How to configure DCOM in order for Reliance to be able to connect to a communication driver on a remote computer

August 1, 2010

Reliance's communication drivers are DCOM servers (also called DCOM objects). Thus, the runtime software can connect to a communication driver located on a remote computer if DCOM is configured appropriately. The DCOM settings can be configured using the "dcomcnfg.exe" program (located in the Windows\System32 directory). The program's user interface is different in various Windows versions. However, the principles are the same.

The following steps describe configuring DCOM in Windows XP (SP1):

1. The same user account must exist on both computers, a client computer (the computer from which the DCOM server will be initialized by the runtime software) and a remote computer (the computer where the DCOM server is installed and where it will run). The user account should have administrator privileges.
2. Run the "dcomcnfg.exe" program on the remote computer.
3. In the tree diagram on the left, select "My Computer", and bring up its properties dialog ("My Computer Properties") from the pop-up menu.
4. Select the "Default Properties" tab and follow these sub-steps:
   Activate the "Enable Distributed COM on this computer" option.
   Set "Default Authentication Level" to "None".
   Set "Default Impersonation Level" to "Impersonate".


Note:

This way, you set the authentication and impersonation level for all DCOM servers. To configure only a selected DCOM server, see step 5.

5. In the tree diagram on the left, expand the "DCOM Config" folder under "My Computer", select a DCOM server, and bring up its properties dialog from the pop-up menu.
   Follow these sub-steps:
   On the "General" tab, set "Authentication Level" to "None".
   On the "Location" tab, activate the "Run application on this computer" option.
   On the "Security" tab, set "Launch and Activation Permissions" and "Access Permissions" to "Customize". Edit the list of user accounts so that it includes the account under which the runtime software on the client computer will run.
   On the "Identity" tab, select the user account to run the DCOM server on. Select "The interactive user" if you want the DCOM server to appear on the Windows desktop of the currently logged-on user. Select "The launching user" if you want the DCOM server to run on the account of the launching user. Please be aware that the DCOM server will not appear on the Windows desktop if another user is logged on at the moment. The same holds true if you choose "This user".

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