Siemens S7-300 Installation And Operating Manual page 22

Configuration options
2.3 Configuration with F-SMs in Safety Mode
Rules for using the safety protector
The safety protector is used to protect the F-SMs from any overvoltage developing in the
case of a fault/error.
The safety protector must be used for SIL3/Category 4/PLe applications:
 Only with operation of
 if the F-SMs are integrated centrally in an S7-300.
 if the PROFIBUS DP is wired using a copper cable.
 If PROFIBUS DP is installed with fiber-optic cables, and if standard and fail-safe signal
Configuration variants depending on availability
Table 2- 1
In system
Distributed
S7 F/FH
Systems
22
WARNING
– SM 336; AI 6 x 13 Bit (6ES7336-1HE00-0AB0)
– SM 326; DI 8 x NAMUR (6ES7326-1RF00-0AB0)
– SM 326; DO 10 x DC 24V/2A (6ES7326-2BF01-0AB0)
– SM 326; DI 24 x DC 24V (bis 6ES7326-1BK01-0AB0)
– SM 326; DO 8 x DC 24V/2A PM (6ES7326-2BF40-0AB0)
modules must be operated on the same ET 200M.
Configuration variants of fail-safe systems based on availability
Configuration variant
Single-channel I/O
S7

Safety
Single-channel
S7 FH

switched I/O
systems
Redundant switched

I/O
Description
Single-channel, fail-safe (F-CPU and F-
SMs not redundant)
Single-channel, switched, fail-safe
(redundant F-CPU, F-SMs not
redundant; system changes to the other
F-CPU in case of error)
Multi-channel, fail-safe (redundant F-
CPU, PROFIBUS DP and F-SMs)
Installation and Operating Manual, 01/2010, A5E00085586-10
Availability
Normal
availability
Enhanced
availability
Highest
availability
Fail-safe signal modules