Siemens SIMATIC PCS 7 Programming And Operating Manual page 29

Permanent operability for clients
SFC Visualization supports "permanent operability" for clients. A preferred server configured
on the client is used as the server. This applies regardless of whether the server is the current
MASTER or STANDBY. If there is a redundancy failover SFC Visualization reacts in
accordance with the behavior defined in WinCC.
SFC Visualization (V9.0)
Programming and Operating Manual, 05/2017, A5E41356392-AA
5.12 What you should know about OS Server and OS Client
Configuration
29