Which statement about MAJOR ALARMS is true?

• A. They begin with 4xxx
• B. They begin with 5xxx-7xxx
• C. They begin with 1xxx, 2xxx, and 3xxx, and servo power is off until reset
• D. They begin with 1xxx and 2xxx only

Answer: (C)

Major alarms in Motoman controllers are indicated by diagnostic codes in the 1xxx, 2xxx, and 3xxx ranges. When one of these alarms occurs, the robot’s servo power is automatically turned off and remains off until the fault is reset. This behavior prevents any movement while the fault is unresolved, providing a safety mechanism and ensuring the issue is acknowledged and addressed before re-arming the system. After diagnosing and correcting the problem, you reset the alarm to clear the fault, then you can re-enable servo power and resume operation. Codes outside this 1xxx–3xxx range correspond to other types of warnings or conditions, not the major-alarm class described here.