1 Scope
1.1 General
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 12 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 International Standard defines in an abstract way the externally visible behavior provided by the different Types of the fieldbus Application Layer in terms of
a) the abstract syntax defining the application layer protocol data units conveyed between communicating application entities,
b...