基于仪表总线的嵌入式通信接口的设计研究

【作者】 谭文忠；

【导师】 王晓兰；

【作者基本信息】 兰州理工大学 ， 电力电子与电力传动， 2004， 硕士

【摘要】 仪表总线，作为欧洲标准的“三表”专用总线，近年来已引起国内仪表界的广泛关注。本论文主要论述了仪表总线的通信机理及其嵌入式主从通信接口的设计。论文首先研究了METER-BUS(简称M-BUS)的通信协议。它与现场总线一样也是参照了ISO-OSI七层参考模型；不同的是：M-BUS在7个OSI层的上面又定义了一个管理层以直接修改地址、波特率等参数。同时，为了将不同类型的智能计量仪表采集的信号集成到M-Bus系统，本文从如下两方面作了探讨： (1) 各仪表设计应遵循的特定要求； (2) 开发一种专用的总线接口将户用计量仪表(包括水表、燃气表、热量表等)与M-Bus系统链接，并探讨了总线接口的物理性能、数据链路、数据标识及数据安全性和数据表达格式的要求。嵌入式通信接口的设计是仪表总线的关键部分，也是研究仪表总线的难点部分。它包括主机接口的设计和从机接口的设计。本文所设计的主机接口的功能是，将来自PC机上的RS232电平转换成M-Bus电平，以便于给M-Bus终端仪表远程供电及搜索、读取、管理为数多达250个的终端仪表；所设计的从机接口的功能是，按要求发送、接收数据，并将终端仪表的数字信号转化成M-BUS电平信号。从结构上来说，本文所设计的主机接口包括：电压供应模块、发送器、接收器、中继器及过载报警模块；所设计的从机接口包括：由MSP430微处理器构成的从机控制器模块及TSS721A构成的总线电源驱动模块。在信号调制方式上，实现了主机接口向从机接口发送数据的电压调制，以及从机接口向主机接口发送数据的电流调制，而且数据传输线和电源线合二为一，终端仪表通过从机接口以总线、电池、总线／电池三种方式获取电源。在软件设计中，主要设计了主机接口根据通配符搜索从机的程序及从机接口按要求发送、接收数据的程序。论文给出了通信系统的结构图，接口的硬件原理图及主要软件的流程图。论文在远传预付费系统的三表集成和主从机接口的设计方面具有一定的创新。更多还原

【Abstract】 M-bus , as a Europe standard of water meter ,gas meter,and electricity meter, has attracted wide attentions in instrument field. The mechanism of m-bus communication and its embedded master and slave interface for communication are researched.As a toll-gate between bus and terminal unit, bus interface should meet all those requirements of M-bus such as :communication protocol and feature of data transmission. Therefore, it is necessary to research the communication protocol for M-bus before commencing bus interface. As the same with the Fieldbus, the protocol is based on ISO-OSI (International Standard Organization-Open System Interconnection) , but it is not different from Fieldbus in many aspects, above which are designed a management layer to control the parameters of address , baud rate and so on.At the other hand, in order to integrate the signals from different terminal instruments into M-Bus system , for instance AMR (Automatic Meter Reading system) ,there are two ways to fellow :a) .Designing terminal instruments according to the same prescriptive standards;b). Developing a special bus interface so as to link terminal instruments and M-Bus system.For the purpose of the paper, great efforts are made to research the process of bus interface dealing with data ,such as the basic principle of data transmission , interface forms and the requirements including physics features, data link, data ID (identification),data security and data format. All those can get the result that they benefit to help data link between slave station and master station unseallingly.The design of the embedded interface for communication is one of the key parts and difficulties in the process of researching M-bus. It includes master interface and slave interface. The function of master interface is to convert the RS485 voltage into M-Bus voltage so as to supply terminal instruments and to search, read, manage up to 250 terminal instruments. Meanwhile , the function of slave interface is to convert the data from terminal units into M-bus pulse signal according configuration of pulse increment and unit of different terminal instruments. For structure, master interface includes power supply module, transmitter module, receiver module, overload warning module, and repeater module; slave interface includes MSP430 micprocessor module and Microcontroller --TSS721A transceiver module. For signal modulation, it is modulated by voltage from master to slave and by current from slave to master, what is most important is that data transmitter and power supply share one signal line .In the process of soft designing, the keys are to search slaves according Wildcards and exchange character between interface and terminal instrument. The related flow diagram and principle diagram about soft and hard designing are given in the paper.There are some innovations in the fellowing aspects:a) Integrating water meter ,gas meter,and electricity meter into one system;b) Soft and hard designing.更多还原