Allen-bradley Company, LLC

Theodore L Bernhard

Gregory L Merrell

Ernst H Dummermuth

Thomas M Hoch

Bruce S Jaffe

Associated with each processor in a multiprocessor numerical control system is a watchdog timer circuit which is periodically reset by its processor under normal operating conditions. If a malfunction should occur in one of the processors, its watchdog timer is not reset and it times out. A fault monitor line connects to each watchdog timer circuit and an emergency stop circuit, and when a malfunction occurs in any one of the processors, this condition is indicated to all the processors and to the emergency stop circuit.

Fault monitor for numerical control system

A numerical control system includes a main processor which performs such functions as interpolation and outputting of motion command signals to the servomechanisms on a machine tool. A separate programmable interface processor connects to the main processor bus structure and it operates as a programmable controller to control the discrete digital I/O devices associated with the machine tool. A third processor couples through a serial data link with the main processor and it operates to service peripheral I/O devices associated with the front control panel on the numerical control system.

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Mentor on the Lake, OH, United States of America

Theodore L Bernhard