Fanuc Series 0i Error Code 411

Fanuc PLC & VFD Major Servo

Model: Series 0i | Code: 411

Applicable Systems
Series 0i Series 16/18/21 Alpha Beta

Symptoms

The CNC system displays alarm 411: SERVO ALARM: n-TH AXIS - EXCESS ERROR (MOVE). The position deviation value when the axis is moving is larger than the set value. The axis is lagging significantly behind the commanded position during motion.

Possible Causes

  • Excessive load or friction preventing the axis from keeping up with the commanded speed
  • Servo motor power or torque insufficient for the load during high-speed moves
  • Amplifier or motor degradation causing reduced torque output
  • Maximum feed rate parameter set too high for the mechanical system

Troubleshooting Steps

  1. Step 1: Check the actual feed rate against the commanded feed rate on the CNC diagnostic screen
    If the actual speed is consistently lower than commanded, the motor or amplifier may be underpowered
  2. Step 2: Inspect the mechanical axis for increased friction or binding
    Disconnect the motor and check if the axis moves freely; check lubrication
  3. Step 3: Verify the servo motor and amplifier match the machine builder's specification
    If a motor or amplifier was replaced, verify the replacement matches the original
  4. Step 4: Check the maximum feed rate and acceleration parameters
    If parameters were changed (e.g., after a battery replacement), reset to the builder's documented values

How to Reset

To reset: 1) Press RESET. 2) Reduce the feed rate or fix the mechanical issue. 3) Re-run. Caution: Excess error during movement can cause poor surface finish and dimensional inaccuracy in machining.

Frequently Asked Questions

  • Q: How is alarm 411 different from 410?

    Alarm 410 occurs when the axis is stopped and drifting (excess error at stop). Alarm 411 occurs when the axis is moving and cannot keep up with the commanded position (excess error during movement). The causes and troubleshooting approaches are different.

  • Q: What is the typical excess error threshold?

    The threshold is set by the machine tool builder in parameters. For a typical machining center, the moving excess error limit is around 100-300 microns. Exceeding this triggers alarm 411.

Related Fanuc Fault Codes

Source: FANUC Series 0i-Mate Maintenance Manual, B-64115EN

Category: PLC & VFD