What is a typical cause of an 'unexpected stop' or motion fault and how is it resolved?

• A. Software license expiry; renew license.
• B. Tool length mismatch; recalibrate tool.
• C. Mechanical obstruction or I/O fault; resolve by clearing the obstruction/fault, then reattempt.
• D. Frame configuration error; reselect frame.

Answer: (C)

Unexpected stops and motion faults usually come from something physically blocking the robot’s path or from an I/O fault that triggers a protective stop. When the controller detects an obstruction or an I/O irregularity, it halts motion to keep people and equipment safe and raises an alarm. The way to resolve it is to safely clear the obstruction or fix the faulty I/O condition, then reset the alarm and reattempt the move. After clearing, check that the work area is free, safety interlocks are engaged, and the I/O signals are back to their correct states. If the issue recurs, inspect the mechanical path, wiring, and sensors for damage and verify tooling and frames are reporting proper data before trying again.