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Software Toolbox DCOM Tutorial

DCOM for Windows 7, 8, & Server 2008

There are five steps to configuring DCOM.

To start the DCOM Configuration type “DCOMCNFG.EXE” from the start menu

Note: In Windows 8 you may just begin typing at this page, as it is the new start menu:




The DCOM Config tool may take a few seconds to open. You will see the window below once the DOCM Config tool opens up.


Configuring General/Default Settings
Click on the Computers and then right click on “My Computer” and choose “Properties”.

Component Services

Then choose Default Properties on the far Right.

Default Properties Tab - Settings

Configure the following options as follows:

  • The Enable Distributed COM on this computer MUST be checked.
  • The Default Authentication Level should be set to None.
  • The Default Impersonation Level should be set to Identity.

    Now click on the “COM Security” tab.
COM Security Settings

Each highlighted button will need to be changed.

Click on the “Edit Default” button within the “Access Permissions” area and make sure the following accounts exist with the “Allow Access” permissions.

  • Anonymous
  • Everyone
  • Guests
  • Interactive
  • Network
  • System
Edit Default Example

If you plan to use IIS (Internet Information Services) as an OPC Client, then its login context should be added to the list of trusted accounts as shown above.

  • IWAM_<computer-name>
  • IUSR_<computer-name>

Do the same with the Edit Default button in the Launch Permissions section and give the right Allow Launch to the same accounts as above.

Make sure the same settings are used under both Edit Limits buttons. This is going to create minimal security for your DCOM settings. This is just to ensure we can establish a working connection. After all the settings have been configured and the connection is established security can be tightened.

Now click OK to save and close the window..

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