Brief component description: Gateway

The central gateway module (ZGM), which is integrated in the Front Electronic Module (FEM) carries out vehicle-internal distribution of the messages to the various data buses. The messages are forwarded to the headunit via K-CAN2. The headunit then distributes them on the Media Oriented System Transport.

Within the system network, the control units involved communicate via the following bus systems:

• The Media Oriented System Transport (MOST) uses optical fibres for data transfer. Data transfer is only possible in one direction. Data exchange is performed via the central gateway module (ZGM).
• FlexRay is employed as the bus system for networking of dynamic handling control systems and engine control. The central gateway module (ZGM), which is integrated in the new Front Electronic Module (FEM), contains a so-called star coupler with 4 bus drivers. The bus drivers pass the data on to the central gateway module (ZGM). The FlexRay control units are connected to these bus drivers. To avoid reflection on the lines, terminating resistors are fitted on both ends. FlexRay has a very high data transfer rate (10 MBit/s) and allows data exchange between the control units at a stipulated time.
• The K-CAN (body CAN) is responsible for control unit communication at low data transfer rates (100 kBit/s). The K-CAN is also linked to the other bus systems via the central gateway module (ZGM).
• The K-CAN2 (body CAN 2) is responsible for control unit communication at high data transfer rates (500 kBit/s). The K-CAN2 is also linked with the other bus systems via the central gateway module (ZGM).
• The PT-CAN (powertrain CAN) connects the engine control with the transmission control unit, and also the safety system with the assist systems.
• The PT-CAN2 (powertrain CAN 2) creates a redundancy to the Powertrain Controller Area Network (PT-CAN) in the area of the engine control and transmission control unit. The PT-CAN2 has a data transfer rate of 500 kBit/s and is equipped with an additional wake-up line.
• The LIN (local interconnect network) is mainly used in a master and slave combination. The local interconnect network bus ensures fast and reliable communication between the control units within a functional group.
• The Ethernet is a vendor-neutral, cable-based technology for the connection of networks. As a result of the Ethernet's very high data transfer rate (100 MBit/s), the interface via the Media Oriented System Transport bus of the central gateway module (ZGM) in the Front Electronic Module (FEM) was no longer required. Due to the high data volumes, programming of the MOST network is carried out via the Ethernet and the headunit. The headunit performs distribution on the MOST. Vehicle diagnosis messages are transmitted to the headunit via K-CAN2.

Manipulation or modification of the encoding data is no longer easily possible.