Abstract: A sensing device and a method for sensing the presence and absence of an object in a machine using the sensing device. The sensing device generally including a sensing mechanism, a resistive element, and a control mechanism communicatively coupled to the sensing mechanism and resistive element. The sensing mechanism being coupled to the resistive element. The method comprising actuating the sensing mechanism so that it senses the location of the object. Recording the voltage across the resistive element in the control mechanism when the sensing mechanism senses the location of the object. Reactuating the sensing mechanism at least one more time to sense the location of the object. Measuring a subsequent voltage across the resistive element when the sensing mechanism is reactuated and comparing the subsequent voltage with the recorded voltage across the resistive element when the resistive element sensed the location of the object.

Abstract: A sensing device for monitoring the presence of a tool or other object on an automatic machine comprises a sensing head adapted to be mounted on the machine. The sensing head has a sensing needle mounted on the output shaft of a reversible motor actuated on each cycle of the automatic machine for movement through a swing angle such that the sensing needle will either contact the monitored object or complete the full swing angle movement resulting in a cycle continue or cycle stop signal to the automatic machine control. The swing angle is manually adjustable by a setting ring on the sensing head for either clockwise or counterclockwise initial rotation of the sensing needle through any desired angle up to 180.degree. degrees.