Digital Networks

The Alfa Romeo 4C electric/electronic system includes 5 interconnected control units on a CAN-C line, and a maximum of 6 control units on CAN-B.

Courtesy of CHRYSLER GROUP, LLC

The electronic control units sharing data on CAN-C are:

• BCM (Body computer node)
• ABS (Brake node - ABS - ESP)
• TCU (Robotised transmission node - TCT)
• ECM (Engine management node)
• SAS (Steering Angle Sensor)

The electronic control units sharing data on CAN-B are:

• IPC (Instrument panel node)
• NAB (Airbag node)
• TPM (Tire Pressure Module)
• NRR (Radio Receiver Node)
• PAM (Parking sensor node)
• VTA (Vehicle Theft Alarm - anti-theft module)

DESCRIPTION 

This vehicle is equipped with a CAN (Controller Area Network) system of electrical connections: it involves a software and hardware solution which is designed to efficiently manage the resources on the vehicle, allowing:

• The sharing of information between the various electronic units;
• The integration of several electronic units through one network;
• A high network information exchange speed;
• Advantages in economic terms because there is a considerable reduction in the wiring/connectors inside the vehicle;
• Higher standards in terms of quality and reliability.

The advantage of using a CAN system stems from the fact that communication takes place between numerous control units and consequently the number of signals to be managed is very high. For this reason the signals travel on a CAN type serial bus where one wire is high level (H) and the other low level (L); these signals on the CAN Bus are differential, i.e. the value assigned to the bit is represented by the difference between the CAN-H and CAN-L voltage levels.

The different electronic units which make up the system, known as network nodes, are connected to the CAN by means of communication interfaces known as transceivers; these connection interfaces, integrated in the electronic units, constitute the gate for sending/reading the information at the CAN or at the serial lines.

The exchange of information at CAN type serial lines is only possible using a transmission protocol which is the collection of rules that allow communication between two or more nodes by means of the exchange of information or data packages.

The main element of the network is the Body Computer. The Body Computer node is entrusted with "waking up the network" at key on (if there is a fault with the Body Computer this task is entrusted to the instrument panel). The Body Computer also carries out the network monitoring functions which make it possible to provide information on:

• The network activity status
• The functional failure status of the individual electronic units (nodes)
• A possible fault in the CAN

The various electronic units process the various signals coming from the corresponding sensors both for their own management and for other control units to which they are sent through the CAN. The specific structure adopted for this vehicle consists of two CAN communication networks that connect nodes belonging to two different areas:

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

Diagnosis of nodes connected to the network B-CAN and C-CAN is carried out via the specific diagnosis connector:

Power is distributed through the junction boxes and/or fuse boxes. These are connected to control elements (relays and static actuators) to ensure maximum electrical protection and minimum wiring complexity.

• The Body Computer M001 - connector A - receives a direct power supply from the battery through the line protected by maxi fuse F01 of the engine compartment control unit B001.
• The Body Computer M001 receives an ignition-controlled power supply (INT) at pin 11 of connector E: this signal is used, amongst other things, to "wake up the network". Pins 9, 10 of connector E of M001 provide the Body Computer with a reference ground.

The following nodes are connected to the Body Computer M001 via the C-CAN high speed network from pins 44 and 45 of connector B:

• Engine management control unit M010
• ESP/ESC control unit M051
• Twin clutch automatic transmission control unit M196

The nodes connected to the Body Computer M001 through the CAN-C high speed network from pins 24 and 26 of connector F are:

• Steering angle control unit (NAS) M092

The following nodes are connected to the M001 Body Computer via the low speed B-CAN:

• Instrument panel E050, from pins 18, 20 of connector F;
• Airbag control unit M060, from pins 16, 21 of connector F;
• Parking sensor control unit M084, from pins 34, 49 of connector C;
• Tire pressure control unit M047, from pins 37, 52 of connector C;
• Coupling for radio alarm setup D093, from pins 42, 43 of connector B;

The central diagnosis socket R010 is connected to the CAN-C at pins 25, 27.