Siemens Simatic PCS 7 Function Manual page 21

Note
The numbering of the components in the illustration relates to the descriptions provided below.
Number
1
2
3
4
5
6
7
8
9
High Availability Process Control Systems (V9.0)
Function Manual, 05/2017, A5E39221836-AA
Description
Several clients (OS clients, BATCH clients, Route Control clients) can access data on a
server (OS server, BATCH server, Route Control server).
Communication between the operator stations (client and server) and communication with
the engineering station is over a redundant, high availability terminal bus (Industrial Ether‐
net).
The clients and server are connected to the terminal bus via switches.
The servers (OS server, BATCH server, Route Control server, maintenance server, central
archive server) can, when necessary, be set up redundantly.
Automation systems communicate with the OS servers/Route Control servers and engi‐
neering stations and among themselves over the redundant, high availability plant bus (In‐
dustrial Ethernet).
The automation system, server and engineering station are connected to the plant bus via
switches.
Each part of the redundant, high availability S7-400H automation systems is connected to
the plant bus with an Ethernet communications processor (CP).
Each part of the AS is connected to several fieldbus chains (their PROFIBUS DP). The
internal fieldbus interfaces or additional communications processors are used for the at‐
tachment.
The redundant connection to the fieldbus system is achieved by using two interface modules
in each distributed I/O device (e.g. ET 200M on PROFIBUS DP).
Using redundant digital or analog input/output modules, you can evaluate signals from sen‐
sors/actuators. If one of the two redundant modules fails, the input/output signal of the func‐
tioning module are evaluated.
Single Fieldbus systems can be connected to the redundant PROFIBUS DP.
The configuration of a redundant fieldbus can be realized with a redundant gateway (for
example, PA link). The field devices are connected to the subsystem (for example, PROFI‐
BUS PA) via AFD, active field distributors, (or AFS when ring/coupler redundancy is used).
The Y Link allows you to connect non-redundant PROFIBUS distributed I/O devices to a
redundant PROFIBUS DP.
Basics of high availability
3.3 PCS 7 redundancy concept
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