测量和控制用数字数据通信.工业控制系统用现场总线.第5部分:应用层服务定义

[中文适用范围]： IEC 61158 的这一部分是为促进自动化系统组件互连而制定的系列之一。它与三层现场总线参考模型定义的集合中的其他标准相关，该参考模型部分基于基本标准 [外文原描述]： This part of IEC 61158 is one of a series produced to facilitate the interconnection of automation system components. It is related to other standards in the set as defined by the three-layer fieldbus Reference Model, which is based in part on the Basic Reference Model for Open Systems Interconnection. Both Reference Models subdivide the area of standardization for interconnection into a series of layers of specification, each of manageable size. The Application Service is provided by the Application Protocol making use of the services available from the Data Link or other immediately lower layer. This part of the IEC 61158 series defines the Application Service characteristics that any immediately higher-level protocols may exploit. The contents of the corrigendum of July 2004 have been included in this copy.