Why are the DCOM settings of the WinCC OPC server reset after activating the OS Runtime?
On the SIMATIC PCS 7 OS server the security settings required for operating the PCS 7 system and the OPC communication (OPC server and OPC client) are defined automatically by the SIMATIC Security Control application (SSC) or by the SIMATIC Security Controller application (SC) for PCS 7 V8.0 and higher. These include the configuration of the local Windows firewall, diverse Registry entries and other DCOM permissions.
The DCOM permissions of the components required for the OPC communication are assigned to the local user group "SIMATIC HMI".
WinCC operating mode
Depending on the operating mode of the PCS 7 OS server (WinCC - Standard mode (compatibility mode) or WinCC - Service mode), some DCOM components, in particular the OPC server, are operated with different identities.
In the Standard mode the "interactive user" (logged-in Windows user) is used.
In the Service mode the user stored in the WinCC Service mode is used.
Both the logged-in user and the Service mode user must be members of the user group "SIMATIC HMI".
Each time the PCS 7 OS server starts the user identity of the OPC server is changed according to the WinCC operating mode. In order to ensure a uniform chain of rights, you should not intervene manually in this process nor make any changes to the rights assignment, because other WinCC components are affected by this.
In particular, in the case of increased security requirements you should not use the right of "Refusal", but the required limitation of use should be made by withdrawing the relevant right.
Further information is available in the manuals listed below under "Notes on OPC".
Procedure and settings in the case of different login data of OPC client and OPC server
If the OPC client uses login data (user name, password) for accessing the WinCC OPC server that is different to that used by the OS Runtime, you must proceed as follows according to the PCS 7 version.
PCS 7 V8.1 & V8.2
According to the manual WinCC V7.4 SP1 - General information and Installation.
According to the manual WinCC V7.4 - General Information and Installation.
According to the manual WinCC V7.3 - General Information and Installation.
The relevant information is in the manual under "ServiceMode" and in the section entitled WinCC Installation Notes > Installation Requirements > Access Rights in the Operating System (reference to the SIMATIC HMI group)
PCS 7 V8.0 SP1
According to the manualWinCC V7.2: Installation / Release Notes.
The relevant information is in the sections below:
- 1.2.2Define Access Rights in Operating System(reference to the SIMATIC HMI group)
- 22.214.171.124Add Users to the "SIMATIC HMI" User Group
- 126.96.36.199Add Domain Global User Group to the "SIMATIC HMI" user group
- In the manual under the keyword "WinCC Service Mode"