4691

Common Causes

• Failed Rotary encoder 1 (internal electronics or signal degradation)
• Encoder signal amplitude too small or too large due to contamination, gap change, or damaged read head
• AD offset voltage drift inside the encoder
• Damaged encoder cable or connector causing communication errors

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 XX=8X = Encoder output amplitude is normal; code XX=9X = Encoder output amplitude is small; code XX=AX = Encoder output amplitude is large; code XX=BX = Encoder output amplitude is too small; code YY=00 = Encoder not started; code YY=01 = Stopped by stop command
2. 2Note which axis is named in the alarm object, then read the code: the first byte (XX) is the encoder status (bit7 = alarm, bit6 = communication error; 8X = amplitude normal, 9X = amplitude small, AX = amplitude large, BX = amplitude too small).
3. 3Read the second byte (YY) for the specific encoder fault: e.g. 02 = illegal control parameter, 0E = synchronization mistake, 0F = illegal excitation output, 11-17 = AD offset voltage decrease/rise on A and/or B face, 25-2F = signal amplitude excessive or underestimated, 80-FF = encoder CPU fault.
4. 4If YY shows an amplitude or offset fault, inspect the encoder mounting area for coolant, oil, or chips contaminating the encoder, and check that the encoder cable and connector on that axis are seated and undamaged before condemning the unit.
5. 5If the status byte shows a communication error (bit6), check the encoder cable run and connectors for that axis for damage or poor contact.
6. 6The manual's corrective action is to replace Rotary encoder 1; after the above checks confirm the encoder itself is faulty, replace it with power off and locked out.
7. 7If the alarm returns with a new encoder, record the alarm number, full XXYYZZZZ code, and axis name and contact Okuma service.