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

5.5

Safe Operating Stop (SOS)

General description
This function serves for fail-safe monitoring of the standstill position of a drive.
Personnel can enter the protected machine areas without having to shut down the machine
as long as SOS is active.
Drive standstill is monitored by means of an SOS tolerance window (p9330 and p9530).
The SOS function is activated after SOS is selected and when the delay time set in
p9351/p9551 expires. The drive must be braked to standstill within this delay time (e.g. by
the controller). When this function is activated, the current actual position is saved as a
comparative position, until SOS is deselected again. Any delay time is cleared after SOS is
canceled and the drive can start up immediately.
Figure 5-4
Functional features of "Safe Operating Stop"
● The drive remains in the closed-loop control mode.
● A programmable standstill tolerance window is available.
● STOP B is the stop response after SOS has responded
Note
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 due to the acquisition of the actual value for the safe motion monitoring functions.
Safety Integrated
Function Manual, (FHS), 11/2009, 6SL3097-4AR00-0BP0
Standstill tolerance
Safety Integrated Extended Functions
5.5 Safe Operating Stop (SOS)
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