What causes fault code AB-1756-MOTION1 (ControlLogix Servo Axis Fault — Motion Group Error)?

Position error exceeded tolerance — axis could not follow commanded profile. Motor feedback (encoder/resolver) signal lost — cable or connector issue. Drive hardware fault — overvoltage, overcurrent, or overtemperature on Kinetix drive. Motor winding fault — phase imbalance or ground fault detected by drive. Mechanical obstruction — axis cannot physically move to commanded position. Motion group update rate too fast for number of axes configured

How do I fix fault code AB-1756-MOTION1?

In Studio 5000, check Axis Properties > Faults tab for the specific axis fault code and timestamp. Check Kinetix drive display for local fault code — cross-reference with Kinetix manual. Inspect motor feedback cable — check connectors at motor and drive end, look for damage. Check for mechanical obstruction — manually move axis (if safe) to verify free travel. Clear the axis fault using MASR (Motion Axis Stop and Reset) instruction or through Axis Properties. If position error, check tuning gains — reduce velocity and acceleration commands. Monitor axis following error during normal operation — trending upward means mechanical wear or tuning drift

ControlLogix Servo Axis Fault — Motion Group Error

AB-1756-MOTION1

A Kinetix servo axis in a ControlLogix motion group has faulted. The motion group has stopped all coordinated axes. Common on Kinetix 5500/5700 servo drives.

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Probable Causes (ranked)

Position error exceeded tolerance — axis could not follow commanded profile
Motor feedback (encoder/resolver) signal lost — cable or connector issue
Drive hardware fault — overvoltage, overcurrent, or overtemperature on Kinetix drive
Motor winding fault — phase imbalance or ground fault detected by drive
Mechanical obstruction — axis cannot physically move to commanded position
Motion group update rate too fast for number of axes configured

Fix Steps

1 In Studio 5000, check Axis Properties > Faults tab for the specific axis fault code and timestamp
2 Check Kinetix drive display for local fault code — cross-reference with Kinetix manual
3 Inspect motor feedback cable — check connectors at motor and drive end, look for damage
4 Check for mechanical obstruction — manually move axis (if safe) to verify free travel
5 Clear the axis fault using MASR (Motion Axis Stop and Reset) instruction or through Axis Properties
6 If position error, check tuning gains — reduce velocity and acceleration commands
7 Monitor axis following error during normal operation — trending upward means mechanical wear or tuning drift

Field Trick

When a servo axis trips on following error, check the motor feedback cable FIRST. A flaky encoder connection causes intermittent position jumps that look like following errors. Wiggle the feedback cable connector at the motor while watching the position in Studio 5000 — if it jumps, replace the cable.

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