Patent ID: 7911967

Claim:
A control and monitor signal transmission system, comprising: a single master station connected to a common data signal transmission line and comprising a master-station transmission circuit, the master-station transmission circuit comprising a timing signal generator that generates a timing signal; a plurality of slave stations, each of the slave stations being connected to the common data signal transmission line and comprising a slave-station transmission circuit, the slave-station transmission circuit comprising a timing signal generator that generates a timing signal; a controller connected to the master station; and a plurality of controllable apparatuses associated with the plurality of slave stations, each of the controllable apparatuses being connected to one of the slave stations and comprising a controllable unit and a sensor that monitors the controllable unit, wherein control data from the controller is transmitted to the controllable units of the controllable apparatuses via the common data signal transmission line, and monitor data from the sensors is transmitted to the controller; the timing signal generator of the master-station transmission circuit generates a predetermined timing signal that synchronizes with a signal of a clock having a predetermined cycle; under the control of the timing signal, the master-station transmission circuit modifies a duty ratio of a negative voltage-level period relative to a neutral electric potential of a predetermined pulse and a duty ratio of a positive voltage-level period relative to a neutral electric potential of a subsequent pulse in accordance with each data value of a control data signal from the controller for each cycle of the clock so as to convert the control data signal to a serial pulse voltage signal, and outputs the serial pulse voltage signal to the data signal transmission line; and under the control of the timing signal, the master-station transmission circuit detects a monitor data signal superimposed on the serial pulse voltage signal transmitted through the data signal transmission line by detecting a presence or absence of a signal of a current flowing during the negative voltage-level period relative to the neutral electric potential of the predetermined pulse and a presence or absence of a signal of a current flowing during the positive voltage-level period relative to the neutral electric potential of the subsequent pulse for each cycle of the clock so as to extract each data value of the serial monitor data signal, and converts the data value of the serial monitor data signal into the monitor data.