Supplementary information   
18.11 Communication via fault-tolerant S7 connections 
  CPU 410 Process Automation/CPU 410 SMART 
332  System Manual, 05/2017, A5E31622160-AC 
 
Communication via fault-tolerant S7 connections 
Availability of communicating systems 
Fault-tolerant communication expands the overall SIMATIC system by additional, redundant 
communication components such as CPs and bus cables. To illustrate the actual availability 
of communicating systems when using an optical or electrical network, a description is given 
below of the possibilities for communication redundancy. 
The essential requirement for the configuration of fault-tolerant connections with STEP 7 is a 
configured hardware installation. 
The hardware configuration in both subsystems of a fault-tolerant system 
 be identical. 
This applies in particular to the slots. 
Depending on the network used, CPs can be used for fault-tolerant and fail-safe 
communication, see Appendix Function and communication modules that can be used in a 
redundant configuration (Page 389)  
Industrial Ethernet with ISO protocol or PROFIBUS without distributed I/O and ISO on TCP 
is supported. Fault-tolerant S7 connections via Industrial Ethernet with ISO on TCP are 
supported by the integrated PN interfaces and corresponding CPs. You require a suitable 
CP for fault-tolerant S7 connections via Industrial Ethernet with ISO protocol or via 
PROFIBUS. These connections are not possible via the internal PROFIBUS-DP interface.  
Only Industrial Ethernet is supported for connecting to PC stations using fault-tolerant S7 
connections. To be able to use fault-tolerant S7 connections between a fault-tolerant system 
and a PC, you must install the "S7-REDCONNECT" software package on the PC. The 
software is part of the SIMATIC Net CD. As of version 8.1.1, communication over ISO-on-
TCP is also supported. Please refer to the product information on the SIMATIC NET PC 
software to learn more about the CPs you can use at the PC end.  
Communication combinations 
The following table shows the possible combinations of fault-tolerant connections via 
Industrial Ethernet. 
 
Local connec-
tion  
end point 
Local network con-
nection 
Remote  
network connection 
Remote connec-
tion  
end point 
CPU 410  CPU-PN interface 
CP443-1 (EX 20/30) 
CP443-1 (EX20/30) 
TCP 
TCP 
TCP 
CPU-PN interface 
CPU-PN interface 
CP443-1 ( EX 30 ) 
TCP 
TCP 
TCP 
CPU 410 
CPU 41xH 
V6/CPU 410 
CPU 41xH V4.5 
and higher/CPU 
S7 fault 
tolerant 
connection 
via 
ISOonTCP 
CPU 410  CP443-1 (EX 20/30)  ISO  CP443-1   ISO  CPU 41xH /CPU 
410 
S7 fault 
tolerant 
connection