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ErrorLib — Industrial Fault Code Library

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SP0027

Position Coder Disconnected

Fanuc · AC Spindle Motor Alpha i-Beta i Series Parameters

What does SP0027 mean?

The position coder (encoder) feedback cable is disconnected or the sensor is faulty. This results in loss of position feedback, making position control impossible.

Common Causes

  • Position encoder cable is physically disconnected.
  • Encoder signal lines are damaged.
  • The encoder itself has failed.
  • Incorrect encoder type configured in CNC.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Check physical connection of the encoder cable at both the motor and the amplifier.

  2. 2

    Measure encoder signal integrity (e.g., A, B, Z pulses) at amplifier terminals.

  3. 3

    Verify encoder resolution and type settings in CNC parameter P4-XX.

  4. 4

    Test encoder output using an oscilloscope if possible.

Browse all codes in this manual (60)
Verified technical data. Last updated: April 2026

Related Faults

749Serial Communication Error during Activation750Spindle Amplifier Not Activated (16i)PS0223Spindle Not Set for Control
Source: Fanuc AC Spindle Motor Alpha i-Beta i Series Parameters
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