Siemens SINAMICS G120C Operating Instructions Manual page 72

Installing
4.8 Connecting the inverter
Further wiring options for digital inputs
Connection of contacts switching to P potential
Connection of contacts switching to N potential
68
with an external power source
with an external power source
If you want to connect the potential of the
external power source to the potential of
the inverter's internal power supply, you
must connect "GND" to terminals 34 and
69.
Connect terminals 69 and 34 to each other.
Operating Instructions, 07/2015, FW V4.7 SP3, A5E34263257B AC
SINAMICS G120C converter