Fault Tracing - ABB ACS355 series User Manual

426 Appendix: Safe torque off (STO)

Fault tracing

The indications given during the normal operation of the Safe torque off function are
selected by parameter 3025 STO OPERATION.
The diagnostics of the Safe torque off function cross-compare the status of the two
STO channels. In case the channels are not in the same state, a fault reaction
function is performed and the drive trips on an "STO hardware failure" fault. An
attempt to use the STO in a non-redundant manner, for example activating only one
channel, will trigger the same reaction.
For the indications generated by the drive, see chapter Fault tracing, and for details
on directing fault and warning indications to an output on the control unit for external
diagnostics.
Any failures of the Safe torque off function must be reported to ABB.