Rede de comunicação – Visão geral

418-00-5 Module Communications Network 418-00-5 DESCRIPTION AND OPERATION ‡ Connection of the sensors to the nearest control module ‡ Connection of the component which is to be actuated to the nearest control module ‡ Software-based adaptation of the module configuration This means that the overall length of cabling and the number of components in a vehicle are reduced compared to before. One example of this is the integration of the speed control system. Before the introduction of the network, control modules, switches, vacuum pumps, vacuum servos, hoses and wiring harnesses were needed for this system. Following introduction of the network, only one switch and the software for adaptation of the vehicle configuration are required. Easier to introduce logical functions The term "logical functions" is used to describe the concept whereby certain events trigger certain responses. For example, the system is programmed in such a way that if a tail lamp fails a message is sent via the Controller Area Network (CAN) to the electronic instrument cluster to warn the driver. A logical function can be introduced by merely reprogramming the affected control modules. In the above case this would be the body control module (BCM) and the electronic instrument cluster. The number of components and cables remains the same. Simple adaptation of systems to customer demands and market requirements Vehicle functions can be adapted to customer demands and market requirements, e.g. in the case of the rear fog lamps. In some countries two rear fog lamps are used, whereas in other countries only one fog lamp is used on the driver's side. In the past it was necessary to stock different spare parts for different markets. Now a single part is sufficient to cover all markets - it just needs to be programmed for the specific market. Use of similar basic systems for entire series Similar networks (hardware) can be used for a wide variety of different vehicles. The vehicles only differ in terms of: ‡ The individual components (modules, sensors, actuated components etc.) which are connected to the system. ‡ The task(s) of the components. ‡ The definition of the components as standard/optional/accessories. ‡ The configuration/programming of the system. The layout of the network. General The network is made up of a range of control modules (these are also referred to as nodes) which are connected to each other via two communication cables. Each module has its own voltage supply and ground connection and receives messages and control commands via both communication cables. In the event of a break in the circuit, the modules beyond the break cannot communicate with other parts of the network. Network areas with high and low data transfer rates The network consists of two parts. The area with the higher data transfer rate (HS CAN bus) transmits signals and messages between the body control module (BCM) and control modules which are mostly located in the engine compartment. The area with the lower data transfer rate (MS/MM CAN bus) transmits signals and messages between the body control module (BCM) and the control modules in the passenger compartment and in the luggage compartment. The body control module (BCM) represents the interface between the two areas and converts the data transfer rate up or down to allow the two areas of the network to communicate with each other. Data transfer rates The Controller Area Network (CAN) uses two data transfer rates. ‡ The HS/MM CAN bus (high data transfer rate) transfers data at a rate of 500 kBit/s. ‡ The MS CAN bus (low data transfer rate) transfers data at a rate of 125 kBit/s. 1 kBit/s 1024 Bit per second (1 Byte 8 Bit).