FANUC Alarm PRIO-499 — Modbus System Error
FANUC PRIO-499 (“Modbus System Error”): Modbus TCP System Error. First check: Turn off the controller, then turn it on again.
Updated 2026-09-17 · LogrobotLM reference
Description
Modbus TCP System Error. A general system failure has occurred.
Remedy
Turn off the controller, then turn it on again. If the error still occurs, document the events that led to the error and contact your FANUC technical representative.
Related codes
Indicative field information — the robot manufacturer's manual and safety procedures always prevail. Never bypass a safety device; apply lockout/tagout (LOTO) before any physical intervention. How this reference is built →