What causes FANUC alarm 006?

Part program contains an illegal or malformed command related to the alarm condition. Missing required address word or parameter value in the program block. Programmed value is out of the allowable range. Conflict between active modal codes and the commanded function. Post-processor configuration mismatch for this Fanuc series.

How do I fix FANUC alarm 006?

1. Note the block number shown in the alarm screen and locate that block in the program. 2. Review the command in that block against the Fanuc programming manual. 3. Check for missing words, incorrect values, or conflicting G-code combinations. 4. Verify the program is post-processed for the correct Fanuc series. 5. Correct the program and dry-run at low speed before resuming machining.

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FANUC Controller

Program/G-code · Basic · 5-10 minutes

Alarm 006

Fanuc Alarm 006 - Invalid Negative Value

Fanuc Alarm 006 occurs when a negative value is specified in a G-code command or address where only positive values or zero are permitted. This typically happens with commands like feed rates (F), spindle speeds (S), tool numbers (T), M-codes, or specific address values that must be non-negative by definition in the Fanuc control specification.

FANUCProgram/G-codeBasic5-10 minutes

006

Fanuc Alarm 006 - Invalid Negative Value

Illegal Use of Negative Sign

Root Cause Summary

Fanuc Alarm 006 occurs when a negative value is specified in a G-code command or address where only positive values or zero are permitted. This typically happens with commands like feed rates (F), spindle speeds (S), tool numbers (T), M-codes, or specific address values that must be non-negative by definition in the Fanuc control specification.

Safety

Command will not execute

Causes and Fixes

1
Press RESET to clear the alarm and identify the program block number displayed with the alarm on the CRT screen.
2
Navigate to EDIT mode and search for the identified N-number or line. Examine all address codes in that block for negative signs (e.g., F-100, S-1200, T-05, M-03).
3
Remove the negative sign from the offending address code and ensure the value is positive or zero as required by the command specification.
4
Verify program syntax by running single block execution (SINGLE BLOCK switch ON) in MEM or MDI mode to confirm alarm is resolved.

DIY Feasiblehigh confidence

Call a technician if:

·System variables require modification beyond operator access level
·Alarm persists after correcting all visible negative signs

Prevention

Always use positive values for N, T, G, and M words
Validate programs using the CHECK function before execution
Use program templates with correct syntax structure

Common Mistakes

Copying programs from different control types without syntax verification
Manual typing errors when entering negative coordinates in wrong address fields
Confusion between coordinate values (which can be negative) and command codes (which cannot)

Related Alarms

002 003 007 010

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