Functional safety
FUNCTIONAL SAFETY
Examples
9.
317
DDS
HARDWARE
Ref.1310
Considerations to bear in mind in the previous examples
The auxiliary 24 V DC power supply must be independent from the
power controlled by external main contactor - KM1.
To achieve PL d or SIL 2, the safety controller must check the feed-
back of the STO safety function; i.e. the feedback of the Drive Enable
(state of the internal contact through AS1- AS2) and the feedback of
external main contactor - KM1 (status of the KM1 contact) at all the re-
quests of the STO safety function.