511
Negative Soft Stroke Limit Exceeded
Fanuc · Alpha i series AC Servo Motor
What does 511 mean?
The machine has exceeded its negative soft stroke limit, a software-defined boundary. This suggests improper parameter configuration for soft limits (No.143) or an invalid motion command, leading to an unexpected stop.
Common Causes
- Appropriate values have not been specified for parameter No.143
- An invalid move command has been specified
Repair Steps & Checklist
Click steps to track your progress.
- 1
Check whether appropriate values have been specified for parameter No.143
- 2
Check whether a valid move command is specified
- 3
Move the tool in the opposite direction in jog mode, then perform a reset
Verified technical data. Last updated: March 2026
Related Faults
Source: Fanuc Alpha i series AC Servo Motor