3691

Common Causes

• Failed Rotary encoder 1 (internal signal amplitude or A/D offset fault)
• Contamination or damage inside the encoder affecting signal amplitude
• Encoder communication error (bit6 of the status byte set)
• Damaged encoder cable or connector causing signal degradation

Troubleshooting Steps

1. 1Read the code number shown with the alarm: code XX bit7 = Encoder alarm flag set; code XX bit6 = Encoder communication error; code 8X = Encoder output amplitude is normal; code 9X = Encoder output amplitude is small; code AX = Encoder output amplitude is large; code BX = Encoder output amplitude is far too small; code YY=00 = Encoder not started; code YY=01 = Stopped by stop command
2. 2Note the axis named in the alarm object and record the full code XXYYZZZZ shown on screen.
3. 3Read the YY portion: values 11-17 point to A/D offset voltage faults, 25-2F to signal amplitude faults, 80-FF to an encoder CPU fault, and 02 to an illegal control parameter inside the encoder.
4. 4Check the XX status byte: 8X means output amplitude is normal, while 9X/AX/BX indicate the amplitude is small, large, or far too small, confirming an encoder signal problem.
5. 5Inspect the encoder cable and connectors on the flagged axis for damage, oil ingress, or loose pins before condemning the encoder itself.
6. 6If the wiring is sound, replace Rotary encoder 1 as directed by the manual.
7. 7If the alarm returns after encoder replacement, record the alarm number, code and object and contact Okuma service.