1135

Common Causes

• Faulty DD encoder (or its slave sensor) on the reported axis
• Damaged encoder link cable or loose/corroded connector between encoder and inverter
• Failed inverter unit control board
• Electrical noise or a broken shield causing CRC, parity, or time-out errors on the link

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-over error in the interface receiving section; 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 it was detected at the DD encoder slave sensor - this tells you which sensor head to inspect.
3. 3Decode the ZZZZ status bits to narrow the fault: bit0 time-out or bit1 parity points to wiring/connectors; bit5 CRC or bit4 format errors point to noise or a failing encoder; bit12/bit13 indicate loss of communication with the encoder or slave sensor.
4. 4Lock out the machine and allow the drive to discharge, then inspect and reseat the encoder link cable connectors at both the encoder and inverter ends; check for bent pins, coolant ingress, and chafed cable along the axis run.
5. 5If the cable and connectors are good, substitute or replace the DD encoder (or slave sensor if YY=01) on the reported axis.
6. 6If the alarm persists with a known-good encoder and cable, the inverter unit control board is the remaining suspect - contact Okuma service with the alarm number, object, and full code.