0739

Common Causes

• Faulty DD encoder (slave sensor)
• Encoder link cable or connector damaged, loose, or poorly seated
• Abnormal voltage at the encoder fuse (code XXYY=$FFFF indicates fuse voltage outside the 10.6–13.8 V normal range)
• Incompatible or corrupted encoder parameters / communication basic information (YY=6)
• Inverter unit control board fault

Troubleshooting Steps

1. 1Read the code number shown with the alarm: code XX=0 = Failure during reset step of encoder link initialization; code XX=1 = Failure during network address setting; code XX=2 = Failure requesting basic communication information; code XX=3 = Failure during communication software version change; code XX=4 = Failure acquiring device information; code XX=5 = Failure during parameter change; code XX=6 = Failure at position detection start; code XX=7 = Failure at AT mode start
2. 2Read the full code XXYYZZZZ on the alarm screen. XX shows which initialization step 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); YY shows the error type.
3. 3If XXYY reads $FFFF, the encoder fuse voltage is abnormal: ZZZZ is the detected voltage ($9980 = 12 V; normal 10.6–13.8 V). Check the encoder power supply and fuse before anything else.
4. 4Power down and lock out the machine, then inspect and reseat the encoder link cables and connectors between the DD encoder and the inverter unit; look for bent pins, coolant ingress, or chafed cable.
5. 5If YY=6 (parameter error), ZZZZ identifies the parameter problem (e.g. 1 = insufficient parameters received, 3 = multi-turn detection range over, 4/5/6 = protocol, data format or abbreviated data mode incompatibility) — have the encoder parameter set verified against the correct values for this sensor.
6. 6If YY=5, ZZZZ carries an alarm code and positional data status; cross-reference MCS DD Encoder error alarm 1136 for the detailed meaning.
7. 7If cables, connectors and supply voltage are good, replace the DD encoder (slave sensor); only after that suspect the inverter unit control board. If the alarm persists, record the full XXYYZZZZ code and contact Okuma service.