What causes FANUC alarm 312?

Incorrect G-code command or syntax in the program. Attempting to use a G-code command that is not supported by the Fanuc control. Incorrect or missing dimensions in the program's direct drawing dimensions section.

How do I fix FANUC alarm 312?

1. Review the program line by line and check for any G-code commands or syntax errors in the direct drawing dimensions section. 2. Verify that all the dimensions specified in the direct drawing dimensions section are valid and match the part drawing. 3. Check the Fanuc control's G-code reference manual to ensure the G-codes used in the program are supported by the control. 4. If the issue persists, try running the program in single block mode to identify the specific line causing the error. 5. Correct any issues found in the program and reload it into the Fanuc control. 6. If the error persists, contact the Fanuc technical support team for further assistance.

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FANUC Controller

Program/G-code · Intermediate · 30-60 minutes

Alarm 312

Fanuc Alarm 312 - ILLEGAL COMMAND IN DIRECT DRAWING DIMENSIONS PROGRAMMING

Alarm 312 occurs when the CNC detects an improper G-code or format during direct drawing dimension programming (DDD), typically using G50.1/G51.1 programming. This alarm is triggered when incompatible G-codes are specified within a DDD block, incorrect syntax is used for direct dimension input, or the drawing dimension coordinate system is improperly defined.

FANUCProgram/G-codeIntermediate30-60 minutes

312

Fanuc Alarm 312 - ILLEGAL COMMAND IN DIRECT DRAWING DIMENSIONS PROGRAMMING

ILLEGAL FORMAT IN DRAWING DIMENSION

Root Cause Summary

Alarm 312 occurs when the CNC detects an improper G-code or format during direct drawing dimension programming (DDD), typically using G50.1/G51.1 programming. This alarm is triggered when incompatible G-codes are specified within a DDD block, incorrect syntax is used for direct dimension input, or the drawing dimension coordinate system is improperly defined.

Causes and Fixes

1
Review the program block causing the alarm. Check for G-codes that are incompatible with G50.1/G51.1 DDD programming, particularly G68, G43/G44/G49, and canned cycle commands G73-G89.
2
Verify parameter 5400-5404 (Direct Drawing Dimension settings) are correctly set for your machine configuration. Access via SYSTEM > PARAM and check bit settings for DDD function enable.
3
Ensure G50.1 (DDD cancel) is commanded before any incompatible G-code. Restructure the program to execute coordinate transformations or compensation commands outside the G51.1 active block.
4
Check the program syntax: G51.1 format should be G51.1 X__ Y__ I__ J__ where X,Y define corner position and I,J define diagonal corner. Verify all four coordinates are specified when required.

DIY Feasiblehigh confidence

Call a technician if:

·DDD option not installed
·Parameter corruption suspected
·Control software issues

Prevention

Always verify DDD mode is active before using dimensional commands
Use proper dimension symbol formatting
Test DDD programs in single block mode first

Common Mistakes

Using circular interpolation in DDD blocks
Mixing standard and dimensional programming without mode changes
Incorrect dimension symbol character encoding

Related Alarms

310 311 313

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