Siemens SIRIUS 3RK3 Equipment Manual page 135

Insufficient safety function
Can Cause Death, Serious Injury, or Property Damage.
When safety-related outputs or inputs are used on a single channel, a cable cross-circuit or the
reaction of loads can result in a dangerous malfunction. When stringent requirements
regarding safety must be fulfilled, the risk of dangerous malfunctions must be minimized by
implementing appropriate measures (e.g., protected cable installation).
Note
To achieve SIL 2/3 per IEC 61508 or PL d/e per EN ISO 13849-1, a fault exclusion such as a short-
circuit to a power cable or ground is required. This can be implemented, for example, within a
cabinet and by installing the connection cables in such a way that they are protected. If that is
not possible, the outputs must be implemented with two channels. For this purpose, separate
cables must be laid to actuators/contactors. In the associated function element "F output," the
output type "F output redundant" must be chosen.
SIRIUS 3RK3 Modular Safety System
Equipment Manual, 07/2020, NEB926253002000/RS-AC/006
WARNING
Description of the hardware
5.3 Connecting / wiring
135