502

Press RESET to clear the alarm. Navigate to POSITION screen and verify current machine coordinate position for the faulted axis (n). Note the exact position value where the alarm occurred.

Access SYSTEM > PARAM and check Parameter 1320 (bit 5, STL2) to verify stored stroke check II is enabled. Then check Parameter 1322 for the affected axis - this contains the positive software limit value in machine coordinates.

Compare the position where alarm occurred against Parameter 1322 setting and the actual mechanical travel limits in the machine specifications. If Parameter 1322 is too conservative, adjust it to appropriate value after verifying mechanical clearances.

Changing Parameter 1322 requires parameter write enable (bit 0 of Parameter 3202). Ensure new limit does not exceed mechanical travel limits or risk collision damage.

If parameter is correct, review the NC program or MDI command that caused the overtravel. Check for incorrect G54-G59 work offset values (Parameters 5221-5226 series) or G52/G92 local coordinate system shifts that moved the working envelope beyond limits.

Check DIAGNOSIS screen > PARAMETER (#300 series) to verify current position feedback registers match displayed machine position. Navigate to DIAGNOSIS > SERVO to check servo alarm history and any abnormal servo status flags.

Inspect servo amplifier LED indicators on the axis drive unit. Verify no alarm LEDs are lit. For absolute encoders, check ABSOLUTE > MULTI-TURN screen to verify battery voltage is above 3.0V (displayed in DIAGNOSIS or SYSTEM screen depending on series).

If position data is corrupted or encoder battery is low, perform position reference point return (zero return). Power cycle the machine if necessary, then execute manual reference point return for the affected axis using G28 or manual zero return operation.

If absolute encoder battery failed, you must re-establish reference point. Position accuracy may be lost until proper zero return is completed.

Check encoder cable connections at both motor and amplifier. Inspect for damaged cables, loose connectors, or contamination. Verify encoder signal quality in DIAGNOSIS screen > SERVO parameters if available for your control series.

Navigate to OFFSET/SETTING > WORK OFFSET screen and verify all active work coordinate systems (G54-G59, G54.1 if applicable). Check that offsets for the faulted axis are within reasonable range and not inadvertently shifted to extreme values.

Check for active G52 local coordinate system or G92 coordinate system setting. Press POSITION button and toggle through coordinate systems (RELATIVE, MACHINE, WORKPIECE) to identify any unexpected offsets. G92 shifts are visible in the current coordinate display.

If G92 offset is active and incorrect, it can be canceled by executing G92.1 command in MDI mode. Verify Parameter 1202#6 (G92) setting determines G92 behavior. Review program for unintended G92 commands without corresponding cancellation.

G92 cancellation will change active coordinate system. Ensure machine position is safe before canceling offsets.

Reset work offsets to known good values or re-teach work coordinate systems. Verify Parameter 1220 (reference counter type) matches the machine configuration to ensure proper coordinate system calculation.