Installation manual
Publication 1394-IN002B-EN-P — February 2004
4-8 Troubleshooting Status Indicators
Axis Module Faults
Use the table below for troubleshooting axis module faults.
Fault Message
RSLogix (HIM):
Description: Potential Cause is: Possible Resolution is:
No Fault Message 
(condition indicated 
by on-screen 
message)
(Ax: ATune Flt)
Auto tune procedure failed 
to complete successfully.
Motor or feedback device malfunction.
• Check motor power/feedback wiring.
• Refer to on-screen message for resolution.
No Fault Message 
(condition indicated 
by on-screen 
message)
(Axis x Hookup 
Fault)
Hookup procedure failed to 
complete successfully.
Motor or feedback device malfunction.
• Check motor power/feedback wiring.
• Refer to on-screen message for resolution.
DriveHardFault
(Axis x Unknown)
Active when serial ring 
detects unknown axis 
module.
Unknown axis module.
• Check the slider connections.
• Replace the axis module.
AuxFeedbackFault
(Ax: Aux Fdbk AQB)
Auxiliary Encoder State 
Error
Auxiliary encoder has encountered an illegal 
state transition.
• Use shielded cables with twisted pair 
wires.
• Route the feedback away from potential 
noise sources.
• Check the system grounds.
• Replace the motor/encoder.
AuxFeedbackFault
(Ax: Aux Fdbk Comm)
Drive unable to 
communicate with 
auxiliary Smart feedback 
device.
The auxiliary encoder feedback signal is lost.
• Check auxiliary feedback wiring.
• Reset faults.
AuxFeedbackFault
(Ax: Aux Fdbk Loss)
The feedback wiring is 
open, shorted, or missing.
Open or short circuit has occurred on feedback 
wiring.
Check the feedback cable connectors/wiring 
to the system module and motor.
The feedback wiring or termination to system 
module is incorrect.
Check the feedback cable connectors/wiring 
to the system module and motor.
Motor feedback failure. Replace the motor feedback.
AuxFeedback 
NoiseFault
(Ax: Aux Fdbk Noise)
Excessive noise detected 
on feedback signals.
Poor grounding.
• Check ground clamp connectors.
• Check system module grounding.
DriveUndervoltage 
Fault
(Ax: Bus Loss)
The DC bus supply to the 
axis module was lost.
The slider connections may not be secure. Check slider connections.
An axis module’s bus link fuse has blown. Replace the axis module.
DriveOvercurrent 
Fault
(Ax: Desat)
Too much current in the 
axis module.
Power module malfunction. Replace the axis module.
DriveEnableInput 
Fault
(Drive Enable Flt)
Missing Drive Enable Input 
Signal
• An attempt was made to enable the axis 
through software while the Drive Enable 
hardware input was inactive.
• The Drive Enable input transitioned from 
active to inactive while the axis was enabled.
• Disable the Drive Enable Input fault.
• Verify that Drive Enable hardware input is 
active whenever the drive is enabled 
through software.










