Supplementary information
16.8 Usable networks
CPU 410-5H Process Automation/CPU 410 SMART
System Manual, 10/2013, A5E32631667-AA
239
Resource requirements of fault-tolerant S7 connections
The fault-tolerant CPU supports operation of 62 fault-tolerant S7 connections (see technical
specifications). Each connection needs a connection resource on the CPU; subconnections
do not need any additional connection resources. On the CP, on the other hand, each
subconnection needs a connection resource.
Note
If you have configured several fault
-tolerant S7 connections for a fault-tolerant station,
establishing them may take a considerable time
. If the configured maximum communication
delay was set too short, link
-up and updating is canceled and the redundant system state is
no longer achieved (see Chapter
Time monitoring (Page 110)).
Your choice of the physical transmission medium depends on the required expansion,
targeted fault tolerance, and transfer rate. The following bus systems are used for
communication with fault-tolerant systems:
● Industrial Ethernet
● PROFIBUS
Additional information on the networks that can be used is available in the relevant SIMATIC
NET documentation on PROFIBUS and Ethernet.
Communication via S7 connections
Communication with standard systems
There is no fault-tolerant communication between a fault-tolerant system and a standard
CPU. The following examples illustrate the actual availability of the communicating systems.
S7 connections are configured in STEP 7.
If S7 communication is used on a fault-tolerant system, all communication functions can be
used for this.
The communication SFBs are used in STEP 7 to program communication.
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