S7-400F/FH meet the following safety requirements:

• Requirement classes AK 1 to AK 6 in accordance with DIN V 19250/DIN V VDE 0801
• Safety requirement classes SIL 1 to SIL 3 in accordance with IEC 61508
• Categories 1 to 4 according to EN 954-1

Mode of operation

The safety functions of the S7-400F/FH are contained in the F program of the CPU and in the safety-related signal modules (F-modules).

The signal modules monitor output and input signals by means of discrepancy analyses and test signal injections.

The CPU checks the proper operation of the controller with regular self-tests, command tests, and logical and chronological program execution checks. In addition, the I/O is checked by means of sign-of-life requests.

If a fault is diagnosed in the system, the system is brought to a safe state.

F-Runtime license

The S7 F-Runtime license must be loaded onto the CPU S7-400H to operate the S7-400F/FH. One license is required for each S7-400F/FH.

Programming

The S7-400F/FH is programmed in the same way as the other SIMATIC S7 systems. The user program for non-safety-related plant sections is created with time-tested programming tools such as STEP 7.

S7 F Systems option package

The option package "S7 F Systems" is required for programming the safety-related program sections. The package contains all the necessary functions and blocks for creating the F program. The following software packages must be loaded onto the PG/PC for S7 F Systems to run:

• STEP 7 as of V5.4 SP3 HF7
• CFC as of V7.0 SP1 HF7
• Optional: SIMATIC PCS 7 as of V7.0 SP3

For the F program with the safety functions, special function blocks from the F library are called up with CFC and interconnected. The CFC simplifies the configuring, programming and the acceptance testing of the system. Programmers can concentrate fully on the safety-related application without having to use additional tools.