What causes FANUC alarm 224?

The program is attempting to run an axis positioning command without first performing a reference (zero) return for that axis. The program is attempting to run a spindle positioning command without the spindle being in spindle positioning mode. A G28 (return to reference position) command is missing or incorrect in the program.

How do I fix FANUC alarm 224?

1. Check the program and ensure all axes that require a reference return have a G28 or other homing command before any positioning moves. 2. Verify the spindle is in positioning mode (M19) before any spindle positioning commands are issued. 3. Jog each axis to its reference position and perform a manual reference return (G28) to ensure the machine is properly homed. 4. Review the program logic and flow to identify where the missing reference return or spindle positioning mode command should be inserted. 5. If the issue persists, check for any mechanical problems with the reference switches or spindle positioning system. 6. Consult the Fanuc control manual and machine documentation for the proper procedures to set up reference returns and spindle positioning.

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FANUC Controller

Spindle · Intermediate · 30-60 minutes

Alarm 224

Fanuc Alarm 224 - ZERO RETURN NOT FINISHED

Alarm 224 occurs when the machine attempts to start automatic operation (AUTO mode or MDI) without completing a reference position return (homing) on all required axes, or when a spindle positioning command is issued to a spindle not currently in positioning mode. This is a safety interlock to ensure the CNC control knows the absolute machine position before executing programmed moves.

FANUCSpindleIntermediate30-60 minutes

224

Fanuc Alarm 224 - ZERO RETURN NOT FINISHED

SPINDLE ALARM 224

Root Cause Summary

Alarm 224 occurs when the machine attempts to start automatic operation (AUTO mode or MDI) without completing a reference position return (homing) on all required axes, or when a spindle positioning command is issued to a spindle not currently in positioning mode. This is a safety interlock to ensure the CNC control knows the absolute machine position before executing programmed moves.

Causes and Fixes

1
Check DIAGNOSIS screen for zero return completion status: Press SYSTEM > DIAGNOSIS > search for diagnostic number 300-307 (axis-specific). Bit 5 (ZRN) indicates zero return completion status for each axis. A value of 0 means zero return is NOT complete.
2
Verify parameter 1815 bit 0 (ZRN): Press SYSTEM > PARAM > search parameter 1815. If bit 0 = 1, zero return is required before automatic operation. Check parameter 1005 bits for each axis to confirm which axes require zero return (bit = 1 means axis requires homing).
3
Perform reference position return in MANUAL mode: Select JOG or HANDLE mode, press the REF RETURN (or ZERO RET) soft key, then manually move each required axis to the reference position using the axis direction keys. Observe the machine position display to confirm all axes show zero or reference position after completion.
Ensure the path to reference position is clear of obstructions. The machine will move at rapid traverse rate (parameter 1428) during the final approach to the reference position.
4
If zero return cannot be completed, check reference position switch operation: Access DIAGNOSIS screen > diagnostic 300-307 and monitor bit 1 (DGN) for grid/dog signal and bit 4 (ZP) for zero pulse signal during manual movement near the reference position. Both signals must be detected for successful zero return.

DIY Feasiblehigh confidence

Call a technician if:

·Encoder hardware failure
·Persistent parameter corruption
·Mechanical reference position problems

Prevention

Always complete reference return after power-on
Monitor absolute encoder battery status regularly
Avoid interrupting zero return sequences

Common Mistakes

Attempting AUTO mode before completing REF
Ignoring spindle positioning mode requirements
Incorrect parameter #1815 bit settings

Related Alarms

400 401 410 411

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