0735

Common Causes

• Faulty DD encoder or DD encoder slave sensor on the reported axis
• Damaged encoder link cable or loose/corroded connector
• Failed inverter unit control board
• Noise or transmission errors on the encoder link (CRC, parity, format, time-out)

Troubleshooting Steps

1. 1Read the code number shown with the alarm: code YY=$00 = Error detected at the DD encoder; code YY=$01 = Error detected at the DD encoder slave sensor; code ZZZZ bit13 = Communication error with the DD encoder slave sensor; code ZZZZ bit12 = Communication error with the DD encoder; code ZZZZ bit11 = MT buffer error; code ZZZZ bit10 = Transmission loop error in AT mode; code ZZZZ bit9 = Data overrun in the receive section of the interface; code ZZZZ bit6 = Modulation code error
2. 2Read the code on screen: YY=$00 means the error was detected at the DD encoder itself, YY=$01 means at the slave sensor; ZZZZ is the link error status.
3. 3Interpret ZZZZ bits to narrow the fault — e.g. bit0 time-out, bit1 parity, bit5 CRC, bit6 modulation code, bit12 communication error with the DD encoder, bit13 communication error with the slave sensor.
4. 4Lock out power and allow the inverter DC bus to discharge, then inspect the encoder link cables and connectors on the reported axis for damage, coolant, or poor seating; reseat and retest.
5. 5If the cable and connectors are good, suspect the DD encoder (or slave sensor if YY=$01) and replace it.
6. 6If the alarm persists, the inverter unit control board is the remaining suspect — have it checked or replaced.
7. 7If it still returns, record the alarm number, full code, and axis and contact Okuma service.