Configure DCOM settings for the OPC client node

On client computers that access OPC servers, you must enable DCOM and grant appropriate account access.

Note: The procedure below provides general instructions for configuring DCOM settings for the OPC client node. It is likely that your company's IT specialist will need to consult with your OPC server vendor to identify the DCOM settings required for your security arrangement. Error codes generated by the OPC foundation will help to determine your correct DCOM configuration.

To configure the required settings, perform the following steps:

1. In a command window, issue the dcomcnfg command. The Component Services window is displayed.

2. Expand Console Root > Component Services > Computers, right-click My Computer and then click Properties.

3. In the My Computer Properties window, click the Default Properties tab and set the appropriate settings:

   1. Select the Enable Distributed COM on this computer check box if the OPC client must connect to an OPC server running on a different computer. DCOM can be disabled if the client and server run on the same computer. Disabling DCOM is secure but doing so disables many remote management functions.

   2. Set Default Authentication Level to Packet Integrity.

   3. Set Default Impersonation Level to Identify.

   4. If the OPC user account is a local user account, click the COM Security tab, and add the account to the appropriate access control lists (ACLs) as follows: Under Access Permissions, add the user (and the OPC administrator) to both the Limits and Defaults ACLs. Set Access Permissions for the default users and groups as follows:

      Permissions	User	Setting	Access Type(s)
      Limits	Everyone	Allow	Local Access and Remote Access
      	ANONYMOUS LOGIN	Allow	Local Access
      Default	SELF	Allow	Local Access and Remote Access
      	SYSTEM	Allow	Local Access

4. Under Launch and Activation Permissions, add the user to both the Limits and Defaults ACLs. Set the Launch and Activation Permissions for the default users and groups as follows:

   Permissions	User	Setting	Access Type(s)
   Limits	User under which OPC Server runs, or Administrators	Allow	Local Launch Remote Launch Local Activation Remote Activation
   	Everyone	Allow	Local Launch and Local Activation
   Default	User under which OPC Server runs, or Administrators	Allow	Local Access and Remote Access (or Launch and Activation, depending on your Windows operating system)
   	INTERACTIVE	Allow	Local Access and Remote Access (or Launch and Activation, depending on your Windows operating system)
   	SYSTEM	Allow	Local Access and Remote Access (or Launch and Activation, depending on your Windows operating system)