Siemens SINAMICS S210 - Sequence Diagram; Selecting;Deselecting Safe Torque Off

STO facilitates personnel to work safely with the protective door open. A classic Emergency
Stop with electromechanical isolation is not required. The converter remains connected to the
line and can be fully diagnosed.
Note
The distinction between Emergency Off and Emergency Stop
"Emergency Off" and "Emergency Stop" are commands that minimize different risks in the
machine or plant.
The STO function is suitable for implementing an Emergency Stop - but not an Emergency Off.
Details regarding the distinction between Emergency Off and Emergency Stop are provided
in the following section:
What is the difference between the Emergency Off and Emergency Stop functions?
(Page 745)
Sequence diagram
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During operation, STO is selected via PROFIsafe or F-DI.
The converter signals the status to the PLC via PROFIsafe for further processing.
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After the response time, the drive immediately initiates safe pulse suppression. This interrupts the
torque-generating energy fed to the motor. The motor coasts down to a standstill. STO safely
prevents an unwanted restart of the motor.
Restart:
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The converter goes into the "Ready to start" state, when STO is deselected via PROFIsafe or F-
DI.
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The converter switches the motor on again with a positive signal edge at ON/OFF.
Selecting/deselecting "Safe Torque Off"
If "Safe Torque Off" is selected, the motor holding brake is closed (if connected and configured).
Safety functions integrated in the drive
4.2 Basic Functions
SINAMICS S210 servo drive system
Operating Instructions, 12/2017, A5E41702836B AA 59