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ErrorLib — Industrial Fault Code Library

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E5

SI-T Watchdog Error

Yaskawa · F7 Drive

What does E5 mean?

This fault indicates a consistency error in received control data or a synchronization problem between the master controller and the Drive when using an SI-T option card. It signifies a breakdown in reliable communication, which can lead to unpredictable Drive behavior or complete loss of control. Such errors require immediate attention to restore stable operation.

Common Causes

  • Loss of communication or intermittent connection between the master controller (e.g., PLC, HMI) and the SI-T option card.
  • Incorrect communication parameters (e.g., baud rate, parity, address) configured on either the master controller or the SI-T card (parameters C5-01 to C5-05 for Modbus).
  • Excessive electrical noise on the communication bus preventing reliable data transmission and causing watchdog timeout.
  • Firmware mismatch or corruption on the SI-T option card or the Drive's main control board.
  • Hardware failure of the SI-T option card itself, affecting its ability to process or receive data consistently.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Verify the physical integrity of the communication cable (e.g., Ethernet, RS-485) connected to the SI-T option card for loose connections or damage.

  2. 2

    Check the communication parameters (e.g., C5-01 to C5-05 for serial communication) in the Drive and on the master controller to ensure they match precisely.

  3. 3

    Use a network diagnostic tool (e.g., Wireshark for Ethernet/IP) to monitor traffic on the communication bus for dropped packets or errors.

  4. 4

    Isolate the SI-T option card by powering down the Drive, removing, and re-inserting the card to ensure proper seating.

  5. 5

    Update the Drive's firmware, which may include updates for the SI-T option card, to resolve potential software bugs.

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

Related Faults

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