Tailored redundancy
... with redundant I/O

SIMATIC S7-400H sets completely new standards in terms of flexibility, modularity and redundancy and supports fault-tolerant architectures. The level of fault tolerance can be perfectly tailored to different requirements by mixing and coordinating single and multiple redundancies in one and the same system.

Redundant I/O devices for maximum availability
The system tolerates the failure of a signal module as well as the failure of a CPU, a PROFIBUS line, or the interruption of a PROFINET ring.

Your benefits

Thanks to this flexibility, redundancy only has to be providedwhere it is actually needed. This permits less complexand more cost-effective solutions than conventionalarchitectures with a standardized design.

Principle of redundant periphery

Redundant I/Os are input and output modules that are redundantlyconfigured and operated.
During fault-free operation, both modules are active: For example, in the case of redundant inputs, the values of the shared sensor are read in by two modules, and the result is compared and made available to the user as a unified value for further processing.

In the case of redundant outputs, the value calculated by the user program is output by both modules. In the event of afault, e.g. if one of the two output modules fails, the defective module is no longer addressed, the fault is signaled and processing continues with the intact module only. Followingr epair, which may be carried out during operation, both modules can be addressed again.

Flexible Modular Redundancy (FMR) with PROFIBUS I/O

The availability is scalable in accordance with the redundant I/O configuration:

1. Each module in a separate rack with redundant connectionto PROFIBUS


2. Each module in a separate rack with single connection toPROFIBUS


3. Both modules in one rack