1183

Common Causes

• Synthetic offset data for the full-closed loop encoder missing or set incorrectly
• Faulty ABSO SCALE or shaft-type position encoder
• Excessive lost motion: motor not rigidly tied to the moving part (loose coupling between motor and ball screw)
• Slipping or broken shaft drive belt
• Position loop gain set too high causing instability

Troubleshooting Steps

1. 1Read the code number shown with the alarm: code count = Number of times the encoder mismatch has been detected
2. 2Note the axis named in the alarm object and the code, which counts how many times the mismatch has been detected; a rising count points to progressive mechanical slip.
3. 3With power off, check the coupling between the motor and ball screw on the named axis for looseness, and inspect the shaft belt for slip, glazing, or breakage; retighten or replace as needed.
4. 4Check for excessive lost motion: jog the axis and watch whether the moving part responds immediately to motor rotation; backlash or free play indicates a mechanical disconnect.
5. 5Verify the synthetic offset data set for the full-closed loop encoder is present and correct for this axis.
6. 6If the mechanical drive is sound, suspect the ABSO SCALE or shaft position encoder itself; inspect its mounting and connections before replacing it.
7. 7If all hardware checks pass, the positional loop gain may be set too high; have Okuma service review the gain setting, and report the alarm number, axis, and detection count.