{"id":"ur-c263a21","model_id":"C263A21","name":"C263A21 Index Mark Validation Failed","summary":"The absolute motor encoder position cannot be validated because the joint encoder's calculated motor position is invalid. The code includes a signed value.","study_notes":[],"safety_notes":[],"sources":[{"url":"https://www.universal-robots.com/manuals/EN/HTML/SW5_26/Content/prod-err-codes/topics/CODE_263.html","title":"C263 Motor Encoder","accessed":"2026-10-26"}],"verification":{"status":"source_checked","checked_at":"2026-10-26","values":4,"method":"llm_source_check"},"updated_at":"2026-10-26","type":"alarm","spec":{"code":"C263A21","controllers":["universal-robots-e-series-control-box"],"meaning":"Validation of the detected index mark failed because the motor position calculated by the joint encoder is invalid, so the absolute motor encoder position cannot be validated.","remedy":"Perform a complete reboot sequence, update the software, or contact your local Universal Robots service provider for assistance."},"url":"https://machineschema.com/alarm/ur-c263a21","license":"https://creativecommons.org/licenses/by/4.0/"}