Siemens SIMATIC S7-400H - Communications Via a Point-To-Point CP on the ET 200 M; Connection Via ET 200 M

Communication Functions
8-19
Automation System S7-400H Fault-tolerant Systems
A5E00068197-07
8.5.3 Communications via a Point-to-Point CP on the ET 200M
Connection via ET 200M
Connections of fault-tolerant systems to single-channel systems are frequently
possible only through a point-to-point connection since many systems have no
other connection option.
To have the data of a single-channel system available on the CPUs of the
fault-tolerant system as well, the point-to-point CP (CP 341) has to be inserted in
a distributed mounting rack with two IM 153-2s.
Configuring connections
Redundant connections between the point-to-point CP and the fault-tolerant
system are not necessary.
CPUa2
CPUa1
IMa1
IMa2
Cable
CPU
a1
CP
443-5
Ext
Fault-tolerant system a
2 x IM153-2 CP
PtP
ET 200M
Redundancy
block diagram
Fault-tolerant system a
CPU
Single-channel other system
CP
CP PtP CPUCP PtP
Single-channel other system
Figure 8-12 Example of interconnection of a fault-tolerant system and a single-channel
third-party system
Response to failure
Double faults in the fault-tolerant system (in other words, CPUa1 and IM153-2) and
a single fault in the third-party system result in a complete failure of communication
between the systems involved (refer to Figure 8-12).
The point-to-point CP can alternatively be inserted centrally in “fault-tolerant
system a”. But with this configuration even a failure of the CPU results in a
complete failure of communication.