Multiplex Communication System

System Diagram:

SYSTEM DESCRIPTION

Basic of MPX (Multiplex Communication)

1. General




The SEQUOIA multiplex communication system uses serial communication, which converts multiple pieces of information into serial communication data. As a result, they can be transmitted through a single communication wire.




Serial communication data consists of bits and frames. A bit is the basic unit that represents the amount of information. A bit is represented by a binary value "0" or "1". A frame is a body of data that is transmitted together. A frame contains a "header" that indicates the beginning of the data and an "end message" that indicates the end of the data.

2. Network Style




Based on serial communication, various ECUs are connected on a network to exchange various pieces of information. Such a system is called a multiplex communication system.

The BEAN (Body Electronics Area Network) uses the ring and bus styles of networks to connect ECUs. This connection style is called a daisy chain. In the daisy chain, communication can be maintained even if there is an area that has an open circuit.

3. DIAGNOSIS SYSTEM




a. If a DTC for an ECU communication stop is indicated, a connector may be disconnected or there may be open circuits on 2 or more communication buses. When there is an open circuit on only 1 communication bus, no DTC will be detected.




b. If 2 communication buses are open at the position shown in the illustration, DTCs for the ECU communication stop between these 2 buses are indicated.