Siemens SIMATIC PCS 7 Function Manual

4.5 Solutions for OS servers
Redundant OS servers
PCS 7 enables you to configure two OS servers redundantly for high availability operation.
This ensures that you can monitor and control your process at all times. The solution represents
the entry level into high availability process control systems.
Configuration
The figure below shows an example of a configuration with redundant OS server and Process
Historian.
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Functionality
Redundant OS servers monitor each other in runtime. If one OS partner server fails, the event
is detected in time.
If one of the two OS server fails, the OS partner server takes over the process. The interface
between OS clients and the automation system remains available.
The OS clients are automatically switched to the redundant OS partner server. This means
that the OS clients always remain available for the control and monitoring of the process. During
the failure period, the redundant OS partner server continues to archive all messages and
process data in the WinCC project. Once the failed OS server comes back online, the contents
of all the message, process value and user archives are automatically copied to the returning
OS server. This copy process is referred to as redundancy synchronization. Redundancy
synchronization fills the gaps in the various archives that result from failures.
During the failure period, the internal master/standby identification changes from the failed OS
server to its OS partner server. The master identification remains with the OS partner server
even when the failed OS server comes back online.
Configuring the archives
Tag logging and alarm logging have to be configured functionally identical for redundant OS
servers. Functionally identical configuration means the same archives, whereby extensions in
the form of additional measuring points and archives are permitted.
High availability solutions in PCS 7
4.5 Solutions for OS servers
High Availability Process Control Systems (V9.0)
94 Function Manual, 05/2017, A5E39221836-AA

Siemens SIMATIC PCS 7 Specifications

General

Brand	Siemens
Model	SIMATIC PCS 7
Category	Control Systems
Language	English