DCOM configuration example

The example describes DCOM configuration for two computers where an OPC client installed on one of them has access to the OPC server on the other one.

Figure 1:

In the case concerned, the OPC server is OPC ELUTIONS.OPCDA that gives access to data from the SCADA (ControlMaestro prev. Wizcon) system and is installed on a computer with Windows 2000 operating system, and the OPC client is DataPorter software installed on a computer with Windows 2003 Server system. Main task of this application is to share data from SCADA to GIS system.

Following description concern only DCOM configuration for OPC client and server connection (blue link on above figure) operating on two different PC machines. To configure DCOM:

1. Create an identical user account on both computers – the account with opc login and 123@opc password has been created.

2. Select Start->Run on both computers and write ”dcomcnfg” to open the DCOM configuration window (the figures below show dcomcnfg view in Windows 2003 server system).

   

   Figure 2:

3. Expand ”Component Services” on the computer, click the right mouse button and select the option ”Properties” in order to set DCOM default configuration.

   

   Figure 3:

   The window with default properties will open.

   

   Figure 4:

4. In the default properties tab, set: ”Enable distributed COM on this computer", default authentication level "Connect", default personification level "Identify".

5. In the default securities tab:

   • Access Permission – add an OPC user and set "Allow access" (the figures below show dcomcnfg view in Windows 2000 or Windows NT system)

     

     Figure 5:

   • Launch Permission - add an OPC user and set "Allow launch"

     

     Figure 6:

   • Configuration Privileges - add an OPC user and set "Read"

     

     Figure 7:

6. In the default protocols tab: standard (a default range of ports).

7. Configuration of OPCENUM (OPC Server List)

   • authentication level "Default”

   • location ”Run application on this computer”

   • securities: access "Customize" [for an OPC user (full control")], launch "Use Default", configuration "Use Default"

   • Identity: System account – the setting should not be changed for OPC Enum software

   

   Figure 8:

8. DCOM configuration for OPC ControlMaestro server:

   • authentication level "Default"

   • location ” Run application on this computer”

   • securities: access "Use Default", launch "Use Default", configuration "Customize" [for an OPC user (full control)]

   • identity: launching user

   

   Figure 9: