BONFIGLIOLI Agile Series Application Manual Functional Safety page 22

Truth table
In the truth table, the states of the safety-relevant inputs STOA and STOB for activa-
tion and deactivation of the safety function STO are listed.
STOA
0
0
1
1
5-second monitoring
It will be checked if the two inputs STOA or STOB are switched on within an interval
of less than 5 sec for requesting the release of the frequency inverter output stages.
If function STO is triggered by removing one of the signals from inputs STOA or
STOB, the status changes to "STO triggered" and the output stage is inhibited. In this
state the monitoring function checks, that during the next 5 seconds the second input
is switched off. If this has not been done within 5 s after occurrence of this state, an
error is triggered (5-second monitoring).
− Different signal states on inputs STOA or STOB start the 5-second monitoring
− Within 5 seconds, the same signal must be present of both inputs, otherwise an
error will be signaled (F1205)
If the STO function is triggered on one channel, in the next following 5 s the STO
−
function must be triggered on both channels.
The error F1205 can be acknowledged using the Fault reset to reset the drive.
Behavior of frequency inverter after start
− Initialization
− Monitoring for release request (5-second monitoring)
− Preparation of release (check of stop paths)
− Release of frequency inverter
Behavior of frequency inverter in the case of an error
− Switch off of IGBT in power output stage by disconnection of optocoupler supply
voltage
− Suppression of control pulses of IGBT
− Setting of error bit with possibility of transfer to overriding controller
− Setting of digital output for error message
− Release of digital input for error acknowledgement.
22
STOB
Safety function "Safe Torque Off" (STO) has been triggered. The
0 frequency inverter signals no error in STO function. The inverter
release is interrupted.
STO is triggered. Monitoring for error in frequency inverter or ex-
1
ternal circuitry (5-second monitoring). After 5 seconds, an error is
signaled.
0
The inverter release is interrupted.
STO is not triggered. Release for operation.
1 Only in this state starting signals are accepted by the frequency
inverter and lead to a switching of the modulation.
Truth table
Description of state
AGL-STOV0-01SV0-05
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