Volvo S80: The smart electrical system of the future. Today.

An increasing number of advanced functions, more and more computers and electric motors have meant that the conventional electrical system can be developed no further. For the Volvo S80, Volvo has chosen a new solution, a new approach and a smart system for the future: Multiplex.

Just like modern society, modern cars demand ever more in terms of communications. This is why Volvo chose a completely new concept and a new method for communicating signals in the car in a "language" that can be understood by all the components in the system.

The system is called Multiplex and is based on a communication network with central control units and more than twenty modules which handle the majority of electrical functions in the car. These modules function as computers and control the various functions as commanded. The commands are transmitted digitally using a system called multiplex - thereby giving the system its name.

Two main cables
The new electrical system is based on only two cables around the car. These are known as data busses. A single cable has enough capacity to carry all the signals in the cable at the same time. The other cable is the power cable which carries the electricity required to manoeuvre the different functions.

The information, or commands, travel as digital signals through the cable and each module in the network recognises its own command signals.

When the driver presses a button to adjust the right outer rear-view mirror, only the module in the right front door recognises the signal and receives it. The module then transmits an order to the electric motor to move the mirror.

The large capacity of the Multiplex system means that signals can constantly activate the different modules, with no limitation.

The signals also travel at two different speeds, depending on which function is involved. The engine and transmission management systems use a high-speed buss, while others have a somewhat slower one.

Many advantages
The Multiplex system offers many advantages:

· Fewer cables and connections are needed in the car, which saves both weight and space, consequently reducing fuel consumption and improving reliability.
· Complete communication between all the components and all the software in the car facilitates service and trouble-shooting.
· Fewer basic variants are required since the car is programmed at the factory on the basis of the customer's order according to specifications and equipment.
· Simpler and easier retrofit of electrical functions and upgrading of the car's software system.

The Multiplex system also offers self-diagnosis for all functions, including the engine management system, which makes the OBD unit (OnBoard Diagnostics) even more important than before. This makes it easier to find faults and carry out service. All the information on a lost function or other faults is transmitted directly to the driver via the indicator lamps and in plain language in a display window in the instrument panel.

Multiplex technology opens up new possibilities in the car's electrical system. It breaks new ground with its design and function and offers substantial advantages over a conventional system.

In the Volvo S80, the electrical system of the future is already reality.