The Cpus S7-400H For Fault-Tolerant Controllers - Siemens SIMATIC S7-400 Configuration And Use Manual

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The CPUs S7-400H for Fault-tolerant Controllers

Introduction
You use redundant automation systems to increase availability and avoid
production losses.
The higher the costs of a production standstill, the more worthwhile it is to use a
fault-tolerant system. The investment costs associated with a fault-tolerant system
is quickly offset by the savings resulting from decreased production downtime.
The S7-400H automation system meets the high requirements for availability,
intelligence and distributed operation that are required of modern automation
systems. It also features all the functions for acquiring and preparing process data
and for controlling, regulating and monitoring equipment and plants.
Tiered Availability with Redundant Components
The S7-400H is designed with redundancy so that it remains available in every
situation.
This includes the CPU, the power supply and the hardware for interconnecting the
two CPUs.
The two CPUs form the core of the S7-400H. You set the rack numbers of the
CPUs with a switch at the back. The two subsystems can be identified by their
respective rack number.
You yourself can decide which components to implement redundantly to increase
their availability based on the process you are automating.
Synchronization Modules
Synchronization modules are used for the communication between two redundant
S7-400H CPUs. They are integrated into the CPUs and interconnected via fiber
optic cables. You need two synchronization modules for each CPU.
There are two types of synchronization modules, one with a cable length of 10 m
between the CPUs and another with a cable length of up to 10 km.
You can replace a synchronization module when it is energized. This supports the
repair scenario for H systems and thus can overcome the failure of the redundant
connection without having to bring the plant to a stop.
Automation System S7-400 Configuration and Use
A5E00442711-02
CPUs of the S7-400
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