What causes FANUC alarm 073?

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 073?

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 073

Fanuc Alarm 073 - Duplicate Program Number

Fanuc Alarm 073 occurs when attempting to register or transfer a program into CNC memory that has a program number (O-number) identical to an existing program already stored in memory. This is a memory management protection feature that prevents accidental overwriting of existing programs without explicit deletion or overwrite permission.

FANUCProgram/G-codeBasic5-10 minutes

073

Fanuc Alarm 073 - Duplicate Program Number

Program Number Already Used

Root Cause Summary

Fanuc Alarm 073 occurs when attempting to register or transfer a program into CNC memory that has a program number (O-number) identical to an existing program already stored in memory. This is a memory management protection feature that prevents accidental overwriting of existing programs without explicit deletion or overwrite permission.

Safety

Will not overwrite existing

Causes and Fixes

1
Press RESET to clear alarm 073. Navigate to EDIT mode, press PROG button, and search for the program number in question using the address search (O____). Verify if the program already exists in memory.
2
If the existing program can be deleted, select it and press DELETE soft key followed by EXEC (O DELETE). On some systems use PROGRAM > DELETE or the DELETE key while program is displayed.
Ensure the program being deleted is not currently in use or required for production. Make backup copies if necessary.
3
Check Parameter 3202 bit 6 (O8/O9). When set to 1, duplicate O-numbers are prohibited. If overwriting is regularly needed, coordinate with production management to set this bit to 0, then reboot the CNC (power cycle required for parameter change).
Disabling duplicate protection removes safeguards against accidental program overwriting. Establish shop-floor procedures to prevent unintended program loss.
4
After deletion or parameter change, retry program registration. For DNC/RS-232 transfer, re-send the program. For manual input, re-enter the program starting with the O-number.

DIY Feasiblehigh confidence

Call a technician if:

·Parameter 3202 corruption or unexpected values
·Memory hardware issues preventing program deletion
·System-level program protection that cannot be overridden

Prevention

Establish program numbering conventions and communicate to all operators
Regularly backup and clean program memory
Set parameter 3202 bit 6 for automatic program number increment
Use program management software to track program numbers

Common Mistakes

Not checking program directory before transfer
Forgetting to update subroutine calls when changing main program numbers
Attempting to overwrite protected programs without proper authorization
Using random program numbers without systematic approach

Related Alarms

074 078 079 080

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