Siemens SIMATIC PCS 7 Function Manual page 185

● The OS client is not switched over from the failed OS server to its redundant OS partner
● When the failed OS server is available once again to the OS client, the OS client
Disrupted network connection to the AS
If a fault occurs on the plant bus connection between the OS server and the AS, WinCC
Redundancy reacts as follows:
● The disruption of the plant bus connection is reported to the OS partner server.
● The OS partner server receives the message that the OS server has failed.
● The OS partner server saves the date and the time of day of the OS server failure.
● An OS client is automatically switched over from the failed OS server to its redundant OS
When the process connection to the OS server is restored, the missing data in the archive of
the OS server is updated by the procedure described below. Condition: The "Synchronization
after process connection error" option must be selected in the "General" tab of the
"Redundancy" dialog box for this.
● The OS partner server saves the date and the time of day marking the return of the OS
● The data gaps in the archives of the failed OS server are updated by the data from the
● When the process connection is restored, this is announced by a process control message
PC station identified as faulty
In PCS 7, the PC stations are preset in such a way that the network adapters are automatically
deactivated when a PC station is identified as faulty. Depending on the Autostart settings, a
manual reboot is required or an automatic reboot of the server is triggered.
Note
Terminate process mode on redundant systems
If the process mode of the PC station is to be terminated manually and the redundancy partner
of the PC station is not available, a corresponding message points out this situation. In this
case, you can cancel the process for terminating process mode. These actions are logged.
Fault-tolerant Process Control Systems (V8.0)
Function Manual, 03/2012, A5E02779471-02
server because the OS server is not available.
automatically switches back to its preferred server.
partner server. Condition: The "WinCC client switch in case of a process connection error"
option must be selected in the "Redundancy" dialog box for this.
server.
memory of the OS partner server. The process data of all automation systems (even those
that have not failed) are synchronized.
in the message list.
Failure, Switchover and Return of Fault-tolerant Components
6.4 OS server
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