Siemens SINAMICS G120 Function Manual page 210

Operation
6.7 Safe Speed Monitor (SSM)
The inverter immediately switches off the motor with the OFF2 command.
If the "SSM active" feedback signal should remain active when the pulses are inhibited, then
the inverter safely switches off the motor torque using the safety function STO.
Figure 6-34
210
OFF2 command when the SSM safety function is active
Safety Integrated - SINAMICS G110M, G120, G120C, G120D and SIMATIC ET 200pro FC-2
Function Manual, 04/2014, FW V4.7, A5E34261271B AA