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BS EN 61158-5-4:2014

$215.11

Industrial communication networks. Fieldbus specifications – Application layer service definition. Type 4 elements

Published By Publication Date Number of Pages
BSI 2014 76
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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 standard 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 4 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 standard defines in an abstract way the externally visible service provided by the Type 4 fieldbus application layer in terms of

  1. an abstract model for defining application resources (objects) capable of being manipulated by users via the use of the FAL service,

  2. the primitive actions and events of the service;

  3. the parameters associated with each primitive action and event, and the form which they take; and

  4. the interrelationship between these actions and events, and their valid sequences.

The purpose of this standard is to define the services provided to

  1. the FAL user at the boundary between the user and the application layer of the fieldbus reference model, and

  2. Systems Management at the boundary between the application layer and Systems Management of the fieldbus reference model.

This standard specifies the structure and services of the Type 4 fieldbus application layer, in conformance with the OSI Basic Reference Model (ISO/IEC 7498-1) and the OSI application layer structure (ISO/IEC 9545).

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. One of the FAL ASEs is a management ASE that provides a common set of services for the management of the instances of FAL classes.

Although these services specify, from the perspective of applications, how request and responses are issued and delivered, they do not include a specification of what the requesting and responding applications are to do with them. That is, the behavioral aspects of the applications are not specified; only a definition of what requests and responses they can send/receive is specified. This permits greater flexibility to the FAL users in standardizing such object behavior. In addition to these services, some supporting services are also defined in this standard to provide access to the FAL to control certain aspects of its operation.

1.2 Specifications

The principal objective of this standard is to specify 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.

A secondary objective is to provide migration paths from previously-existing industrial communications protocols. It is this latter objective which gives rise to the diversity of services standardized as the various Types of IEC 61158, and the corresponding protocols standardized in IEC 61158-6 series.

This specification may be used as the basis for formal application programming interfaces. Nevertheless, it is not a formal programming interface, and any such interface will need to address implementation issues not covered by this specification, including

  1. the sizes and octet ordering of various multi-octet service parameters, and

  2. the correlation of paired request and confirm, or indication and response, primitives.

1.3 Conformance

This standard does not specify individual implementations or products, nor does it constrain the implementations of application layer entities within industrial automation systems.

There is no conformance of equipment to this application layer service definition standard. Instead, conformance is achieved through implementation of conforming application layer protocols that fulfill the Type 2 application layer services as defined in this standard.

PDF Catalog

PDF Pages PDF Title
7 English

CONTENTS
9 INTRODUCTION
10 1 Scope
1.1 General
11 1.2 Specifications
1.3 Conformance
2 Normative references
12 3 Terms and definitions
3.1 ISO/IEC 7498-1 terms
3.2 ISO/IEC 8822 terms
3.3 ISO/IEC 9545 terms
13 3.4 ISO/IEC 8824-1 terms
3.5 Fieldbus data-link layer terms
3.6 Fieldbus application layer specific definitions
19 3.7 Abbreviations and symbols
20 3.8 Conventions
23 4 Concepts
4.1 Overview
24 4.2 Architectural relationships
Figures

Figure 1 – Relationship to the OSI basic reference model
25 Figure 2 – Architectural positioning of the fieldbus Application Layer
26 4.3 Fieldbus Application Layer structure
27 Figure 3 – Client/server interactions
28 Figure 4 – Pull model interactions
29 Figure 5 – Push model interactions
30 Figure 6 – APOs services conveyed by the FAL
32 Figure 7 – Application entity structure
33 Figure 8 – Example FAL ASEs
34 Figure 9 – FAL management of objects
35 Figure 10 – ASE service conveyance
37 Figure 11 – Defined and established AREPs
38 4.4 Fieldbus Application Layer naming and addressing
4.5 Architecture summary
39 4.6 FAL service procedures
Figure 12 – FAL architectural components
40 4.7 Common FAL attributes
4.8 Common FAL service parameters
41 4.9 APDU size
5 Type 4 communication model specification
5.1 Concepts
42 Figure 13 – FAL AE
45 Figure 14 – Summary of the FAL architecture
46 Figure 15 – FAL service procedure overview
47 Figure 16 – Time sequence diagram for the confirmed services
48 5.2 Variable ASE
Figure 17 – Time sequence diagram for unconfirmed services
63 Tables

Table 1 – REQUEST service parameters
64 Table 2 – RESPONSE service parameters
65 Table 3 – Error codes by source
Table 4 – Reserve REP service parameters
66 Table 5 – Free AREP service parameters
Table 6 – Get REP attribute service parameters
67 5.3 Application relationship ASE
Table 7 – Set REP attribute service parameters
71 Table 8 – AR send service parameters
Table 9 – AR acknowledge service parameters
72 Table 10 – AR get attributes service parameters
Table 11 – AR set attributes service parameters
74 Bibliography
BS EN 61158-5-4:2014
$215.11