Supplementary information
18.10 Communication via S7 connections
CPU 410 Process Automation/CPU 410 SMART
326
System Manual, 05/2017, A5E31622160-AC
Note
The START and STOP communication functions act on exactly one CPU or on all CPUs of
the fault-tolerant system. More detailed information is available in Reference Manual
System
Software for S7-300/400 System and Standard Functions
.
Note
Downloading the connection configuration during operation
If you download a connection configuration during operation, established connections may
be terminated.
18.10.1
Communication via S7 connections - one-sided mode
Availability
Availability for communication between a fault-tolerant system and a standard system is also
increased by using a redundant plant bus instead of a single bus (see figure below).
Figure 18-8 Example of linking standard and fault-tolerant systems in a simple bus system
With this configuration and redundant operation, the fault-tolerant system is connected to the
standard system via bus1. This applies no matter which CPU is the master CPU.
For linked fault-tolerant and standard systems, the availability of communication cannot be
improved by means of a dual electrical bus system. To be able to use the second bus
system as redundancy, a second S7 connection must be used and managed accordingly in
the user program (see next figure).