FlexRay Fundamentals. With its data rate of up to 10 MBit/s FlexRay is targeting applications such as X-by-wire and the powertrain, which require a deterministic . Nov 9, FlexRay Protocol HardWare. 6. 11/9/ Demo: There are 13 nodes in our network. 1 is TMSLS, and others are TMSLS Sep 27, FlexRay: Communication in distributed systems within automotive context. • developed by the FlexRay consortium (BMW, DaimlerChrysler.

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FlexRay Automotive Communication Bus Overview

Ethernet may replace FlexRay for bandwidth intensive, non-safety critical applications. Header, Payload, and Trailer. Archived from the original PDF on 16 February Static Segment Figure 3: FlexRay has the unique ability to sync up nodes on a network without an external synchronization clock signal.

Back to Top 7. FlexRay is commonly used in a simple multi-drop bus topology that features a single network cable run that connects multiple ECUs together. This provides many advantages for systems that depend on up-to-date data between nodes. Star Network The FlexRay standard supports “Star” configurations which consist of flexra links that connect to a central active node. Back to Top 5. If it doesn’t broadcast, it loses its spot in the dynamic frame and the next minislot occurs.

If two nodes were to write at the same bssics, you end up with contention on the bus and data becomes corrupt. The startup frames are analogous to a start trigger, which tells all the nodes on the network to start. Each bit to be sent is held on f,exray bus for 8 sample clock cycles. All the communication is sent in the form of frames.


While flexible and easy to expand, this technique does not allow for very high data rates and cannot guarantee timely dlexray of data. The network idle time is of a pre-defined, known length by ECUs. Articles needing additional references from January All articles needing additional references All articles with specifically marked weasel-worded phrases Articles with specifically marked weasel-worded phrases from April If nothing is being communicated, the bus is held in state 1 high voltageso every receiver knows that the communication started when the voltage drops to 0.

Most first-generation FlexRay networks basicss utilize one channel to keep wiring costs down, but as applications increase in complexity and safety requirements, future networks will use both channels.

FlexRay – Wikipedia

Adoption of a new networking standard in complex embedded designs like automobiles takes time. The Payload Length contains the number of words which are transferred in the frame.

Illustration of a static slot with ECU 2 missing. The length of the FlexRay payload or data frame is up to words byteswhich is over 30 times greater compared to CAN.

Payload of a FlexRay Frame. Startup Frames and Sync Frames. The FlexRay communications bus is a deterministic, fault-tolerant and high-speed bus system developed in conjunction with automobile manufacturers and leading suppliers.

FlexRay Automotive Communication Bus Overview – National Instruments

For security-critical applications, the devices connected to the bus may use both channels for transferring data. Once a minislot occurs, an ECU has a brief opportunity to broadcast its frame. If the dynamic frame window ends, then the lower-priority minislots must wait until the next cycle for another opportunity to broadcast. Trailer of a FlexRay Frame. Figure 5 shows ECU 1 broadcasting in its minislot since the first 7 minislots chose not to broadcast.


For automobiles to continue to improve safety, increase performance, reduce environmental impact, and enhance comfort, the speed, quantity and reliability of data communicated between a car’s electronic control units ECU must increase.

Here’s an example of a particularly bad case – error during synchronization, a lost cycle due to clock drift and error in transmission. Too much or too little termination can break a FlexRay network. The dynamic segment operates flexxray like CANwith nodes taking control of the bus as available, allowing event-triggered behavior. Note that 8-cycle per bit has nothing to do with bytes.

Small transmission errors during the receiving may affect only the boundary bits. After years of partnership with OEMs, tool suppliers, and end users, the FlexRay standard has emerged as the in-vehicle communications bus to meet these new challenges in the next generation of vehicles.

FlexRay accomplishes this hybrid of core static frames and dynamic frames with a pre-set communication cycle that provides a pre-defined space for static bzsics dynamic data. Advanced control and safety systems–combining multiple sensors, actuators and electronic control units–are beginning to require synchronization and performance past what the existing standard, Controller Area Network CANcan provide.

Technical and de facto standards for wired computer buses. The bus operates on a time cycle, divided into two parts: Actual FlexRay networks may contain up to several dozen static slots. This article needs additional citations for verification.