【摘要】 IEC 61158－2是适合于恶劣工业环境使用的工业现场总线物理层标准。本文描述了该标准的物理层模型，模型中媒体相关子层MDS的主要功能及物理层协议数据单元PhPDU的组成。61158－2标准的导体媒质相关子层MDS使用了曼彻斯特码双相码，本文剖析了这种码型的特征。曼彻斯特码双相码所特有的一些特征，使该线路码非常适合于工业现场总线应用。更多还原

【Abstract】 IEC 61158－2 is the international standard of physical layer for use in industrial critical applications or industrial severe environment. The paper describes the general model of physical layer given in the standard, the main functions of the Medium Dependent Sublayer MDS and the sructure of PhPDU (Physical Layer Protocol Data Unit), and expounds the characteristics of the Manchester code adopted by the MDS of wire media. These peculiar characteristics of Manchester code make it clearly that this code type is very suitable to be used in industrial fieldbuses.更多还原