The safety SIMATIC controllers are based on a standard CPU whose operating system and hardware components were expanded to include a variety of different protective mechanisms. They can be used as standard CPUs.

Safety-related tasks can thus be economically implemented using only one CPU or as always in separate design.

The safety CPUs can be expanded with ET 200M, ET 200S, ET 200pro (IP67) signal moduls and/or digital block peripheral device ET 200eco (IP67).

PROFIBUS or PROFINET with PROFIsafe profile is used for communication between two safety CPUs or between a safety CPU and the safety I/O allocated to it.