V50 L5-2.4L VIN 39 B5244S7 (2005)
Note! Even if two cars appear identical they may behave differently because of differing configurations; a parameter may have been modified
by the customer or workshop.
The Network
The network
General
Increasing demands for further functionality in the vehicle, both by statutory requirement and customers, have led to an increased complexity in the
vehicle.
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 which can be handled on the network depends on factors such as the network speed and the length of the
message or command. The Volvo network which is based on a control area network (CAN), can transmit over 500 different signals and approximately
100 messages. These messages are also known as frames. Each message can contain several signals.
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:
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To connect the sensors to the nearest control module
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To connect the controlled component to the nearest control module
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To download software to the control module to modify the configuration.
The length of the wiring and the number of components which are introduced with the car is 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 all that is required is the installation of a switch and the downloading of software which alters the configuration of the car.
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 control area network (CAN) to the driver information module (DIM) to warn the driver.
All that is required to introduce a logical function is to change the programming of the affected control module - the central electronic module (CEM)
and driver information module (DIM) 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 modified 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:
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Which components (control modules, sensors controlled components etc.) are connected to the system
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Which components do what
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Which components/functions are standard /optional/accessories
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Configuration/programming of the system.
Construction Of the Network
Construction of the network
General
The network is made up of a number of control modules (sometimes called nodes) which are connected to each other serially via two communication
cables. Each control module is supplied with power and grounded individually and receives messages / commands via the two communication cables. In
both networks (high and low speed sides) the control modules are connected to a number of different spurs. In the event of an open-circuit those control
modules beyond the open-circuit will not be able to communicate with other parts of the network. However, a failure in one of the spurs can lead to
