DCOM setup

 

Starting DCOM Configuration

The DCOM Configuration utility does not have an  associated icon in neither the Windows Control Panel, nor the Windows START  button.. Therefore, you have to start it manually:

Click on the Windows START button

Click on the RUN option

Type "DCOMCNFG" (without the quotes) and press ENTER. (case does not matter)

This will load the Windows "Component Services", which is shown below:

Figure 1. Default tab

 

 

 

Step 1 - Configuring Default Properties for Windows XP & 2003 Operating Systems

 

The following screen is opened by:

Right clicking on the "My Computer" node in the "Component Services" screen.

Choosing "Properties" from the menu.

This particular screen is not 100% identical to that of Windows NT, 2000 as there are more options in some areas, and fewer options in others...

Once in this Properties screen, do click on the "Default Properties" tab  first.

The options available in this screen should be configured as:

The Enable Distributed COM on this computer MUST be  checked.

The Default Authentication Level should be set to Connect.

The Default Impersonation Level should be set to Identity

The next step is to click on the "Default COM Security" tab, which is shown below:

Figure 2. Default COM security

 

There are only 2 buttons in this screen, whereas there are  3 in Windows NT and 2000 Operating Systems.

Click on the "Edit Default" button within the "Access Permissions" area and make sure that the following accounts exist with the  "Allow Access" permissions:

Everyone

Interactive

System

Network

 

Once that is complete, do the same with the "Edit Default" button in the "Launch Permissions" section and give the right "Allow Launch" to the same accounts as mentioned in the bullet-points above.

 

Now click the OK button to save and close the window.

 

 

Step 2 - Configuring DCOM Security Options for OPCENUM for Windows XP & 2003 Operating Systems

 

The next step is to locate OPCEnum in the list of COM components. Simply click on, or expand the "DCOM Config" section to show the objects available to configure:

 

Figure 3. DCOM services

Locate OPCEnum, and then open its properties by simply right clicking on it, and choosing "Properties" from the menu.

 

Figure 4. General Tab

General Tab

 

The  General Tab has only one option, and that is the "Authentication level".

For each of use, you can select "None" as your option.

 

Figure 5. Location Tab

Location Tab

 

OPCEnum  is a program that scans your registry for a list of OPC Servers on your  computer.

OPCEnum needs to run on the computer where it resides.. therefore the option of choice here is to check "Run application on this computer ".

 

Figure 6. Security Tab

 

Security Tab

 

Three options in the Security tab that need to be set.

Launch Permissions:                        Select the option "Use Default".

Access Permissions:                          Select the option "Use Default".

Configuration Permissions:            Select the option "Customize", and then

click the "Edit" button.

 

A window will open allowing to specify the accounts that do/don't have  configuration permissions, simply add the same "Network, Interactive, System and Everyone" groups as we have previously, and make sure that they have "Full Control" rights.

 

 

 

 

 

End Points Tab

Use either the Interactive or System account.

Click OK to save and close the OPCENUM options window.

 

Last Step  - Configuring DCOM Security Options for the OPC Server, for XP & 2003 Operating Systems

This step should only be followed if your computer has an OPC Server on it that you wish to allow OPC Clients to connect to.

At the "Component Services" window, click on or expand the "DCOM Config" node  and locate your OPC Server from the list.

 

Figure 7

When you have found your OPC Server in this list, simply right-click on it and open it's properties. Then follow the same steps as those listed for configuring OPCENUM.