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

3.2.5

Safe Operating Stop (SOS)

Definition according to EN 61800-5-2:
"This SOS function is used for safe monitor-
ing of the standstill position of a drive."
Example of how the function can be used
Example
A protective door must only be opened if a motor is
in the safe standstill state.
The protected machine areas can be entered without having to shut down the machine as
long as SOS is active.
After SOS has been selected it becomes active after the parameterizable delay time has
expired. The drive must be braked to standstill within this delay time (e.g. by the controller).
Drive stopping is monitored using an SOS tolerance window. At the instant this function
becomes active, the current actual position is stored as the comparison position until SOS is
deselected again. Any delay time is cleared after SOS is deselected and the drive can be
immediately moved.
The drive is stopped with SS1 when the standstill tolerance window is violated.
Note
Contrary to SS1 and SS2, SOS does not automatically brake the drive
The control still enters the setpoint.
This means that in the user program of the control system, the system must respond to the
"SOS selected" bit so that the control system brings the drive to a standstill within the delay
time.
Safety Integrated
Function Manual, 12/2018, 6SL3097-5AR00-0BP1
Overview of Safety Integrated functions
3.2 Safety Integrated Extended Functions
Possible solution
Select SOS
•
A higher-level controller brakes the axis
•
(e.g. position-controlled) down to standstill
within the configured time between the se-
lection of SOS and when it becomes active.
Standstill is then safely monitored via the
•
SOS function.
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