工业通信网络 - 现场总线规范 - 第4-19部分:数据链路层协议规范 - 第19类元素

[中文适用范围]： 本国际标准规定了工业通信网络-现场总线规范-第4-19部分：数据链路层协议规范-第19类元素的数据链路层协议。它定义了Type 19元素在数据链路层的通信协议、数据链路协议数据单元（DLPDU）的结构、连接机制、网络拓扑、实时数据通信方法、时标处理、错误处理及监控等。该标准适用于使用Type 19元素构建的工业现场总线网络系统的设计和实现。 [外文原描述]： IEC 61158-4-19:2019 specifies procedures for the timely transfer of data and control information from one data-link user entity to a peer user entity, and among the data-link entities forming the distributed data-link service provider and the structure of the fieldbus 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 fourth edition cancels and replaces the third edition published in 2014 and constitutes a technical revision. The main changes are: •improving the hotplug and redundancy features; •improving the phase switching and the error handling; •editorial improvements