Patent attributes
An output module for a PLC includes an output circuit. This output circuit is open or closed selectively between a power supply terminal (to which a power supply voltage is supplied) and an output terminal (connected to a solenoid). The output module includes a control apparatus which controls the operation of the output circuit. The output circuit includes switches connected in series to each other between the power supply terminal and the output terminal, and a current output section which performs an operation of short-circuiting terminals of the switch to pass a predetermined current through a path formed due to the short-circuiting. The control apparatus includes on/off control sections which controls on/off states of the respective switches, and diagnosis sections which perform a diagnosis on presence of a short-circuit fault in the respective switches based on diagnostic signals output from a low-potential terminal of the switches.
