Diagnosis on the FlexRay: Notes
FlexRay is a new bus system and communication system. FlexRay ensures reliable and very powerful data interchange in real time between the electrical and mechatronic components. FlexRay serves for networking innovative functions of today and of the future in the vehicle. FlexRay contains a powerful protocol for real-time-capable data transfer to different systems which are utilized in the vehicle. With a maximum data transfer rate of 10 MBit/s per channel, the FlexRay is very fast. The FlexRay is significantly faster than the data buses used to date in motor vehicles in the area of body as well as drive and chassis. FlexRay supports not only the higher bandwidth but also deterministic data interchange; its configuration is error-tolerant. This means that even after failure of individual components, reliable continued operation of the remaining communication systems is enabled. The central gateway module (ZGM) sets up the link between the various bus systems and the FlexRay.
Example F0x: FlexRay topology, maximum equipment
| Item | Explanation |
|---|---|
| SZL | Steering column switch cluster |
| EPS | electromechanical power steering |
| VTG | Transfer box |
| DME2 | Digital Engine Electronics 2 |
| DSC | Dynamic Stability Control |
| ICM | Integrated chassis management |
| DME/DDE | Digital Motor Electronics or Digital Diesel Electronics |
| EDCSVR | Damper satellite, front right |
| VDM | Vertical Dynamics Management |
| ZGM | Central gateway module |
| EDCSHR | Damper satellite, rear right |
| EME | Electrical machine electronics |
| HSR | Rear axle slip angle control |
| AL | Active front steering |
| SWW | Lane Change Warning |
| EDCSHL | Damper satellite, rear left |
| EDCSVL | Damper satellite, front left |
| PMA | Parking maneuvering assistant |
| R | Terminating resistor |
Example F2x: FlexRay topology, minimum equipment
| Item | Explanation |
|---|---|
| DSC | Dynamic Stability Control |
| DME/DDE | Digital Motor Electronics or Digital Diesel Electronics |
| EPS | electromechanical power steering |
| Front electronic module | Front Electronic Module |
| ICM | Integrated chassis management |
Depending on the vehicle equipment, the central gateway module (ZGM) is equipped with 2 star couplers each with 4 bus drivers. The bus drivers forward the data of the control units via the communication controller to the central gateway module (ZGM). Depending on the type of termination, the FlexRay control units are connected to these bus drivers in 2 different ways. Terminal resistors are used on both ends of the data lines on the FlexRay to prevent reflections. If only one control unit is connected to a bus driver (e.g. SZL on partial bus system 0, see the applicable wiring diagram), the connections at the bus driver and at the control unit are each fitted with a terminal resistor. If the connection to the control unit is not the physical end-node (e.g. DSC, ICM and DME on the 2nd partial bus system): The two components must be terminated at the ends of the respective paths with terminating resistors.