The Network

The network

General
Increasing demands for further functionality in the car, both by statutory requirement and customers, have led to an increased complexity in the car.
This has in turn driven the development of more flexible electronic systems. The Controller area network (CAN) is a result of this research. The network allows a large number of different commands and messages to be transmitted and received on the same cable. Previously each command or message required a separate cable. By using the network functionality has increased without increasing the number of cables.
The number of commands and messages that can be handled by the network depends on the speed of the network and the length of the message / command. The Volvo network which is based on a Controller Area Network (CAN), can transmit over 500 different signals and approximately 100 messages (also known as frames). Each message can contain several signals, for example a message to the rear electronic module can contain all the signals for how the tail lamps should be lit.

Advantages of a network

Easier to add further functions and install accessories
Because the control modules in the network are already connected to each other and are easy to add more information to, all that is required is:
- to connect the sensors to the nearest control module
- to connect the controlled component to the nearest control module
- to download software to alter the configuration and programming of the network.
The length of the wiring and the number of components which are introduced with the car are less than previously.
An example of this is the addition of cruise control for the car.
Before the introduction of the network the installation of control modules, switches, vacuum pumps, vacuum servos, hoses and cable harnesses was necessary.
With the network only the installation of a switch and the downloading of software which alters the configuration of the car is required.

Easier to introduce logical functions
Logical functions can be explained as "if this occurs then the following corrective action must be carried out". For example, the system is programmed so that if a tail lamp is broken, a message is transmitted via the Controller area network (CAN) to the driver information module to warn the driver.
All that is required to introduce a logical function is to change the programming of the affected control module - the rear electronic module and driver information module in the example above.
Introduction of logic functions does not increase the number of components or cables.

Easy to adapt the system to customer and market requirements
The functions can be altered depending on the requirements of the customer and market. An example of this could be fog tail lamps. Certain markets use two fog tail lamps, others only use one on the driver's side. Previously it was required that different replacement parts were stored for different markets. Now the same replacement part can be used for all markets, by changing the programming depending on the market.

Similar basic systems can be used for a whole model program
Similar networks (hardware) can be used for a large number of different cars.
The only thing which differentiates the cars is:
- the components (control modules, sensors controlled components etc.) which are connected to the system
- Which components do what
- Which components/functions are standard /optional/accessories
- The configuration /programming of the system.