7381

Encoder 1

ABB · ACS880

What does 7381 mean?

A feedback fault has occurred with Encoder 1. This can manifest during initial setup due to incorrect wiring, or after sustained operation due to damage, electromagnetic interference, or module failure. It results in a loss of accurate motor position/speed data, which is critical for precise motor control.

Common Causes

  • Broken or damaged wiring in the encoder cable (e.g., open circuit on A/B/Z signals, short to ground, intermittent connection).
  • Encoder power supply failure (e.g., loss of 5VDC or 15VDC at the encoder).
  • Loose or corroded connections at the drive's encoder input terminals (e.g., X20, X21) or at the encoder itself.
  • Incorrect encoder type or pulse count parameter settings (e.g., P21-01, P21-02) for the installed encoder.
  • Excessive electromagnetic interference (EMI) affecting signal integrity, especially on unshielded or poorly shielded cables.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Verify 5VDC or 15VDC power supply to Encoder 1 at its connector (e.g., pins 1 and 2) using a multimeter.

  2. 2

    Check continuity of all signal wires (A, /A, B, /B, Z, /Z) from Encoder 1 to the drive's input terminals (e.g., X20, X21).

  3. 3

    Inspect all terminals at the encoder and drive for looseness, corrosion, or signs of overheating.

  4. 4

    Confirm encoder parameters (e.g., P21-01 Encoder type, P21-02 Pulses per revolution) are correctly configured.

  5. 5

    Ensure encoder cable shielding is properly terminated and grounded at both the drive and motor end to mitigate EMI.

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Verified technical data. Last updated: March 2026

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