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型消息通信。 该协议为预先选择的用户提供通信机会？主人数据链实体的子集，以循环异步的方式，顺序连接到这些数据链实体中的每一个。其他数据链路实体仅在这些主数据链路实体允许和授权的情况下进行通信。 对于给定的主机，其与其他数据链路实体的通信可以是循环的，也可以是非循环的，具有优先访问权，或者两者的组合。 该协议提供了一种以公平方式共享可用通信资源的方法。有时间同步和等时操作的规定。交叉引用:IEC 61158-3-3:2014IEC 61158-2:2014ISO/IEC 7498？3ISO/IEC 2022ISO/IEC 7498-3ISO/IEC 7498-1ISO/IEC 7498？1IEC 61131-3ISO/IEC 10731ISO/IEC 646ISO 1177ISO/IEC 8802（所有部分）IEC 61158-1IEC 60870- 5-1IEC 61158-6-3IEC 61158-5-3IEC 61784-1ISO/IEC 3309IEC 61784-2替换BS EN 61158-4-3:2014，其保持当前状态。购买本文件时可获得的所有现行修订均包含在购买本文件中。

The data-link layer provides basic time-critical messaging communications between devices in an automation environment. This protocol provides communication opportunities to a pre-selected?master?subset of datalink entities in a cyclic asynchronous manner, sequentially to each of those data-link entities. Other data-link entities communicate only as permitted and delegated by those master data-link entities. For a given master, its communications with other data-link entities can be cyclic, or acyclic with prioritized access, or a combination of the two. This protocol provides a means of sharing the available communication resources in a fair manner. There are provisions for time synchronization and for isochronous operation.Cross References:IEC 61158-3-3:2014IEC 61158-2:2014ISO/IEC 7498?3ISO/IEC 2022ISO/IEC 7498-3ISO/IEC 7498-1ISO/IEC 7498?1IEC 61131-3ISO/IEC 10731ISO/IEC 646ISO 1177ISO/IEC 8802 (all parts)IEC 61158-1IEC 60870-5-1IEC 61158-6-3IEC 61158-5-3IEC 61784-1ISO/IEC 3309IEC 61784-2Replaces BS EN 61158-4-3:2014 which remains currentAll current amendments available at time of purchase are included with the purchase of this document.