Siemens SIMATIC PCS 7 Operation And Maintenance page 19

SSM (Split Screen Manager)
You must specify a standard server for the SSM component if you want to compile trend
groups or screen compositions on an OS client and store them on the standard server.
If no standard server is configured for the SSM component on the OS client, the compiled
trends are saved locally on this computer. Other OS clients cannot have these trend groups
displayed in the Online Trend Control. The same applies to screen compositions.
When redundancy is configured on an OS server, the data of the trend groups and the
screen compositions are also synchronized on the respective redundant partner server. This
means all compiled trend groups and screen compositions can be called up from all OS
clients when you perform a redundancy switchover.
The configured standard servers will be displayed in the "Server Data" menu in the WinCC
Explorer of the OS client, as shown in the following example.
Example
Loaded server data (package) without standard server
Loaded server data (package) with standard server
Scenario
A PCS 7 plant contains three non-redundant OS servers. The server data from three OS
servers is assigned to an OS client. If a non-redundant OS server has been configured on
the OS client as the standard server for alarms and SSM and this OS server needs to be
deactivated, then:
● The OS areas of an OS server not in process mode cannot be operator-controlled.
● No operator messages will be generated for the OS areas that can still be operator-
controlled while the server is shut down.
● The configured compilations of trends are not available. The same applies to OS servers
still in process mode.
● The configured screen compositions are not available. The same applies to OS servers
still in process mode.
Compendium Part D - Operation and Maintenance (V9.0)
Operating Manual, 02/2018, A5E43228948-AA
Installing updates and service packs
3.3 Checking plant status
19