Siemens SIMATIC Operating Instructions Manual page 130

Fail-Safe Electronic Modules
8.3 F -Switch PROFIsafe Digital Electronic Module
Wiring Diagram of Standard Digital Outputs (SIL2/Category 3)
Figure 8-34
In the event of a cross circuit between 2L+ and DO or an external P-short circuit, the
controlled actuator or the 2L+ power bus is no longer switched off. You should always wire
the actuators in a cross-circuit-proof and an external P-short-circuit-proof manner, for
example, using sheathed cables or separate cable ducts, in order to prevent a cross-circuit
or an external P-short circuit.
When supplying power to standard digital output modules, always use the CM modules of
these digital output modules to supply the actuators (actuator feedback on the DO module).
Otherwise, a residual current can flow for a "0-signal" in the event of a current break.
130
Wiring Diagram of F-Switch PROFIsafe - Connection of Digital Outputs
WARNING
WARNING
ET 200pro Distributed I/O System - Fail-Safe Modules
Operating Instructions, 05/2007, A5E00394073-02