Encoder Loss

What does F091 mean?

One of the two required encoder channel signals (e.g., Channel A or B for differential encoders) is missing. This deprives the drive of accurate feedback on motor speed or position, leading to unstable control, position errors, or complete shutdown in applications requiring precise motion control.

Additional Steps

Steps 1–2 are listed in Priority Fix.

1. 3

   Check the encoder's power supply and ensure it is receiving the correct voltage.

2. 4

   If wiring is verified, replace the encoder unit as it may be internally faulty.