Abstract: A method and an installation permit the electronis transmission of data between a master station and slave stations and the simultaneous return of data in the direction of the master station, and this by means of a bus having only two conductors. The digital signals emitted by the master station are at the same time control signals feeding in power to the slave stations. The bits of these signals are of a shape such that they present dead zones during which these signals do not have any effect and during which one can interrupt the faithful transmission, while putting at high impedance one of the conductors of the bit, which allows a momentary alteration of the signal. Such an alteration is obtained by loading strongly the conductor put at high impedance, the presence or the absence of such an alteration constituting the data which has to be transmitted from one slave station to the master station.