Failsafe systems provide the highest level of safety for humans, machines and the environment. They are used to avoid accidents and damage caused by faults and malfunctions. The failsafe controllers (SIMATIC Safety Integrated) monitor themselves, detect faults autonomously and immediately change into or remain in a safe state when a fault occurs.

Redundant systems ensure the highest level of availability for plant and process. These systems have redundant configurations. When a fault occurs which was caused by a hardware problem, these systems switch automatically without any loss of data.

The failsafe, fault-tolerant controllers of SIMATIC S7-400FH combines both functions in one system.