ABB ACS880-14, Hardware Manual

Page: 227 / 248

Fault tracing
The indications given during the normal operation of the Safe torque off function are selected
by drive control program parameter
31.22 .
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.
See the firmware manual of the drive control program for the indications generated by the
drive, 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.
The Safe torque off function 227