Patent ID: 8310226

Claim:
A device for diagnosing signal status in measurement and control by a driven object, the device comprising: a voltage generating means for generating a pulse voltage and an alternating voltage, a measuring means of which a current, a voltage, or a resistance varies is changed, or a driven object which converts a change of state of a controlling object into a change of a current, a voltage, or a resistance, a rectifying circuit, and a transformer having a primary side connected to the voltage generating means, and a secondary side connected to the measuring means or the driven object through the rectifying circuit, wherein the transformer is an insulation transformer of which the primary side is insulated from the secondary side, a primary winding is provided with an intermediate tap, a current measuring means is connected to the intermediate tap to measure a current in the primary side of the transformer caused by a current flow in the driven object connected to the secondary side via the rectifying circuit, and a detection of a change in the current, the voltage, or the resistance of the driven object and an evaluation of soundness of a circuit are performed based on a measurement result of the current measuring means.