Siemens SINUMERIK 840D sl Function Manual page 59

● The selection/deselection of the STO function also acknowledges the safety faults when
the Basic Functions are used. The standard acknowledgment mechanism must also be
performed.
● The signals of the components connected at the terminals (e.g. pushbuttons, switches, ...)
can be debounced in order to prevent false tripping due to signal disturbances. The filter
times are set using parameters p9651 and p9851.
Undesirable motor motion
Appropriate measures must be taken to ensure that the motor does not move once the motor
power supply has been disconnected ("coast down") (e.g. enable the "Safe Brake Control"
function for a vertical axis).
Danger as a result of brief, limited motion
If two power transistors in the Motor Module fail at the same time (one in the upper and one
in the lower bridge of the inverter), this can cause brief, limited movement. The maximum
movement can be:
● Synchronous rotary motors: Max. movement = 180° / pole pair number
● Synchronous linear motors: Max. movement = pole width
● The status of the Safe Torque Off function is displayed using parameters.
Enabling the Safe Torque Off function
The Safe Torque Off function is enabled via the following parameters:
● STO via terminals:
– (p9601.0 = 1, p9801.0 = 1)
Selecting/deselecting Safe Torque Off
Safe Torque Off is selected as follows:
● 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 safe acknowledgment. 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 prompt "Close motor holding brake" is canceled.
● Any active STOP F or STOP A commands are canceled (see r9772 / r9872).
● The messages in the fault memory must also be reset using the general acknowledgment
mechanism.
Safety Integrated
Function Manual, 12/2017, 6FC5397-4BP40-6BA1
WARNING
WARNING
Safety Functions integrated in the drive
5.3 Safe Torque Off (STO)
59