Safety arrangement for NC systems

摘要

An arrangement for monitoring the operation of a numerically controlled machine tool in which a motor drives an encoder whose pulses represent the angular displacement of the motor. Counters respond to the drive signal from the numerical control to the motor and the sensing signal resulting from the encoder to provide a first detection signal in the event of a deviation between the drive and sensing signals while additional counters are responsive to the numerical controller for generating a second detection signal when the extent of drive of the motor is not reached. From these detection signals, an error signal is derived.