Optical-fiber CAN2.0B bus routing system based on star topology

Abstract

The invention discloses an optical-fiber CAN bus routing system based on star topology. The system includes a CAN bus. Multiple pieces of CAN communication equipment and Multiple pieces of CAN bus switches are disposed on the CAN bus. Each CAN switch is provided with at least one cascaded CAN interface and multiple common CAN interfaces. The CAN switches are connected through the cascaded CAN interfaces. The CAN communication equipment is connected to the normal CAN interfaces. The CAN communication equipment send data frames to the CAN bus switches, and the CAN bus switches identify class-A routing request frames, class-B routing request frames and CAN information frames according to the data frames; and the CAN switches establish and maintain routing tables through interaction of the class-A and class-B routing request frames, and a routing function of the CAN information frames is realized through a manner of routing table finding of the CAN switches. The method of the invention issimple, calculation speed is high, hardware costs are low, flexibility is good, and routing under the star topology can be realized in optical-fiber CAN communication, any topology connection among the CAN switches is supported, and requirements of complex networking are met.

Description

technical field [0001] The invention relates to a CAN bus routing system, in particular to an optical fiber CAN2.0B bus routing system based on a star topology. Background technique [0002] CAN bus technology was originally used in the monitoring system of automobiles in 1986 by the German BOSCH company. It is based on a non-destructive arbitration mechanism. When a packet conflict occurs, the node with a lower priority will actively hand over the control of the bus to a node with a higher priority, thereby greatly reducing the bus conflict arbitration time. The CAN2.0B protocol standard only defines the physical layer and data link layer specifications. Users need to customize the application layer protocol according to the project needs. Currently, the commonly used application layer protocols include CANopen, DeviceNET, TTCAN, etc. [0003] At present, the twisted-pair cable CAN transceiver following the ISO11898 standard has gradually become the mainstream, and the vas...

AI Technical Summary

Problems solved by technology

[0004] The optical fiber CAN bus mostly adopts ring or star topology. The star bus topology generally uses the CAN bus hub to perform photoelectric logic conversion at the physical layer to complete the connection, but this method is difficult to realize the interconnection between multiple CAN bus hubs.

The reason is that the CAN standard itself does not have the routing capability between multiple subnets, and can only rely on the form of electrical connection to complete bus arbitration

Images