Design and functions
Normally, two WinCC stations or process data servers run completely in parallel, which means each station has its own process connection and own archives. The clients that are connected to the servers can be distributed to the servers as required, which leads to a reduced load. When one of the two WinCC stations fails, the other takes over the archiving of messages, process data and user data. This ensures complete data integrity. In client/server mode, the clients are automatically switched from the failed server to the redundant partner. This ensures continuous plant visualization and operation on every operator station.
When a failed partner is restored, all of the archived process values, messages (including statuses, acknowledgements, lists and comments), data from the user archive of the failure period and internal tags are automatically synchronized with the partner in the background – without affecting the running system. Once this is complete, two equivalent servers/stations will be available again. The clients connected to the servers are distributed among their original server partners again. The automatic switchover to the redundant partner takes place not only when a server fails, but also in case of disturbed S7 process communication or faulty applications.
Additional increase in system availability
In addition to the option of using two servers connected in parallel via the WinCC/Redundancy option, you can also design the communication channels to the controller redundantly in a WinCC application. Two communications processors are plugged in and the communication paths are doubled. The use of fail-safe SIMATIC S7 controllers can, if required, further increase availability at the control level. Combining the system solutions creates a security concept that meets even high demands.