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。该协议以循环同步方式顺序地向所有参与的数据链路实体提供通信机会。前台计划访问可用于时间关键的活动，而后台非计划访问则可用于不太关键的活动。可以以高达 1 ms 的循环间隔和 25 km 的设备间隔提供确定性和同步传输。在正常操作继续的同时，通过重新配置本地链路的参数，可以动态地在线调整该性能。通过类似的方式，可以在正常操作期间添加或删除DL连接和新设备。该协议提供了在扩展链路上保持时钟同步的方法，其精度优于 10 μs。该协议通过将多个 DLSDU 和关联的 DLPCI 连接成单个 DLPDU 来优化每个访问机会，从而提高主动获取多个数据流的数据链路实体的数据传输效率。最大系统规模是无限数量的 99 个节点的链路，每个节点有 255 个 DLSAP 地址。每个链路最多有 224 个相关对等点和发布者 DLCEP。 [外文原描述]： IEC 61158-4-2:2010 provides communication opportunities to all participating data-link entities, sequentially and in a cyclic synchronous manner. Foreground scheduled access is available for time-critical activities together with background unscheduled access for less critical activities. It provides means to maintain clock synchronization across an extended link with a precision better than 10 ms. This protocol optimizes each access opportunity by concatenating multiple DLSDUs and associated DLPCI into a single DLPDU, thereby improving data transfer efficiency for data-link entities that actively source multiple streams of data. 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: - update of normative and bibliographic references; - update of abbreviations; - updates of the Ethernet Link object; - new DLR and QoS objects; - new DLR protocol. This bilingual version (2012-07) corresponds to the monolingual English version, published in 2010-08.
英文名称Industrial communication networks - Fieldbus specifications - Part 4-2: Application layer protocol specification - Type 2 elements