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72 Safety functions
Step Description
1
The STO request is received (for example, from the I/O). The FSO activates the drive
STO and starts counters for times A and C. STO active indication parameter STO
output (STO.21) goes on.
2
After time C has elapsed, the acknowledgement becomes allowed as soon as the STO
request has been removed (step 5).
3
After time A has elapsed, the FSO activates the SBC (brake) and starts a counter for
time B.
4
After time B has elapsed, the FSO module defines the motor as stopped and the STO
completed indication goes on.
5
The STO request is removed.
6
After the acknowledgement, the STO and SBC functions are deactivated, and the
control is given back to the drive, which controls the brake from now on. The indications
STO output (STO.21) and STO completed output (STO.22) go off.
With an encoder
Motor speed
STO.13
C
A
1
A
Zero speed with encoder (parameter FSOGEN.52): Speed limit at which the motor has
stopped, the safety function is completed and STO completed indication (parameter
STO.22) goes on.
B
SBC delay (parameter SBC.12): Time from the activation of the drive STO function to the
moment when the FSO activates the SBC function (brake). In this case, the value is
positive and the FSO activates the SBC after the drive STO. If the value is zero, the FSO
activates the SBC and drive STO functions at the same time. Note: It is possible to set
the SBC delay so that the SBC is activated while the motor is still rotating.
SBC.12
B
2
3
4
6
5
STO request
Drive STO state
& indication
SBC output
STO completed
indication
Time
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