FANUC codes
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FANUC Controller

Program/G-code · Basic · 5-15 minutes

Alarm 347

Fanuc Alarm 347 - TOOL CHANGE ILLEGAL COMMAND IN SAME BLOCK

Fanuc Alarm 347 occurs when the CNC detects multiple tool change commands (M06) or conflicting tool selection/change operations within a single NC program block. This is a programming error where the part program violates the fundamental rule that only one tool change operation can be executed per block.

FANUCProgram/G-codeBasic5-15 minutes

347

Fanuc Alarm 347 - TOOL CHANGE ILLEGAL COMMAND IN SAME BLOCK

SYSTEM ALARM 347

Fanuc alarm 347: SYSTEM ALARM 347. This alarm indicates a fault condition detected by the Fanuc control. Refer to the alarm number and name to identify the specific system or function involved.

Root Cause Summary

Fanuc Alarm 347 occurs when the CNC detects multiple tool change commands (M06) or conflicting tool selection/change operations within a single NC program block. This is a programming error where the part program violates the fundamental rule that only one tool change operation can be executed per block.

Causes and Fixes

  1. 1

    Navigate to the program screen (EDIT or MEM mode), press the ALARM key, and verify the exact block number causing alarm 347.

  2. 2

    Review the flagged block for duplicate M06 codes or multiple T-code/M06 combinations (e.g., 'T01 M06 T02 M06' or 'M06 M06').

  3. 3

    Edit the program to separate tool changes into individual blocks. Proper format should be one block with T-code, followed by a separate block with M06 (e.g., 'N100 T01;' then 'N110 M06;').

  4. 4

    Reset the alarm (RESET key), return to program start or correct block, and perform dry run to verify proper tool change sequence execution.

DIY Feasiblehigh confidence

Call a technician if:

  • ·Parameter corruption suspected
  • ·Custom macro programming beyond operator skill level
  • ·ATC mechanical issues preventing proper tool change sequence

Prevention

  • Always program one tool change command per block
  • Use program verification before running new programs
  • Implement standardized tool change macro templates
  • Regular backup of working programs before modifications

Common Mistakes

  • Copying/pasting tool change blocks without editing T codes
  • Mixing manual and automatic tool change commands
  • Not understanding macro program tool change interactions
  • Forgetting to separate T code from M06 command

Related Alarms

346348090091

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