Study And Design Of Structure And Communication Protocol For A No-master And Multi-node Fiber-optic Field Bus

To solve the communication problems of vehicle test,UAV test and hazardous environment test,this paper studies and designs a no-master and multi-node fiber-optic bus to realize the real-time and high-speed communication between multiple equipment nodes.Because of the high performance requirements in transmission distance,transmission capacity,real-time and reliability,and the requirement of multiple equipment nodes for vehicle,UAV and other systems,and the high performance on,the traditional bus technology has been difficult to meet the needs of the above.Therefore,this paper studies and designs a fiber-optic field bus with high communication speed,long communication distance and high real-time performance,combines time sharing and free competition,high-speed optical transceiver module and star topology,solves the problem of multi-node and long-distance high-reliability real-time communication by using bus protocol.In this paper,the new fiber-optic field bus is studied as follows:(1)The design of system structure.To build a new optical fiber field bus,we need to consider which topology can achieve high-speed and reliable communication between multiple field equipment.This paper analyses and optimizes the ring topology and the star topology respectively,decides to use the star topology which has simpler structure and better power consistency to complete the construction of the bus interface circuit and the protocol model.(2)The design and implementation of the hardware interface module.The hardware interface circuit includes the optical transceiver module which is connected to the bus part and the digital control module which is connected to the field equipment.According to the parameter requirements of the system,the following works are done,including the selection of various chips,the design of schematic and PCB.Then,the hardware platform of the optical fiber field bus is made.(3)Implementation of fiber-optic fieldbus protocol.According to the requirement of real-time and flexible performances of fiber-optic field bus,a bus protocol based on TDMA is designed.The protocol divides the bus communication process into many basic cycles.Each basic cycle contains fixed time windows and free time windows.Meanwhile,the high real-time property is reflected by fixed time windows,and the high flexibility is reflected by the free time window.Finally,according to the hardware platform of the fiber-optic field bus,the bus protocol is tested,and the bus communication process can be strictly carried out according to the bus protocol.