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ErrorLib — Industrial Fault Code Library

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91

Communication timeout bus module – MOVIMOT®

SEW Eurodrive · Drives

What does 91 mean?

The communications link between the fieldbus interface (MFP/MFI) and the MOVIMOT® inverter is interrupted or experiences a timeout. This system fault is signaled to the PLC as error code 91 dec via the diagnostics channel or status words, and typically triggers a steady 'SYS-F' LED light on the fieldbus interface.

Common Causes

  • Interrupted or faulty electrical communication link between the fieldbus interface (MFP/MFI) and the MOVIMOT® inverter.
  • Missing 24 V supply to the MOVIMOT® inverter.
  • Maintenance switch on the field distributor is set to OFF.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Check and re-establish the electrical communication link between the fieldbus interface (MFP/MFI) and the MOVIMOT® inverter (e.g., verify connections at terminals RS+ and RS-).

  2. 2

    Verify the 24 V electronics supply voltage to the MOVIMOT® inverter.

  3. 3

    Check the setting of the maintenance switch on the field distributor to ensure it is in the ON position.

Browse all codes in this manual (39)
Verified technical data. Last updated: April 2026

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Source: SEW Eurodrive Drives
Open Manual (Page 118)Search more codes in this manual