IEC 61158-5-26:2023为自动化环境中的应用程序和特定于26型现场总线的材料之间的基本时间关键和非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。 本文档从以下方面抽象地定义了Type26现场总线应用层提供的外部可见服务: 用于定义能够由用户经由使用FAL服务来操纵的应用资源(对象)的抽象模型；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。

IEC 61158-5-26:2023 provides common elements for basic time-critical and non-time-critical messaging communications between application programs in an automation environment and material specific to Type 26 fieldbus. 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 service provided by the Type26 fieldbus application layer in terms of:
an abstract model for defining application resources (objects) capable of being manipulated by users via the use of the FAL service;
the primitive actions and events of the service;
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.