Applications Automotive Networking in the Vehicle – After we have discussed cross-system functions and requirements for the bus system, now is the time to discuss the application of automotive networking to a vehicle. We’ll see which parts of our cars use this kind of ‘complicated’ trim system. Thus, we will know or at least be aware of the condition of our vehicle for parts that have a networking system.
Applications Automotive Networking in the Vehicle
The overall vehicle system can be divided into four domains or functional areas from the point of view or electrics/electronics:
▶ Interior and
In the drivetrain and chassis domains, the emphasis is primarily on real-time applications. In the interior domain, the main focus is on multiplex aspects in networking. Mainly multimedia and infotainment applications are networked in the telematics domain.
The networking of these systems makes considerable demands of the performance capability of the communication system. Crankshaft-synchronous processes or processes within a fixed time frame with cycle times of a few milliseconds are typical. If the system response times are adequate for the task in hand, it is described as having real-time capability (e.g. rapid ignition timing advance in the Motronic after a request from the traction-control system for reducing torque and therefore preventing the wheel from spinning).
The drivetrain and chassis systems are assigned to class C. These require fast transfer rates in order to ensure the realtime behavior that is required for these applications. They also make considerable fault tolerance demands. These requirements are met by the event-driven CAN bus with a transfer rate of 500 kBaud (high-speed CAN).
▶ Engine-management system (Motronic or electronic diesel control, EDC)
▶ Transmission control
▶ Antilock brake systems, ABS
▶ Vehicle dynamics control (e.g. electronic stability program, ESP)
▶ Chassis control systems (e.g. active body control, ABC)
▶ Support systems (e.g. adaptive cruise control, ACC)
The multiplex application is suitable for controlling and regulating components in the body and comfort and convenience electronics area (class B), such as
▶ Access authorization with anti-theft warning device
▶ Seat and mirror adjustment
▶ Door module (power-window unit, door-mirror adjustment)
▶ Windshield wipers
▶ Headlamp adjustment
The transfer rate requirements are not as high for class B systems as they are for lass C systems. For this reason, low-speed CAN with a transfer rate of 125 kBit/s or single-wire CAN with 33 kBit/s. can be used.
If the transfer rate requirements drop to less than 20 kBit/s, the low-cost LIN is more frequently used. Applications are mainly in the mechatronics area; examples being the transfer of switch information or the activation of actuators.
Mobile communication applications combine components such as
▶ Car sound system
▶ CD changer
▶ Navigation system
▶ Driver-information systems
▶ Video system
▶ Voice input
▶ Internet, E-mail
▶ Back-up camera
The networking of these components makes it possible to have a centrally located display and control unit for several applications. Operating procedures can be standardized in this way, and status information can be summarized. Driver distraction is therefore minimized.
A distinction must be made between control data and audio/video data in multimedia networking. Transfer rates of up to 125 kBit/s are sufficient for control tasks (such as CD changer control), meaning that the low-speed CAN bus can be used, for example. The direct transmission of audio or video data requires extremely high transfer rates of more than 10 MBit/s. The MOST bus is used for this purpose, for example.