What is BS EN 61158-5-21 - Type 21 application layer service definition about?
BS EN 61158-5-21 is part of a series produced to facilitate the interconnection of automation system components. BS EN 61158-5-21 is related to other standards in the set as defined by the “three-layer” fieldbus reference model described in IEC/TR 61158-1.
BS EN 61158-5-21 provides the common elements for basic time-critical and non-time-critical messaging communications between application programs in an automation environment as well as material specific to the Type 21 protocol. 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 61158-5-21 defines, in an abstract way, the externally visible service provided by the FAL in terms of:
- An abstract model for defining application resources (objects) capable of being manipulated by users via the FAL service
- The primitive actions and events of the service
- The parameters associated with each primitive action and event, and the form that they take
- The interrelationship between these actions and events, and their valid sequences
Who is BS EN 61158-5-21 - Type 21 application layer service definition for?
BS EN 61158-5-21 on industrial communication networks is useful for:
- The IT industry / Software programmers
- The automation industry
- Networking sectors
- Implementors and designers of industrial automation systems
Why should you use BS EN 61158-5-21 - Type 21 application layer service definition?
The application service is provided by the application protocol making use of the services available from the data link or other immediately lower layer.
BS EN 61158-5-21 defines the application service characteristics that fieldbus applications and/or system management may exploit.
BS EN 61158-5-21 specifies the characteristics of conceptual application layer services suitable for time-critical communications, and thus supplements the OSI Basic Reference Model in guiding the development of application layer protocols for time-critical communications.
BS EN 61158-5-21 provides migration paths from previously existing industrial communications protocols.
Overall, the guidance of BS EN 61158-5-21 helps you to gain a better understanding of type 21 fieldbus application layer, this can help you to integrate it into your industrial communication networks and thereby enhance their efficiency.
You can view the latest version of this standard here.
