Siemens SIMATIC S7-300 Product Information page 200

Safety Integrated Functions in
SINAMICS Drive Systems
6.5 Behavior and reactions in the user program
Safe Stop 2 (SS2)
When SS2 is selected, the drive independently decelerates on the OFF3 ramp
speed-controlled and enters the monitored standstill (SOS). The drive then decouples
itself from the setpoint interface of the T-CPU.
Response in the user program
When SS2 is selected (displayed in StatuswordSafety.SS2_Active=TRUE (DBx 140.2)),
the current motion on the axis will be aborted (CommandAborded=True at the motion job
and error ID 8040 in the TO DB) and set to automatic follow-up mode. The automatic
follow-up mode should prevent triggering of the following error monitoring during the
OFF3 ramp autonomously performed by the drive.
When SS2 is deselected (StatuswordSafety.SS2_Active=FALSE), standstill monitoring in the
drive will be terminated. If no other safety function is active, the axis can be traversed again.
CAUTION
When SS2 is selected, MC_Power.Status=FALSE.
You cannot start motion jobs and they will be rejected with an error.
The removal of MC_Power.Enable while SS2 is selected results in the reaction configured
with Release_Disable. The drive coasts to a standstill.
Safe Operating Stop (SOS)
When SOS is selected, the drive continues to follow the setpoint interface and activates the
standstill monitoring after the delay time configured in the drive.
Response in the user program
When SOS is selected (displayed in StatuswordSafety.SOS_Selected=TRUE (DBx 140.3)),
the drive will be brought to a standstill within the configured time (p9351/p9551) and kept
there.
When SOS is deselected, the standstill monitoring in the drive will be deactivated;
the drive can traverse again without restriction provided no other safety function is active.
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Connection of the SINAMICS S120 to the Technology CPU
Product Information, 09/2011, A5E00480378-04