F109-50

Difference level RS485 driver 1. Fault Faulty "B" or "Cycle" signal

SEW Eurodrive · MOVIDRIVE MDX60B/61B Variable Speed Drive

What does F109-50 mean?

A fault is detected in the RS485 driver 1, specifically with the 'B' or 'Cycle' signal. This is usually caused by no encoder connection or an incorrect encoder type being connected.

Common Causes

  • RS485 communication line 'B' or 'Cycle' signal is missing or corrupted.
  • Faulty transceiver on the RS485 interface.
  • Cable defect or poor termination on RS485 bus.
  • Interference affecting the RS485 signal integrity.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Check encoder connection.

  2. 2

    Check encoder cabling.

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Verified technical data. Last updated: March 2026

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Source: SEW Eurodrive MOVIDRIVE MDX60B/61B Variable Speed Drive