IEC 61158-4-19:20 19规定了用于从一个数据链路用户实体到对等用户实体以及在形成分布式数据链路服务提供商的数据链路实体之间及时传输数据和控制信息的过程，以及用于通过本标准的协议传输数据和控制信息的现场总线DLPDU的结构，以及它们作为物理接口数据单元的表示。第四版取消并取代了2014年出版的第三版，构成技术修订。 主要变化有: ？改进热插拔和冗余功能； ？改进相位切换和错误处理； ？编辑改进

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