Siemens SINAMICS G120 Function Manual page 58

Installing
4.3 Activation via F-DI
The inverter provides the supply voltage
Connect the 24 V supply of the inverter to the sensors and connect the reference potentials
of the inputs used to GND.
The 24 V supply is not required when using the G110M "24 V Power Module" option
1
)
Figure 4-10
58
Connecting electromechanical sensors to the inverter power supply in series
Safety Integrated - SINAMICS G110M, G120, G120C, G120D and SIMATIC ET 200pro FC-2
Function Manual, 04/2014, FW V4.7, A5E34261271B AA