BS EN 61158-5-12:2014

What is BS EN 61158-5-12 – Type 12 application layer service definition about?  

BS EN 61158-5-12 is part of a series produced to facilitate the interconnection of automation system components. BS EN 61158-5-12 is related to other standards in the set as defined by the “three-layer” fieldbus reference model described in IEC 61158-1. 

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.” 

BS EN 61158-5-12 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. 

BS EN 61158-5-12 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 
• The interrelationship between these actions and events, and their valid sequences 

Who is BS EN 61158-5-12 – Type 12 application layer service definition for? 

BS EN 61158-5-12 on industrial communication networks is useful for: 

• The IT industry / Software programmers  
• Internet engineering task forces    
• The automation industry  
• Networking sectors  
• Implementors and designers of industrial automation systems 

Why should you use BS EN 61158-5-12 – Type 12 application layer service definition?  

FAL services and protocols are provided by FAL application entities (AE) contained within the application processes. The FAL AE is composed of a set of object-oriented Application Service Elements (ASEs) and a Layer Management Entity (LME) that manages the AE. The ASEs provide communication services that operate on a set of related application process object (APO) classes.  

BS EN 61158-5-12 specifies the characteristics of conceptual application layer services suitable for time-critical communications, and thus supplement the OSI Basic Reference Model in guiding the development of application layer protocols for time-critical communications. 

BS EN 61158-5-12 provides migration paths from previously-existing industrial communications protocols. BS EN 61158-5-12 may be used as the basis for formal Application Programming-Interfaces. Using BS EN 61158-5-12 guidelines, you are in a position to facilitate industrial automation that accelerates productivity. 

You can view the latest version of this standard here.