2139

Common Causes

• Faulty DD encoder slave sensor
• Loose, damaged or contaminated encoder link cable/connector between the sensor and inverter unit
• Encoder fuse voltage out of range (normal 10.6-13.8 V) indicating a short or wiring fault on the encoder supply
• Incompatible encoder parameters or communication protocol version (YY=6)
• Defective inverter unit control board

Troubleshooting Steps

1. 1Read the code number shown with the alarm: code XX=0-7 = Initialization step where it failed: 0 reset, 1 network address setting, 2 basic communication info request, 3 communication software version change, 4 device info acquisition, 5 parameter change, 6 position detection start, 7 AT mode start; code YY=0 = Communication error; ZZZZ shows encoder link error status C2ERR; code YY=1/2/3 = Transmission start, transmission finish or reception finish timeout; ZZZZ shows transmitted frame info QC2MTINF; code YY=4 = Abnormal response address; ZZZZ is the network address of the responding device; code YY=5 = Abnormal response code; ZZZZ is alarm code plus positional data status (see alarm 1136); code YY=6 = Parameter error; ZZZZ: 1 too few parameters received, 2 incompatible basic communication info, 3 multi-turn range over, 4 protocol version incompatible, 5 position data format incompatible, 6 abbreviated data mode incompatible; code XXYY=$FFFF = Abnormal encoder fuse voltage; ZZZZ is the measured voltage (12 V = $9980, normal 10.6-13.8 V)
2. 2Read the full code on screen. If XXYY shows $FFFF, the encoder fuse voltage is abnormal: ZZZZ is the measured value (12 V = $9980, normal 10.6-13.8 V). Lock out power, then check the encoder supply wiring and fuse for a short before anything else.
3. 3Note XX to see how far initialization got (1 = network address setting, 4 = device info acquisition, 6 = position detection start). Early-stage failures point to wiring/link hardware; later stages point to parameters or the sensor itself.
4. 4If YY = 0, 1, 2 or 3 (communication error or transmit/receive timeout), inspect and reseat the encoder link connectors at the slave sensor and at the inverter unit; check the cable for pinching, coolant ingress or bent pins, and swap the cable if a spare is available.
5. 5If YY = 4 or 5, the sensor responded abnormally; for YY = 5 look up the embedded alarm code under MCS DD Encoder error (alarm 1136) and follow that diagnosis.
6. 6If YY = 6, the code's ZZZZ gives the parameter fault (e.g. 3 = multi-turn detection range over, 4/5/6 = protocol or data format incompatibility); have Okuma service verify the encoder-related parameters and software compatibility.
7. 7If the link and parameters check out, replace the DD encoder slave sensor; only after that suspect the inverter unit control board. If the alarm returns, record the full XXYYZZZZ code and contact Okuma service.