Electrical system for a motor vehicle

Claim 1

An electrical system for the distribution of electrical power to user devices installed on board a motor vehicle equipped with a dashboard, said electrical system assembly comprising a plurality of electronic microprocessor control units, each of said control units being connected with a source of electrical power and being connected with one another by a multiplex communication bus, one of said control units being a main control unit for controlling the operative functions of the user devices, signaling means being connected to said main control unit for sending signals to said main control unit to indicate user's request for actuation of particular user devices, said control units further including first and second secondary control units, said first and second secondary control units being disposed between said main control unit and selected user devices, said first and second secondary units receiving signals from said main control unit and in turn actuate respective user devices and feed signals to said main control unit indicative of operating conditions of the respective user devices, said multiplex communication bus being a serial interconnection line, said secondary units containing power stages for the actuation of said respective user devices, and being connected to a source of electrical power suitable for said power stages, said serial interconnection line being formed by two leads, said two leads of said communication bus being connected to said main unit and said first and second secondary control units through transmission interfaces and reception interfaces wherein the transmission interface sends to one of said leads a first signal to be transmitted and sends to the other of said leads a second signal which complements said first signal, the reception interface being provided to compare the first and second signals with one another and if the difference is within a pre-established value, the first signal passes into the control unit to which it is addressed.