FANUC codes
FANUCOvertravel/LimitBasic5-15 minutes

500

Fanuc Alarm 500 - X Axis Positive Overtravel

Overtravel +X

Stored stroke check alarm. The axis has exceeded the stored stroke limit +X as defined in parameter 1320-1327.

Root Cause Summary

Fanuc Alarm 500 occurs when the machine attempts to move beyond the positive software travel limit (stored stroke limit) on the specified axis. This is triggered when the commanded position exceeds the value set in parameter No. 1326 (positive side stored stroke limit). The alarm protects the machine from physical damage by halting motion before hardware overtravel occurs.

Safety

  • Jog slowly away from limit
  • Verify position after recovery

Causes and Fixes

  1. 1

    Navigate to POSITION screen and note the current Machine Coordinate position of the alarmed axis. Compare this value against parameter No. 1326 (positive stored stroke limit) found at SYSTEM > PARAM > search for parameter 1326.

  2. 2

    Verify parameter No. 1320 bit 0 (SLS) is set to 1 to enable stored stroke check. If bit 0 = 0, the stored stroke check is disabled and alarm should not occur. Check SYSTEM > PARAM > 1320.

    Parameter modification requires parameter write enable (PWE) bit 1 in parameter 0000 to be set. Turning PWE on/off requires machine restart.

  3. 3

    Review the active work coordinate offset (G54-G59) at OFFSET/SETTING > WORK screen and tool length offset at OFFSET/SETTING > TOOL OFS screen. Calculate total commanded position: Machine Zero + Work Offset + Tool Offset + Programmed Position.

  4. 4

    If program is correct, adjust parameter No. 1326 for the affected axis to a larger positive value within safe machine travel limits. Verify mechanical hard limits via parameter No. 1321 (+OT) are not exceeded.

    Always confirm physical machine travel capability and proximity switch locations before increasing software limits. Exceeding mechanical limits can cause crash damage.

DIY Feasiblehigh confidence

Call a technician if:

  • ·Parameter 1320 doesn't match machine specifications
  • ·Reference return fails repeatedly
  • ·Physical limit switches malfunctioning

Prevention

  • Always verify work offsets after setup changes
  • Implement program simulation before first run
  • Regular calibration of tool offset values
  • Document parameter 1320 settings for each machine

Common Mistakes

  • Forgetting to account for tool length in travel calculations
  • Setting work offsets without considering machine limits
  • Not performing reference return after power interruption
  • Copying programs between machines with different travel limits

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