| In ship navigation system,the emergence of the field bus to realize the digital communication and message passing between the intelligent navigation equipment,for the development of navigation system provides a wider field.However,the phases of technology development,the history of the differences in the field of application and related problems caused the ship navigation system tend to have a variety of field bus,and because of the communication protocol between these different fieldbus difference cannot be directly connected,usually need to interact through protocol gateway to implementation of news.Agreement on the market at present,however,the gateway can only solve the communication between the two different bus and belongs to the one-to-one protocol conversion device,however,exist in a system of three or more bus protocol,the protocol gateway is very difficult to achieve the entire network interconnection.In order to solve such problems,we need to conduct the thorough research to the multi-protocol conversion technology and implementation method.This topic from set out actually,in view of the navigation system used in four bus(1553B bus and CAN bus and Ethernet,RS-232),design and implements a multi-protocol conversion equipment based on ARM-Linux,completed the four real-time transfer protocol multiple directions.Under the requirements of ship information network,this paper studies the protocol conversion technology in the development of both at home and abroad,analyzed the 1553 B bus and CAN bus and Ethernet and RS-232 bus structure characteristics and protocol messages of frame structure,by parallel analysis and comparing the characteristics of the four bus,established a multi-protocol conversion model based on Petri net,in the model analyzes the multi-protocol conversion principle and has proved its feasibility.On this basis,this paper puts forward a kind of transparent multi-protocol conversion scheme,in the scenario,in order to achieve three or more multi-protocol conversion,so the protocol conversion need in the application layer to complete the main process,multiple protocols are implemented by the upper application of real-time conversion,and designed a special protocol frame to realize automatic routing functions.This paper adopted ARM9 processor as the control core,used embedded Linux as an operating system,designed and implemented the multi-protocol conversion device of hardware and software system.In the process of the implementation of the hardware system,this paper mainly designed has realized bus interface hardware circuit based on BUS-61560 protocol chip;In the process of the implementation of software system,this paper completed the driver of bus interface design and development,and transplanted the embedded Linux operating system in view of the iTEK9261 S development board,and At the same time,based on its priority preemption,divided the function of multi-protocol conversion task,and designed the communication process scheduling,in order to meet the requirements of the system.Finally,this paper developed a simulator of ship navigation system based on VC,constructed laboratory test system.In 1553 B bus and CAN bus and Ethernet and RS-232 network,completed the multi-protocol conversion equipment function and performance test,the test includes protocol conversion device in communication and protocol conversion,and protocol conversion equipment of packet loss rate and packet delay.Test results show that the protocol conversion device can realize four bus protocol conversion,and guaranteed the real-time and reliability. |
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