Siemens SINUMERIK Series Function Manual page 135

When configuring the TM54F, SLS selection bit 0 is permanently set to "1", i.e. "statically
inactive" The inputs for the TM54F can be assigned as follows:
Input
F-DI 0
F-DI 1
F-DI 2
F-DI 3
Safety Integrated
Function Manual, 10/2015, 6FC5397-3EP40-5BA3
Function
Emergency stop, deselection of SS1
Deselection of SOS
(Safe Operating Stop)
Activation of SLS bit 1
(SLS bit 0 is permanently 1)
Safe acknowledgement - for the acknowledgement of safety alarms, if
acknowledgeable.
This F-DI may not have level "1" continuously.
Commissioning - application example
6.1 Planning
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