标准摘要
[中文适用范围]： 数据链路层在自动化环境中的设备之间提供基本的时间关键消息通信。该协议向所有参与的数据链路实体a)以同步启动循环方式，以及b)以循环或非循环异步方式提供通信机会，如每个数据链路实体在每个周期所请求的。因此，该协议的特点是异步提供循环和非循环访问，但每个周期同步重新启动。 [外文原描述]： IEC 61158-4-12:2010 specifies procedures for the transfer of data and control information from one data-link user entity to one or more user entity; the structure of the DLPDUs used for the transfer of data and control information by the protocol of this standard, and their representation as physical interface data units. This second edition cancels and replaces the first edition published in 2007 and constitutes a technical revision. The main changes with respect to the previous edition are: bug fixes and editorial improvements. This bilingual version (2012-05) corresponds to the monolingual English version published in 2010-08.
英文名称Industrial communication networks - Fieldbus specifications - Part 4-12: Data-link layer protocol specification - Type 12 elements