现场总线应用层（FAL）为用户程序提供访问现场总线通信环境的方法。在这方面，FAL可以被视为“相应应用程序之间的窗口” IEC 61158的这一部分为自动化环境中的应用程序和3型现场总线专用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“时间关键型”用于表示存在一个时间窗口，在该时间窗口内，一个或多个指定动作需要以某种确定的水平完成。如果未能在时间窗口内完成指定的操作，则可能会导致请求操作的应用程序失败，并对设备、工厂以及可能的人身安全造成风险。交叉引用:IEEE 754ISO/IEC 7498- 1ISO/IEC 8822ISO/IEC 10731ISO/IEC 9545ISO/IEC 8824-1EN IEC 61158-5-10:2019IEC 61158-4-3:2019IEC 61158-5-10:2019EN 61158-3-3:2014EN IEC 61158-4-3:2019IEC 61158-5-3:2014EN 61158-5-3:2014IEC 61158-6-10:2019IEC 61158-3-3-3-3:2014IEC 611784-1IEC 61158-3-3-3-3:2014IEC 61158-1IEC 61158-1:2019BS替换EN 61158-3-3-3:2014，所有当前的修订版在购买时均已包括在内这份文件。

The Fieldbus Application Layer (FAL) provides user programs with a means to access the fieldbus communication environment. In this respect, the FAL can be viewed as a "window between corresponding application programs." This part of IEC 61158 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 3 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.Cross References:IEEE 754ISO/IEC 7498-1ISO/IEC 8822ISO/IEC 10731ISO/IEC 9545ISO/IEC 8824-1EN IEC 61158-5-10:2019IEC 61158-4-3:2019IEC 61158-5-10:2019EN 61158-3-3:2014EN IEC 61158-4-3:2019IEC 61158-5-3:2014EN 61158-5-3:2014IEC 61158-6-10:2019IEC 61158-3-3:2014IEC 61784-1IEC 61784-2IEC 61158-1:2019Replaces BS EN 61158-6-3:2014 which remains currentAll current amendments available at time of purchase are included with the purchase of this document.