What is BS EN 61158-5-9 - Type 9 application layer service definition about?
BS EN 61158-5-9 is part of a series produced to facilitate the interconnection of automation system components. BS EN 61158-5-9 is related to other standards in the set as defined by the “three-layer” fieldbus reference model described in IEC 61158-1 .
BS EN 61158-5-9 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 9 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.
BS EN 61158-5-9 defines in an abstract way the externally visible service provided by the different Types of the 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