Siemens SIMATIC S7-400H - Page 174

Communication Functions
8-4
Automation System S7-400H Fault-tolerant Systems
A5E00068197-07
CPU b2
CPU b1
CPU a2
CPU a1
CP a1
CP a2
CP b1
CP b2
Bus 1
Bus 2
Fault-tolerant
system a
Fault-tolerant
system b
Bus 1
Bus 2
CPU
a1
CP
a1
CPU
b1
CP
b1
Redundant connections
CPU b2
CPU b1
CPU a2
CPU a1
CP a1
CP a2
CP b1
CP b2
LAN (red.)
Redundant connections:
CPU a1 –> CPU b1, CPU a2 –> CPU b2, CPU a1 –> CPU b2, CPU a2 –> CPU b1
CPU
a1
CP
a1
CPU
b1
CP
b1
OLM
OLM
OLM
OLM
System bus as optical two-fiber ring
Fault-tolerant system a Fault-tolerant system b
Figure 8-2 Example of the number of resulting partial connections being dependent on
the configuration
Should the active partial connection fail, a previously established second partial
connection assumes responsibility for communications.