What causes FANUC alarm 284?

Part program contains an illegal G-code or M-code combination for this alarm type. Missing or incorrect address word in the program block. Axis or parameter value out of range for the commanded function. Required option not enabled on this CNC for the commanded function. Conflict between active modal states and the commanded function.

How do I fix FANUC alarm 284?

1. Note the block number shown on the alarm screen and locate that block in the program. 2. Review the command in that block against the Fanuc programming manual for alarm 284. 3. Check for missing address words, incorrect values, or conflicting G-code combinations. 4. Verify any required CNC options are enabled if using advanced functions. 5. Correct the program and verify the fix before restarting machining.

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FANUC Controller

Program/G-code · Intermediate · 5-30 minutes

Alarm 284

Fanuc 284 - Normal direction control data error

Alarm 284 occurs when the normal direction control data for tool orientation or workpiece surface normal vector is improperly specified in the part program. This is commonly seen in 5-axis machining programs or when using features like tool axis control (G43.4/G43.5) where the normal vector components are invalid, out of range, or mathematically undefined.

FANUCProgram/G-codeIntermediate5-30 minutes

284

Fanuc 284 - Normal direction control data error

NORMAL DIRECTION CONTROL DATA ERROR

Root Cause Summary

Alarm 284 occurs when the normal direction control data for tool orientation or workpiece surface normal vector is improperly specified in the part program. This is commonly seen in 5-axis machining programs or when using features like tool axis control (G43.4/G43.5) where the normal vector components are invalid, out of range, or mathematically undefined.

Safety

Verify corrected program or parameters before resuming machining

Causes and Fixes

1
Review the part program at the alarm line and locate any G43.4, G43.5, or G43.7 commands with I, J, K vector parameters.
2
Verify that I, J, K values form a valid direction vector where I²+J²+K² is non-zero. Standard unit vector should equal 1.0 (e.g., I0 J0 K1 for Z-axis).
Do not use I0 J0 K0 as this creates a zero-magnitude vector which is mathematically undefined
3
Check for missing vector components. All three (I, J, K) must typically be specified or use previous modal values correctly.
4
Simulate the program in memory mode or use the control's graphic verification to identify the exact block causing the error before running on the machine.

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