Patent ID: 8289128

Claim:
A monitoring system comprising a controller, a plurality of sensors, a plurality of alarms, and a plurality of input/output devices; wherein each input/output device is connected between the controller and one of the plurality of sensors or one of the plurality of alarms, each input/output device comprises an input circuit, an output circuit, and a connector, the input circuit and the output circuit are connected between the controller and the connector, the connector is further selectively connected to one of the plurality of sensors or one of the plurality of alarms and a DC power in series; and wherein the controller controls a status of the input circuit and the output circuit, upon the condition that the connector is connected to the alarm, the input circuit does not operate, the controller outputs a motion signal to the alarm via the output circuit; upon the condition that the connector is connected to the sensor, the output circuit does not operate, the sensor outputs a detection signal to the controller via the input circuit; wherein the input circuit comprises a first MOSFET, a first diode, a second diode, and a first relay, a gate of the first MOSFET is connected to a first terminal of the controller, a source of the first MOSFET is grounded, a drain of the first MOSFET is connected to an anode of the first diode, a cathode of the first diode is connected to a power source; wherein the first relay comprises a first coil, a first switch, and a second switch, a first terminal of the first coil is connected to the power source, a second terminal of the coil is connected to the drain of the MOSFET, a first terminal of the first switch is connected to a first terminal of the connector, a second terminal of the first switch is connected to a cathode of the second diode, an anode of the second diode is connected to the power source, a first terminal of the second switch is connected to a second terminal of the connector, a second terminal of the second switch is connected to a second terminal of the controller.