Safety functions 83
Step Description
1 The SS1 request is received (for example from the I/O). The FSO starts a counter for
time A. SS1 state indication parameter SS1 output (SS1.21) goes on.
2 After time C has elapsed, the drive starts to ramp down the motor speed. SAR1
parameter 200.112 defines the deceleration ramp.
Note: If parameter 200.112 has value 0, the drive (parameter 23.23) defines the ramp.
3 The motor speed reaches the zero speed limit (B), the FSO activates the drive STO
function and STO active indication parameter STO output (STO.21) goes on. The SS1
completed output indication (parameter SS1.22) goes on and the acknowledgement
becomes allowed as soon as the SS1 request has been removed (step 4).
Note: If the SBC is configured in the STO function (see section Safe torque off (STO) on
page 67), also the SBC is activated (not shown in the figure).
• If the STO SBC delay (parameter SBC.12) is negative, the SBC is activated here and
the drive STO after this delay.
• If the STO SBC delay is positive or zero, the SBC and drive STO functions are
activated at the same time.
Note: You can define an extra delay (parameter SS1.15) before the FSO activates the
drive STO (and SBC, if used) (not shown in the figure).
3b If the drive has not ramped down fast enough when time A has elapsed, the FSO
activates the STO function. See section Safe torque off (STO) on page 67 for more
information on how to configure the STO function.
4 The SS1 request is removed.
5 After the acknowledgement, the STO and SS1 functions are deactivated. The
indications SS1 output (SS1.21), SS1 completed output (SS1.22), and STO output
(STO.21) go off.
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