FANUC codes
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FANUC Controller

Program/G-code · Advanced · 1-3 hours depending on root cause

Alarm 1001

Fanuc Alarm 1001 - AXIS CONTROL MODE ILLEGAL

Fanuc Alarm 1001 AXIS CONTROL MODE ILLEGAL occurs when the CNC detects an invalid or conflicting axis control mode setting, typically during mode changes or after parameter modifications. This alarm indicates that parameter settings related to axis control (position loop, servo control type, or mixed control mode) are incompatible or incorrectly configured for the current operation.

FANUCProgram/G-codeAdvanced1-3 hours depending on root cause

1001

Fanuc Alarm 1001 - AXIS CONTROL MODE ILLEGAL

AXIS CONTROL MODE ILLEGAL

Fanuc PS1001: An illegal axis control mode combination was commanded. The axis control mode requested is not compatible with the current machine state or the axis is already in a conflicting control mode.

Root Cause Summary

Fanuc Alarm 1001 AXIS CONTROL MODE ILLEGAL occurs when the CNC detects an invalid or conflicting axis control mode setting, typically during mode changes or after parameter modifications. This alarm indicates that parameter settings related to axis control (position loop, servo control type, or mixed control mode) are incompatible or incorrectly configured for the current operation.

Safety

  • Verify corrected values
  • Verify all corrected values maintain required machining accuracy
  • Before making any changes to the CNC program or control parameters, back up the existing program and parameters.
  • Verify all corrected values carefully to avoid unexpected machine behavior or collisions.
  • After making changes, run the program in single-block mode with the feed rate override set low to observe the machine's movements.
  • Be aware of potential mechanical hazards during program execution. Ensure the work area is clear of obstructions.
  • If adjusting parameters, be aware of the potential for unexpected machine behavior. Consult the CNC control's documentation before making changes.
  • If the machine exhibits erratic behavior, immediately press the emergency stop button.

Causes and Fixes

  1. 1

    Navigate to SYSTEM > PARAM and check parameter 1006 for each axis. Verify bit settings match axis configuration: bit 0 (position switch), bit 1 (mixed control). Values must be 0 or 1, not undefined.

  2. 2

    Check parameter 1815 (Servo Control Type) and 1820 (Position Coder Selection). Ensure settings align with actual feedback device configuration (encoder type, absolute/incremental, dual feedback setup).

    Mismatched encoder settings can cause axis runaway. Verify physical hardware before changing these parameters.

  3. 3

    Verify parameter 1800 series (1801-1832) servo motor codes match installed motors. Cross-reference motor model numbers with Fanuc servo motor parameter tables in Maintenance Manual.

  4. 4

    After parameter correction, power cycle CNC completely (turn OFF for 10 seconds). Clear alarm with RESET button and perform controlled axis movement test in JOG mode at 1% override.

DIY Feasiblehigh confidence

Call a technician if:

  • ·Parameter corruption suspected
  • ·Repeated alarms after corrections
  • ·System memory errors

Prevention

  • Validate program coordinates before loading
  • Use parameter input verification
  • Implement macro variable range checking
  • Regular backup of offset and parameter data

Common Mistakes

  • Entering imperial values in metric mode
  • Copy-pasting coordinates without format checking
  • Ignoring decimal point parameter settings
  • Using excessive precision in offset values

Related Alarms

1002100310101011

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