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。 该协议为所有参与的数据链路实体提供通信机会a）根据预先建立的时间表以同步启动循环方式，b）根据这些数据链路实体中的每个周期的请求以循环或非循环异步方式。 因此，该协议可以被描述为一个异步提供循环和非循环访问的协议，但每个循环都有一个同步重启。交叉引用:IEC 61158-4-16:2007EN 61158-4-16:2008ISO/IEC 7498-3IEEE标准802.3ISO/IEC/IEEE 8802-3RFC 879ISO/IEC 7498-1IEE 802.3ISO 8601EN 61158-6-19EN 61158- 3-19IEC 61158-5-19IEC 61784-2EN 61784-2IEC 61131IEC 61800-7-20x1IEC 61158-6-19IEC 61131（所有零件）IEC 61800-7EN 61800-7EN 61158-5-16IEC 61158-3-19EN 61158-1IEC 611784-1IEC 61158-6-16EN 611784-1IEC 61158-1EN 61158-5-19IEC 61158-6-16EN 61131IEC 61800-7（所有零件）取代BS EN 61158-4-19:2014，目前所有的修订版均随购买时提供购买本文件。

The data-link layer provides basic time-critical messaging communications between devices in an automation environment. This protocol provides communication opportunities to all participating data-link entitiesa) in a synchronously-starting cyclic manner, according to a pre-established schedule, andb) in a cyclic or acyclic asynchronous manner, as requested each cycle by each of those data-link entities. Thus this protocol can be characterized as one which provides cyclic and acyclic access asynchronously but with a synchronous restart of each cycle.Cross References:IEC 61158-4-16:2007EN 61158-4-16:2008ISO/IEC 7498-3IEEE Std 802.3ISO/IEC/IEEE 8802-3RFC 879ISO/IEC 7498-1IEEE 802.3ISO 8601EN 61158-6-19EN 61158-3-19IEC 61158-5-19IEC 61784-2EN 61784-2IEC 61131IEC 61800-7-20x1IEC 61158-6-19IEC 61131 (all parts)IEC 61800-7EN 61800-7EN 61158-5-16IEC 61158-3-19EN 61158-1IEC 61784-1IEC 61158-5-16EN 61158-6-16EN 61784-1IEC 61158-1EN 61158-5-19IEC 61158-6-16EN 61131IEC 61800-7 (all parts)Replaces BS EN 61158-4-19:2014 which remains currentAll current amendments available at time of purchase are included with the purchase of this document.