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ErrorLib — Industrial Fault Code Library

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CPF09

CPU-ASIC Mutual Diagnosis Fault

Yaskawa · F7 Drive

What does CPF09 mean?

Control circuit failure or damage involving a mutual diagnosis fault between the CPU and ASIC. This is a critical internal hardware fault affecting the core processing units and indicates a severe internal malfunction.

Common Causes

  • Communication link failure (e.g., SPI, I2C bus) between the main CPU and the ASIC on the control board.
  • One of the core processing units (CPU or ASIC) has an internal fault preventing proper self-diagnosis exchange.
  • Timing synchronization issues between the CPU and ASIC, leading to misinterpretation of diagnostic signals.
  • Unstable power supply or clock signals affecting either the CPU or ASIC's ability to communicate reliably.
  • Physical damage, contamination, or solder joint failure on the control board affecting the CPU-ASIC interface.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Power cycle the drive, ensuring a full power-off period (e.g., 60 seconds) to allow all internal components to reset.

  2. 2

    Inspect the drive's main control board carefully for any visible signs of damage, burn marks, or loose components near the CPU and ASIC.

  3. 3

    Verify the stability and correct levels of all internal regulated power supplies (e.g., 3.3V, 5V) at accessible test points.

  4. 4

    Check for excessive electromagnetic interference within the control panel by measuring ambient magnetic fields with an appropriate meter.

  5. 5

    Temporarily remove any optional interface cards to rule out conflicts or additional noise sources affecting the internal bus.

Browse all codes in this manual (63)
Verified technical data. Last updated: April 2026

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3021Speed Search Retry ErrorBUSCommunication Bus FaultBUS Option Com ErrOption Communication Error
Source: Yaskawa F7 Drive
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