Siemens SIMATIC ET 200S Installation And Operating Manual page 85

Conditions for Achieving Safety Class
The conditions for achieving the respective safety classes are summarized in the following
table.
Table 7-8
Condition
ET 200S standard modules supplied by means of P2
The relays are switched at least once during the time of occurrence
of the second fault; power is not supplied to ET 200S standard
modules via P2
Power Module Supplies for Standard ET 200S Modules
Warning
Always connect the 24 VDC supply for the standard ET 200S modules on the
PM-E F pp DC24V PROFIsafe. Otherwise, the outputs of DO modules may exhibit safety
critical behavior.
Warning
When supplying standard DO modules, always use the terminal modules to supply actuators
(actuator feedback on the DO module). Otherwise, the power module signals a short circuit
and the load voltage of this voltage group is interrupted.
Double Chassis Cable Necessary
Warning
For the PM-E F pp DC24V PROFIsafe, the chassis cable to the terminal module must be
installed twice for safety reasons. Otherwise if there was an interruption on a single chassis
cable, a safety-related shutdown of voltage bus P2 would not be possible.
ET 200S Distributed I/O System - Fail-Safe Modules
Hardware Installation and Operating Manual, 07/2005, A5E00103686-04
PM-E F pp DC24V PROFIsafe: Conditions for AK/SIL/Category
7.3 PM-E F pp DC24V PROFIsafe power module
Achievable AK/SIL/Category
AK4/SIL2/Category 3 on P2
AK6/SIL3/Category 4 on P2
Fail-Safe Modules
7-25