Safe Operating Stop (Sos) - Siemens SINUMERIK Series Function Manual

2.3.4

Safe Operating Stop (SOS)

Definition
Definition according to EN 61800-5-2:
"The function is used to safely monitor the standstill position of a drive."
SOS selection
Example of how the function can be used
● Dangerous areas of the machine can be entered without having to disconnect the power
to the drives.
● Vertical axes are held in position without a brake.
How does SOS function in detail?
This function serves for fail-safe monitoring of the standstill position of a drive. The protected
machine areas can be entered without having to shut down the machine as long as SOS is
active.
Drive stopping is monitored using an SOS tolerance window. When this function is activated,
the actual position is saved as a comparative 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, 10/2015, 6FC5397-3EP40-5BA3
SOS
Overview of Safety Integrated functions
2.3 Safety Integrated Extended Functions
33