The Fieldbus Application Layer (FAL) is an Application Layer communication standard designed to support the conveyance of time-critical application requests and responses among 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.