3023171 - E1050 CAN CONNECTION LINES - Description

Description

This vehicle features a CAN network (Controller Area Network) system of electrical connections: it involves a software and hardware solution which is designed to manage the resources on the vehicle in an increasingly efficient way, allowing:

  • data to be shared between the various electronic units;
  • the integrattion of several electronic units in one network;
  • a high data exchange speed in the network;
  • ensure cost-effective solutions, since the number of wiring harnesses and connectors are considerably reduced in the vehicle;
  • a higher standard in terms of quality and reliability.
The advantage of using a CAN system stems from the fact that the communication involves numerous control units and consequently the number of signals managed is very high.For this reason the signals 'travel' on CAN type (double) serial Bus, where one wire is associated with the high level (H) and the other the low level (L); These CAN Bus signals are differential, i.e. the value assigned to each bit is represented by the different voltge of CAN-H and CAN-L.The various electronic units which make up the system, known as network 'Nodes', are connected to the CAN by means of communication interfaces known as transreceivers; These connection interfaces, integrated in the actual electronic units, form the gates for sending/reading information at the CAN or at the serial lines.A 'transmission protocol', i.e. the set of rules allowing the communication between two or more ECUs (called Nodes) by means of data or data package exchanges, is required for CAN serial line data circulation.The main element in the network is the Body Computer. The Body Computer node 'wakes the system up' when the ignition key is turned to the ON position (if there is a Body Computer failure, the task of waking the system up is entrusted to other nodes  Characteristic of working principle 5505  ELECTRICAL CIRCUIT FOR INSTRUMENTS/INDICATORS .

The Body Computer also carries out the functions of controlling the network, which makes it possible to supply information on:

  • the network activity status;
  • the functional failure status of the individual electronic units (nodes);
  • the possible CAN failure.
The various electronic units process the signals coming from their sensors either for their own management or for other control unit, sent via the CAN network.

The specific structure adopted on this vehicle consists of two CANs which connect nodes belonging to two different areas:

  • C-CAN for 'dynamic control' of the vehicle (high speed): bus CAN-H and CAN-L;
  • B-CAN for the management of 'bodywork functions' (low speed): bus CAN-A and CAN-B; te two CAN communication networks are connected to one another by means of a gateway for transferring joint information, located in the Body Computer Node.

The following nodes are connected to the Body Computer via the C-CAN:

  • engine management control unit;
  • ABS control unit;
  • steering sensor unit for VDC.

The following nodes are connected to the Body Computer via the B-CAN:

  • climate control system control unit;
  • instrument panel;
  • radio or radio phone-navigator
  • control unit in driver's door
  • electric rear windows unit
The diagnosis of the nodes connected to the bodywork network is achieved via the CAN, whilst the vehicle dynamic control network is diagnosed using the special K lines  See E8010  DIAGNOSTIC MULTIPLE CONNECTOR . The system also uses additionional 'traditional' serial lines for the various connections; for example, in the connection between the Body Computer and the alarm / volumetric sensors  See E7015  ALARM . The distribution of power takes place via the junction units and/or fuse boxes, connected to the control elements (relays and static actuators) in order to ensure the maximum level of electrical protection and the minimum degree of wiring complexity  See E1010  SUPPLY .