Windows domains and users

A Windows domain is a network of computers with a common security database. If the PI Interface for OPC DA node and the OPC server are members of the same domain (including domains with bi-directional trusts), domain users can be used in DCOM access control lists. If the interface and server reside in different domains, you must configure identical local accounts on both machines and use those accounts in ACLs. These accounts must have the same user name and password, and password expiration for these accounts must be disabled.

If the interface and the OPC server are on the same computer, any account that is recognized by that computer can be used, including the SYSTEM built-in account. Some OPC servers implement custom security. In this case, the account must be granted access to the OPC server, apart from any DCOM permissions.

Computers in Windows workgroup configuration have default policies that interfere with OPC server/client communications, requiring you to disable simple file sharing.