Monarch NICE900 Door Operator Common Faults: Er20 Rotary Encoder Fault

Fault Symptoms: The door operator reports Er20 immediately upon movement; weak closing/opening, and the door running uncontrollably.

First, confirm the encoder model: This driver only supports open-collector ABZ phase encoders. Incremental and differential encoders cannot be used. If the model is incompatible, replace it with the corresponding encoder.

Railway Troubleshooting: Power off and check the encoder power cable and A/B/Z phase signal lines for broken wires, reversed polarity, and water damage/oxidation of the plug.

Practical Points: After wiring, restart the door operator and re-perform the motor angle self-learning.