Safe Operating Stop (Sos) - Siemens SINAMICS S120 Function Manual

4.2.6

Safe Operating Stop (SOS)

This function serves for failsafe monitoring of the standstill position of a drive.
Drive can be forced out of the SOS position by mechanical forces
A drive under position control can be forced out of the "Safe Operating Stop" (SOS)
position by mechanical forces that are greater than the maximum torque of the drive. This
unwanted drive movement then triggers a Category 1 Stop function according to EN 60204-
1 (fault response function STOP B). The alarms for SS1 and STO must be observed.
• If there is a hazard due to unwanted motion in your application, take measures to
Note
In particular, the motor is energized while the SOS function is performing position control.
• Ensure that the motor cannot be touched while it is in the SOS state.
● Drive stopping is monitored using an SOS tolerance window (p9530).
● Effect on "Speed setpoint limit effective" (r9733[0...2]):
If SOS is selected, setpoint 0 is specified in r9733[0...2].
Note
Size of the tolerance window
The size of the tolerance window should be slightly above the standard standstill monitoring
limit, otherwise the standard monitoring functions will no longer be effective.
Parameter r9731 displays the safe position accuracy (load side) that can be achieved as a
maximum, based on the acquisition of the actual value for the safe motion monitoring
functions.
STOP B is the stop response after the standstill tolerance window has been violated.
The SOS function comes into effect in the following cases:
● After SOS is selected and the delay time in p9551 has elapsed
The drive must be braked to standstill within this delay time, e.g. by the controller.
● As a consequence of SS2
● As a consequence of STOP C (corresponds to selection of SS2)
● As a consequence of STOP D (corresponds to selection of SOS)
● As a consequence of STOP E (corresponds to selecting SOS with additional activation of
the standard "Extended stop and retract (ESR)" function)
Safety Integrated
Function Manual, 12/2018, 6SL3097-5AR00-0BP1
WARNING
counter it, for example, by using a brake with safe monitoring. For additional information,
see Chapter "Safe Brake Control (SBC) (Page 78)".
Description of Safety Integrated functions
4.2 Safety Integrated Extended Functions
103