2135

Common Causes

• Faulty DD encoder (or its slave sensor) on the indicated axis
• Damaged encoder link cable or loose/corroded connector
• Noise or wiring fault causing CRC, parity, or time-out errors on the link
• Defective inverter unit control board

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. 2Note the object (axis name or spindle) and the full code. YY=00 means the error was detected at the DD encoder itself; YY=01 points to the slave sensor.
3. 3Decode the ZZZZ status bits to identify the failure type: bit0 time-out or bit1 parity suggests cable/connector trouble; bit12/bit13 indicate lost communication with the encoder or slave sensor; bit5 CRC and bit4 format errors point to noise or a failing encoder.
4. 4Lock out the machine power, then inspect the encoder link cable and connectors on the flagged axis for bent pins, oil contamination, chafing, or loose seating; reseat and clean them.
5. 5Check cable routing for damage near moving parts and verify shielding/grounding is intact to rule out noise.
6. 6If the link error persists, substitute or test the DD encoder (or slave sensor if YY=01) on that axis.
7. 7If the encoder and cabling check out, the inverter unit control board is the remaining suspect; record the alarm number, code, and object and contact Okuma service before replacing it.