Siemens SIMATIC Operating Instructions Manual page 32

Wiring
4.4 Requirements for Sensors and Actuators
If the actuators are operated at voltages greater than 24 V DC (for example, 230 V DC) or if
the actuators switch higher voltages, safe isolation must be ensured between the outputs of
a fail-safe output module and the components conducting the higher voltage (in accordance
with EN 50178).
This is generally the case for relays and contactors. Particular attention must be paid to this
requirement for semiconductor switching devices.
See also
Assignment of PROFIsafe Address (Page 24)
Technical Specifications for the 8/16 F-DI DC24V PROFIsafe Electronic Module (Page 84)
Technical Specifications for the 4/8 F-DI/4 F-DO DC24V/2A PROFIsafe Electronic Module
(Page 103)
Technical Specifications for the F-Switch PROFIsafe Electronic Module (Page 136)
32
WARNING
ET 200pro Distributed I/O System - Fail-Safe Modules
Operating Instructions, 05/2007, A5E00394073-02