Siemens SIMATIC S7-400H - Communications between Fault-Tolerant Systems and Pcs

Communication Functions
8-14
Automation System S7-400H Fault-tolerant Systems
A5E00068197-07
8.4.3 Communications between Fault-Tolerant Systems and PCs
Availability
When fault-tolerant systems are connected to a PC, the availability of the overall
system concentrates not only on the PCs (OS) and their data management but
also on data acquisition on the programmable logic controllers.
PCs are not fault-tolerant on account of their hardware and software
characteristics. They can be arranged in a redundant manner in a system,
however. The availability of this kind of PC (OS) system and its data management
is ensured by means of suitable software such as WinCC Redundancy.
Communications take place via fault-tolerant connections.
The “S7-REDCONNECT” software package as of V1.3 is a requirement for
fault-tolerant communication on a PC. It makes it possible to connect a PC to an
optical network with a CP or to a redundant bus system with two CPs.
Configuring connections
No additional configuration of fault-tolerant communications is required at the PC
end. Connection configuration is taken care of by the STEP 7 project in the form of
an XDB file at the PC end.
You can find out how to use STEP 7 fault-tolerant S7 communications to integrate
a PC in your OS system in the WinCC documentation.
OLM
System bus as opti-
cal two-fiber ring
OLM OLM
PC
Bus 1
2oo2 redundancy
Bus 2
CPU
a1
CP
a1
Fault-tolerant system a
WinCC
server
CP
1
PC
Redundancy
block diagram
CPUa2
CPUa1
CPa1
CPa2
Fault-tolerant
system a
CP 1
Figure 8-7 Example of redundancy with fault-tolerant system and redundant bus system