Network

Design and Function

General

Increasing demands on functionality have made the electrical system in vehicles increasingly complex. By using a network with serial communications between the different control modules several functions can be controlled and monitored using fewer cables.

Example of networks using serial communications are CAN and LIN.

LIN is an acronym for Local Interconnect Network and has been jointly developed as a common standard by a number of different automotive manufacturers.

The concept involves the exchange of information, via serial communications with a single wire, between control modules where the same performance as provided by a CAN network is not needed.

LIN is usually used as a communications line between control modules on the CAN network and minor nodes, such as regulators and advanced sensors.

The number of control modules that communicate via LIN is dependent on the vehicle model and the level of equipment.

The difference between CAN and LIN is that the CAN network is routed throughout the entire vehicle. Whereas LIN is usually used in smaller separate networks where the transfer speed and performance is not so highly prioritised. See the wiring diagram for the vehicle model in question for topographical differences between LIN and CAN.

Advantages of a network

Instead of using a single wire for each function, serial communications over a network make it possible for hundreds of signals and functions to be activated, controlled or read via the same wire.

Using a network it is even easier to adapt the system to customers and markets.

In relation to the number of functions and connected components the length of the wiring is short and the electrical system is more service friendly when based on a network instead of direct connection.

General

The increasing requirements of extended functionality in vehicles has underpinned the development of systems with better performance and more functions. The MOST network is a result of this development.

The MOST network is a fiber optic network which allows a high number of different commands and messages to be sent and received on the same cable and in the same direction.

By using a fiber optic network, functionality is extended without increasing the amount of wiring.

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 MOST network which is used in Volvo cars has the capacity to transmit over 300 message types and approximately 1000 messages per second. The transfer rate on the MOST network is approximately 25 Mbit/s.

Advantages of an optical network

• electrical short-circuits are not possible on the MOST network. This reduces the risk of damage to control modules connected to the network
• As an optical network, the MOST network does not have problems with EMC (Electro Magnetic Compatibility)
• the wiring is not sensitive to electrical cross-induction from other wiring
• The transfer speed of the MOST network is much higher than the CAN
• it is easy to add further functions and to install accessories, known as plug and play units.

The control modules in the network are connected to each other and are constructed so that more functionality can be easily added. All that is required to increase functionality is:

• to connect the sensors to the nearest control module
• to connect the controlled component to the nearest control module
• to download software to change the configuration and programming of the network.

Applies to: 2014–2016

General

The MOST network is a fiber optic network which allows a high number of different commands and messages to be sent and received on the same cable and in the same direction.

By using a fiber optic network, functionality is extended without increasing the amount of wiring.

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 MOST network which is used in Volvo cars has the capacity to transmit over 300 message types and approximately 1000 messages per second. The transfer rate on the MOST network is approximately 25 Mbit/s.

Advantages of an optical network

• electrical short-circuits are not possible on the MOST network. This reduces the risk of damage to control modules connected to the network
• As an optical network, the MOST network does not have problems with EMC (Electro Magnetic Compatibility)
• the wiring is not sensitive to electrical cross-induction from other wiring
• The transfer speed of the MOST network is much higher than the CAN
• it is easy to add further functions and to install accessories, known as plug and play units.

The control modules in the network are connected to each other and are constructed so that more functionality can be easily added. All that is required to increase functionality is:

• to connect the sensors to the nearest control module
• to connect the controlled component to the nearest control module
• to download software to change the configuration and programming of the network.