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ErrorLib — Industrial Fault Code Library

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Sd4

Encoder fault at X9

Lenze · 4800/4900 Series

What does Sd4 mean?

This fault indicates a problem with an encoder connected to terminal X9 on the drive. This could be due to wiring issues, a faulty encoder, or mechanical damage. By default, this critical condition triggers a full TRIP, inhibiting all ignition pulses and resetting the Ready signal, as encoder feedback at this input is crucial for motor control. Manual reset is required.

Common Causes

  • Broken wire or loose connection in the encoder cable connected to drive terminal X9.
  • Short circuit between encoder signal lines (A/B/Z, /A//B//Z) or to ground/power at terminal X9.
  • Incorrect encoder type selected in drive parameters (e.g., P5-01 set for incremental when SSI is connected).
  • Faulty encoder hardware, generating no pulses or distorted signals.
  • Insufficient or incorrect encoder supply voltage (e.g., 5VDC or 24VDC) from the drive at terminal X9.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Power off the drive and disconnect the encoder cable at terminal X9.

  2. 2

    Check for +5VDC or +24VDC supply voltage at the encoder power pins of terminal X9 from the drive.

  3. 3

    Use a multimeter to check for continuity of each signal wire (A, /A, B, /B, Z, /Z) and power supply lines from the encoder to the drive connector.

  4. 4

    With an oscilloscope, observe the A, B, and Z encoder signals at the drive's X9 terminals while manually rotating the motor shaft. Look for clean square waves.

  5. 5

    Verify P5-01 (Encoder type selection) matches the installed encoder (e.g., incremental, SSI, absolute).

Browse all codes in this manual (31)
Verified technical data. Last updated: April 2026

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Source: Lenze 4800/4900 Series
View Official PDFSearch more codes in this manual