0882

Common Causes

• Motor encoder (BL motor) or PG/magnetic encoder (VAC motor) malfunction producing erratic position counts
• Damaged encoder link cable or connector causing corrupted feedback
• Axis actually over-traveled: code 1, 2 or 3 indicates a linear, rotary, or limited axis exceeded its travel range
• Faulty inverter unit control board misreading the feedback

Troubleshooting Steps

1. 1Read the code number shown with the alarm: code 1 = A linear axis exceeded its travel range; code 2 = A rotary axis exceeded 360 degrees of travel, or a limited axis holds negative position data; code 3 = A limited axis exceeded its travel range
2. 2Read the code on screen: Code 1 means a linear axis exceeded its travel range, Code 2 a rotary axis passed 360 degrees or a limited axis has negative position data, Code 3 a limited axis exceeded its travel range; any other number is the magnitude of the encoder value change per control cycle, pointing to feedback trouble rather than real motion.
3. 3For Codes 1-3, check whether the axis named in the object physically ran to or past its stroke end, and move it back inside the travel range before investigating further.
4. 4For large numeric codes, lock out power and let the drive discharge, then inspect the encoder link cable and connectors on the named axis (motor encoder on BL motors, PG/magnetic encoder on VAC motors) for loose seating, bent pins, coolant, or chafing; reseat and clean first.
5. 5If the cable is sound, substitute or replace the encoder itself, since erratic counts from a failing encoder are the most common hardware cause.
6. 6Only after encoder and cable are eliminated should the inverter unit control board be suspected and replaced.
7. 7If the alarm returns after these checks, record the alarm number, code and object and contact Okuma service.