DCOM Tutorial - Intro to the DCOMCNFG.EXE Utility
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What is DCOM Config (aka "DCOMCnfg")?
DCOM settings are stored in the Registry. "DCOMCNFG" is a native Windows utility that is hidden and
accessible when running the command "dcomcnfg" (from Start > Run).
So where is the DCOM Config Utility on my computer?
Dcomcnfg is like many Microsoft tools... it exists, but only to those who know about it because it is
hidden. It should be installed in your \Winnt\System32 directory on either NT or 2000 and the file is named DCOMCNFG.EXE.
What does the DCOM Config Utility Look like?
Depending on your operating system will determine what the utility looks like. Pre Windows XP computers
look like below...
... whereas Windows XP and newer look like...
How should I use DCOM Config ?
There are 3 major things that you may need to set with DCOM Config
- OPC client PC settings (more info) to allow
OPC Servers to communicate with OPC Clients.
- OPC server PC settings (more info) to allow OPC Clients to communicaet to OPC Server.
- On your OPC server machine (more info), setup OPCEnum to allow OPC Clients to query
what OPC Servers are available.
Things to remember when using DCOM Config
- When changing DCOM permissions, you need to restart OPC applications.
- Sometimes Windows will CACHE DCOM settings; sometimes a Reboot is necessary.
- Once you get your DCOM Config settings right, you should not have to change them again.
- Document your settings carefully - make screenshots if you want and paste them into a Word
document. Proper and organized documentation of how you have your machine setup can be
a lifesaver if you have to reload a machine in an emergency (i.e. drive failure, hardware failure, etc).
DCOM Config Screenshots - provided as a reference for the above descriptions.
Default Properties Tab
Default Security Tab
Default Protocols Tab
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