Siemens SIMATIC PCS 7 Function Manual page 224

Failure, Switchover and Return of Fault-tolerant Components
6.10 Guidelines for updating a redundant OS in runtime
Phase 5 / 8. Server_1: Check and save the "Redundancy" dialog box
● Open the "Redundancy" editor and check the settings in the dialog box. Click "OK" to exit
the dialog box even if you have made no changes.
Phase 5 / 9. Server_1: Check and save the "Time Synchronization" dialog box
● Open the "Time Synchronization" editor and check the settings in the dialog box. Click "OK"
to exit the dialog box even if you have made no changes.
Phase 5 / 10. Server_1: Activate WinCC Runtime
● Activate WinCC Runtime on Server_1.
Phase 5 / 11. Carry out Phase 5: Steps 1 to 10
If you are using more than one redundant OS server pair, repeat steps of Phase 5 / step 1
through 10 for each Server_1.
Phase 5 / 12. ES: Starting SIMATIC PDM
Start the SIMATIC PDM on the ES, if installed.
The system reacts as follows:
● Server_1 becomes standby server.
Result after Phase 5
● Updated Server_1 is standby server.
● Updated Server_2 is master server.
● Updated Client_1 is connected to its preferred server Server_1.
● Updated Client_2 is connected to its preferred server Server_2.
The updating of your redundant operator stations is complete.
Maintenance client accesses to intelligent field devices are possible when the PDM server has
been started on the engineering station.
NOTICE
Archive data
When using a Process Historian, only the latest archive data from the operator stations is
available.
Archive data from swapped out archives and archive data from a previously used central
archive server may need to be migrated.
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Fault-tolerant Process Control Systems (V8.1)
Function Manual, 11/2014, A5E34878832-AA