Siemens SINAMICS G120 Function Manual page 147

Description of the SDI function
Time response
If you select SDI, the inverter limits the speed or velocity setpoint to a value of zero in the
inhibited direction of rotation.
Figure 5-24
Delay time
The inverter monitors the direction of rotation of the motor after the delay time has expired.
When SDI is selected, the delay time must be longer than the time that the motor requires to
brake the maximum load from maximum speed down to standstill. The inverter brakes the
motor with the OFF3 ramp-down time.
Tolerance
The inverter permits brief motion in the monitored direction, for example for brief speed
overshoots after braking down to standstill. To do this, the inverter converts the motor speed
into an angle. With the tolerance, you limit the maximum permissible angle in the monitored
direction.
Safety Integrated - SINAMICS G110M, G120, G120C, G120D and SIMATIC ET 200pro FC-2
Function Manual, 04/2014, FW V4.7, A5E34261271B AA
Delay time and tolerance
Commissioning
5.7 Setting extended functions
147