Safety functions 191
Step Description
1 The SDI positive request is received (for example, from the I/O). The motor rotates into
the forbidden direction (in this case, negative). The drive starts to decelerate the motor
speed to zero speed. SAR1 parameter 200.112 defines the deceleration ramp. The
FSO module starts the ramp monitoring (SAR1 parameters SARx.21, SARx.22). The
SDI active indication is off.
Note: If parameter 200.112 has value 0, the drive (parameter 23.23) defines the ramp.
2 The motor speed reaches zero and the motor stops. The FSO stops the ramp
monitoring and starts the SDI monitoring according to the SDI tolerance limit degree
(not shown in this figure, see section SDI with correct rotation direction on page 186).
The SDI active indication goes on.
2b If the deceleration of the motor does not follow the ramp monitoring limits, the FSO
module activates the STO function and the motor coasts to a stop. The STO indication
goes on (parameter STO.21). See section Safe torque off (STO) on page 67 for more
information on how to configure the STO function.
3 The user gives a new speed reference. The motor starts to rotate into the correct
(positive) direction.
3b Zero speed limit (A) reached. If the STO function was activated at 2b, the STO
acknowledgement becomes allowed and the FSO starts the SDI monitoring.
4 The SDI request is removed and the FSO stops the SDI monitoring. The SDI function is
acknowledged (automatic SDI acknowledgement) and the SDI active indication goes
off.
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