Alarm 5

System Alarm: Feedback Mismatch, Semi-Closed Loop Error, or Current Offset Error

Fanuc · αi Series Servo Amplifier

What does Alarm 5 mean?

This alarm can indicate multiple issues depending on the set bits. If the OFS bit is set, it is a Feedback Mismatch alarm, suggesting opposite move directions for the position and velocity detectors. Other bits include MCC for Excessive Semi-Closed Loop Error and LDM for Current Offset Error.

Repair Steps

  1. 1

    If the OFS bit is set (Feedback mismatch alarm), check the rotation direction of the separate detector.

  2. 2

    If the separate detector's direction is opposite to the motor's rotation: For a Phase A/B detector, reverse the A and __A connections.

  3. 3

    If the separate detector's direction is opposite to the motor's rotation: For a Serial detector, reverse the signal direction setting for the separate detector.

  4. 4

    For Series 90B0/07 and subsequent editions, verify the setting that allows the signal direction to be reversed even for the phase A/B detector.

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Verified technical data. Last updated: March 2026
Source: Fanuc αi Series Servo Amplifier