IEC 61158-3-4:20 23为自动化环境中设备之间的基本时间关键消息通信提供了通用元素。术语“时间关键”用于表示时间窗口的存在，在该时间窗口内需要以某种定义的确定性水平完成一个或多个指定的动作。未能在时间窗口内完成指定的操作可能会导致请求操作的应用程序失败，从而给设备、工厂和可能的人的生命带来风险。 本文档以抽象的方式定义了由类型4现场总线数据链路层提供的外部可见服务 服务的原始动作和事件； 与每个原语动作和事件相关联的参数，以及它们采取的形式；和 这些动作和事件之间的相互关系，以及它们的有效顺序。本文档的目的是定义提供给 在现场总线参考模型的应用层和数据链路层之间的边界处的类型4现场总线应用层； 现场总线参考模型的数据链路层和系统管理之间边界的系统管理。

IEC 61158-3-4:2023 provides common elements for basic time-critical messaging communications between devices in an automation environment. The term "time-critical" is used to represent the presence of a time-window, within which one or more specified actions are required to be completed with some defined level of certainty. Failure to complete specified actions within the time window risks failure of the applications requesting the actions, with attendant risk to equipment, plant and possibly human life.
This document defines in an abstract way the externally visible services provided by the Type 4 fieldbus data-link layer in terms of
the primitive actions and events of the services;
the parameters associated with each primitive action and event, and the form which they take; and
the interrelationship between these actions and events, and their valid sequences.
The purpose of this document is to define the services provided to
the Type 4 fieldbus application layer at the boundary between the application and data-link layers of the fieldbus reference model;
systems management at the boundary between the data-link layer and systems management of the fieldbus reference model.