Background | Overview | Features | In-car Communication Protocol | Target applications | Data transfer method | Difference with CAN | Internal configuration of a node | Electronic signals | Bus Guardian | Topology | Segment configuration | Protocol | Status transition | Error control |
FlexRay
Difference with CAN
The following table shows the comparison of major specifications of FlexRay and CAN.
Comparison between FlexRay and CAN
| No. | Compared item | CAN | FlexRay |
|---|---|---|---|
| 1 | Baud rate | 1Mbps | 10Mbps |
| 2 | Number of channels per a node | 1ch | 2ch/1ch (option(1)) |
| 3 | Network topology | Bus-type | Bus-type, Star-type, or Coexisting |
| 4 | Connected nodes (max) | Depending on the delay time of the bus | Bus-type: 22 nodes Star-type: 22 nodes or 64 nodes during active Coexisting: 64 nodes |
| 5 | Physical layer | Metal | Metal/PoF |
| 6 | Communication | Event trigger | Time trigger + event trigger |
| 7 | ID | 11bits/29bits | 11bits |
| 8 | DLC | 8bytes | 254bytes |
| 9 | Frame | Data Frame, Remote Frame, Error Frame, Over Rode Frame |
Data Frame |
| 10 | Bus line lock | Possibly be dominant lock(2) | Babbling Idiot(3) (supported by BG(4)) |
| 11 | Error status transition | Error Active, Error Passive, Bus off (recoverable by software) |
Normal Active, Normal Passive, Halt (recoverable by a reset or software command) |
| 12 | Error counter | Fixed status transition counter value | Arbitrary status transition counter value |
| 13 | Type of errors | Bit Error, Staffing Error, CRC Error, Framing Error, ACK Error |
All errors except a clock synchronization |
| 14 | Oscillator | Ceramic oscillator or crystal oscillator | Crystal oscillator (BG(4) is separated from the CC(5) clock) |
| 15 | NW management | By software | By hardware (by BD(6) or BG) |
| 16 | Network synchronization | Synchronized only by sync_seg | Rate correction and offset correction are available. |
| 17 | Bus length | 40m at 1Mbps | 22m (between nodes, between Active-Star and node, and between Active-Star and Active-Star.) |
Explanations
- 1 Option:
- The option means it can be switched by the setting value.
- 2 Dominant lock:
- Dominant lock means that Bus is stuck to "0".
- 3 Babbling Idiot:
- Babbling Idiot means that incorrect transfer causing damage occurs.
- 4 BG:
- BG stands for bus guardian.
- 5 CC:
- CC stands for communication controller.
- 6 BD:
- BD stands for bus driver.
- Note -
Some parts of this site show only the outlines of the actual FlexRay standards to make them easily understood.
