Siemens Sinamics S120 Function Manual page 466

Safety Integrated basic functions
9.4 Safe Torque Off (STO)
Appropriate measures must be taken to ensure that the motor does not undesirably move
once the energy feed has been disconnected, e.g. against coasting down or for a
hanging/suspended axis, the "Safe Brake Control" (SBC) function should be enabled, also
refer to Chapter "Safe Brake Control".
If two power transistors simultaneously fail in the power unit (one in the upper and one in
the lower bridge), then this can cause brief momentary movement.
The maximum movement can be:
• Synchronous rotary motors: Max. movement = 180 ° / No. of pole pairs
• Synchronous linear motors: Max. movement = pole width
● The status of the "Safe Torque Off" function is displayed using parameters (r9772, r9872,
Enabling the "Safe Torque Off" function
The "Safe Torque Off" function is enabled via the following parameters:
● STO via terminals:
● STO via PROFIsafe:
● STO via PROFIsafe and terminals:
Selecting/deselecting "Safe Torque Off"
The following is executed when "Safe Torque Off" is selected:
● Each monitoring channel triggers safe pulse suppression via its switch-off signal path.
● A motor holding brake is closed (if connected and configured).
Deselecting "Safe Torque Off" represents an internal safety acknowledgement. The following
is executed if the cause of the fault has been removed:
● Each monitoring channel cancels safe pulse suppression via its switch-off signal path.
● The Safety requirement "Close motor holding brake" is canceled.
464
WARNING
CAUTION
r9773 and r9774).
p9601.0 = 1, p9801.0 = 1
– p9601.0 = 0, p9801.0 = 0
– p9601.2 = 0, p9801.2 = 0
– p9601.3 = 1, p9801.3 = 1
– p9601.0 = 1, p9801.0 = 1
– p9601.2 = 0, p9801.2 = 0
– p9601.3 = 1, p9801.3 = 1
Function Manual, (FH1), 01/2012, 6SL3097-4AB00-0BP2
Drive functions