Basics And Terminology Of Fault-Tolerant Communication - Siemens SIMATIC PCS 7 System Manual

Options for terminating the communication connection
The following events are available for terminating communication connections:
● You program the termination of the communication connection with FB 66 "TDISCON".
● The CPU state changes from RUN to STOP.
● At POWER OFF / POWER ON
Connection diagnostics
In Step 7, you can read detailed information on the configured connections by selecting
"Module state -> Communication -> Open communication over Industrial Ethernet".
Reference
For detailed information on the blocks described above, refer to the
16.7

Basics and terminology of fault-tolerant communication

Overview
When more stringent requirements for overall plant availability exist, it is necessary to
increase the reliability of the communication, i.e., by configuring the communication
redundantly as well.
Below you will find an overview of the fundamentals and basic concepts which you ought to
know with regard to using fault-tolerant communications.
Redundant communication system
The availability of the communication system can be increased by duplicating
subcomponents, duplicating all bus components, or using a fiber-optic ring.
On failure of a component, the various monitoring and synchronization mechanisms ensure
that the communication functions are taken over by the standby components during
operation.
A redundant communication system is essential if you want to use fault-tolerant S7
connections.
Fault-tolerant communication
Fault-tolerant communication is the deployment of S7 communication SFBs over fault-
tolerant S7 connections.
Fault-tolerant S7 connections need a redundant communication system.
CPU 410-5H Process Automation/CPU 410 SMART
System Manual, 09/2014, A5E32631667-AB
16.7 Basics and terminology of fault-tolerant communication
Supplementary information
STEP 7 Online Help.
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