEPServerEX and working
then they can back off the security to tighten the access levels.
The other DCOM setting that can have some impact on the operation
of an OPC client is the Identity setting for KEPServerEX. Normally
this setting is set to "Interactive User". In some cases the OPC
client application launches KEPServerEX from a service or system
level account. When this occurs it may be necessary to set Identity
of KEPServerEX to "Launching User".
For more information or help setting your DCOM settings, Download our DCOM Configuration Guide (PDF).
Windows XP SP2 Viewlet
DCOM FAQ's
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