1138

Common Causes

• Faulty DD encoder
• Loose, damaged or contaminated encoder link cable or connector
• Encoder fuse supply voltage out of the normal 10.6-13.8 V range (short or wiring fault)
• Incompatible encoder parameters, protocol version or data format (YY=6)
• Defective inverter unit control board

Troubleshooting Steps

1. 1Read the code number shown with the alarm: code XX=0-7 = Initialization step at failure: 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. If XXYY = $FFFF, the encoder fuse voltage is abnormal (ZZZZ = measured value, 12 V = $9980, normal 10.6-13.8 V). Lock out power and check the encoder supply wiring and fuse for a short or overload before proceeding.
3. 3Note XX to see where initialization stopped (1 = network address setting, 2 = basic communication info request, 6 = position detection start). Failures at steps 1-3 point to the link hardware; steps 5-6 point to parameters or the encoder.
4. 4If YY = 0, 1, 2 or 3 (communication error or timeout), power down and inspect/reseat the encoder link connectors at the encoder and the inverter unit; check the cable run for pinching, chafing or coolant, and substitute a known-good cable if available.
5. 5If YY = 4 or 5, the encoder responded abnormally; for YY = 5 decode the embedded alarm code via MCS DD Encoder error (alarm 1136).
6. 6If YY = 6, ZZZZ identifies the parameter fault (1 = too few parameters received, 3 = multi-turn range over, 4/5/6 = protocol or data format incompatible); have Okuma service verify encoder parameters and software version compatibility.
7. 7If the link and parameters are good, replace the DD encoder; suspect the inverter unit control board last. If the alarm returns, record the full XXYYZZZZ code and contact Okuma service.