SIMATIC S7-400FH controllers, with redundant controllers are used for extended system availability in order to satisfy safety and fault-tolerance demands. For use as a safe controller, the user can expand the standard CPU to include safety-relevant functions with the S7-F Systems software package. This makes it possible to integrate safety-relevant and fault-tolerant tasks inexpen­sively into the standard automation system.

Two controllers are available for the SIMATIC S7-400FH to suit different performance requirements, CPU 414-4H or CPU 417-4H. The most
important characteristic data are shown in the "Overview of controllers".

Benefits for the safety controllers from Siemens:
	Coexistence of standard and safe program in one CPU possible
	The SIMATIC PCS 7 process control system can very easily integrate the SIMATIC fail-safe controllers.
	Easy programming with CFC (Continuous Function Chart) and Safety Matrix (cause & effects method)
	Easier handling thanks to integrated redundancy
	Uninterruptible operation in case of CPU failure
	Redundant S7-400FH can be set up at separate locations - up to 10 km apart
	The safe, fault-tolerant SIMATIC controllers fulfill the demands of the highest safety level: - IEC 61508 (up to SIL 3) - EN 954 (up to Category 4) - TÜV certificate no: Z2 03 04 38282 002

Overview of controllers: