Appendices
A - 102
AC Servomotors/Servo Drives 1S-series with Built-in EtherCAT® Communications User’s Manual (I586)
08430000 1-rotation Counter 
Error
The encoder detected a 
one-rotation counter error.
• There is excessive noise
• Failure due to vibration, 
impact, condensation, for-
eign matter, etc.
√ P. A-123
08440000 Overspeed Error The encoder detected the 
overspeed.
• The motor was rotated by 
external forces
• Encoder failure and false 
detection
√ P. A-124
08450000 Encoder Memory 
Error
The encoder detected a 
non-volatile memory error.
• False detection due to a 
data read error that was 
caused by excessive noise
• Non-volatile memory failure
• Encoder failure
√ P. A-124
08460000 Absolute Position 
Detection Error
The encoder detected a 
multi-rotation counter error.
• A detection error was 
detected in the multi-rota-
tion detection section of the 
encoder
• There is excessive noise
√ P. A-125
08480000 Main Power Supply 
Undervoltage (insuf-
ficient voltage 
between P and N)
The main circuit power sup-
ply voltage fell below the 
operation guarantee range 
during Servo ON.
• Incorrect wiring of the main 
circuit power supply
• The low power supply volt-
age is applied to the Servo 
Drive
• The long time was set in 
Momentary Hold Time and 
the voltage was decreased 
momentarily
• Servo Drive failure
√ P. A-126
08490000 Overcurrent Error The current flowing to the 
motor exceeded the protec-
tion level.
• There is a short-circuit, 
ground fault, or contact fail-
ure on the U, V, or W motor 
cable
• There is a short-circuit on 
the wiring of External 
Regeneration Resistor
• The insulation resistance 
failed between the U, V, or 
W motor cable and the 
motor ground wire
• False detection due to the 
noise
• Servo Drive failure
√ P. A-127
084A0000 Encoder Communi-
cations Disconnec-
tion Error
The communications dis-
connection was detected 
between the encoder and 
the Servo Drive.
• Noise into the encoder 
cable 
• Contact failure of the signal 
line, and disconnection of 
the encoder 
• Power supply undervoltage 
to the encoder
• Encoder failure
√ P. A-128
Event code 
(hex)
Event name Description Assumed cause
Level
Refer-
ence
Min
Obs
Info