IEC 61158-5-4:2023
(Main)Industrial communication networks - Fieldbus specifications - Part 5-4: Application layer service definition - Type 4 elements
Industrial communication networks - Fieldbus specifications - Part 5-4: Application layer service definition - Type 4 elements
IEC 61158-5-4:2023 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.
Réseaux de communication industriels - Spécifications des bus de terrain - Partie 5-4: Définition des services de la couche application - Éléments de type 4
L'IEC 61158-5-4:2023 fournit des éléments communs pour les communications prioritaires ou non entre des programmes d’application dans un environnement et avec un matériel d’automatisation spécifiques aux bus de terrain de type 4. Le terme "prioritaire" signale l’existence d’une fenêtre temporelle dans laquelle une ou plusieurs actions spécifiées doivent être réalisées, avec un niveau de certitude défini. Si les actions spécifiées ne sont pas réalisées dans la fenêtre temporelle, les applications demandant les actions risquent de connaître une défaillance, avec les risques que cela comporte pour les équipements, les installations et éventuellement la vie humaine.
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IEC 61158-5-4 ®
Edition 4.0 2023-03
INTERNATIONAL
STANDARD
Industrial communication networks – Fieldbus specifications –
Part 5-4: Application layer service definition – Type 4 elements
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IEC 61158-5-4 ®
Edition 4.0 2023-03
INTERNATIONAL
STANDARD
Industrial communication networks – Fieldbus specifications –
Part 5-4: Application layer service definition – Type 4 elements
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 25.040.40; 35.100.70; 35.110 ISBN 978-2-8322-6572-7
– 2 – IEC 61158-5-4:2023 © IEC 2023
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
1.1 General . 7
1.2 Specifications . 8
1.3 Conformance . 8
2 Normative references . 8
3 Terms, definitions, symbols, abbreviated terms and conventions . 9
3.1 ISO/IEC 7498-1 terms . 9
3.2 ISO/IEC 8822 terms . 9
3.3 ISO/IEC 9545 terms . 10
3.4 ISO/IEC 8824-1 terms . 10
3.5 Fieldbus data-link layer terms . 10
3.6 Fieldbus application layer specific definitions . 10
3.7 Abbreviations and symbols . 16
3.8 Conventions . 17
3.8.1 Overview . 17
3.8.2 General conventions . 18
3.8.3 Conventions for class definitions . 18
3.8.4 Conventions for service definitions . 19
4 Concepts . 20
4.1 Overview. 20
4.2 Architectural relationships . 21
4.2.1 Relationship to the Application Layer of the OSI basic reference model . 21
4.2.2 Relationships to other fieldbus entities. 21
4.3 Fieldbus Application Layer structure . 23
4.3.1 Overview . 23
4.3.2 Fundamental concepts . 23
4.3.3 Fieldbus application processes . 23
4.3.4 Application process objects . 27
4.3.5 Application entities . 29
4.3.6 Fieldbus application service elements . 30
4.3.7 Application relationships . 33
4.4 Fieldbus Application Layer naming and addressing . 35
4.4.1 General . 35
4.4.2 Identifying objects accessed through the FAL . 35
4.4.3 Addressing APs accessed through the FAL. 36
4.5 Architecture summary . 36
4.6 FAL service procedures . 36
4.6.1 FAL confirmed service procedures . 36
4.6.2 FAL unconfirmed service procedures . 37
4.7 Common FAL attributes . 37
4.8 Common FAL service parameters . 38
4.9 APDU size . 39
5 Type 4 communication model specification . 39
5.1 Concepts . 39
5.1.1 Overview . 39
5.1.2 Application entities . 39
5.1.3 Gateway and routing . 41
5.1.4 Architecture summary . 42
5.1.5 FAL service procedures and time sequence diagrams . 43
5.2 Variable ASE . 45
5.2.1 Variable types. 45
5.2.2 Variable model class specification . 47
5.2.3 Basic variable type specifications . 48
5.2.4 Constructed variable type specifications . 53
5.2.5 Route endpoint ASE . 57
5.2.6 Route endpoint ASE service specification . 60
5.3 Application relationship ASE . 64
5.3.1 Overview . 64
5.3.2 Application relationship class specification . 64
5.3.3 Application relationship ASE service specifications . 66
Bibliography . 71
Figure 1 – Relationship to the OSI basic reference model . 21
Figure 2 – Architectural positioning of the fieldbus Application Layer . 22
Figure 3 – Client/server interactions. 24
Figure 4 – Pull model interactions . 25
Figure 5 – Push model interactions . 26
Figure 6 – APOs services conveyed by the FAL . 28
Figure 7 – Application entity structure . 29
Figure 8 – Example FAL ASEs . 31
Figure 9 – FAL management of objects . 31
Figure 10 – ASE service conveyance . 32
Figure 11 – Defined and established AREPs . 35
Figure 12 – FAL architectural components . 36
Figure 13 – FAL AE . 40
Figure 14 – Summary of the FAL architecture . 42
Figure 15 – FAL service procedure overview . 43
Figure 16 – Time sequence diagram for the confirmed services . 44
Figure 17 – Time sequence diagram for unconfirmed services . 45
Table 1 – REQUEST service parameters . 60
Table 2 – RESPONSE service parameters . 61
Table 3 – Error codes by source . 62
Table 4 – Reserve REP service parameters . 62
Table 5 – Free AREP service parameters . 63
Table 6 – Get REP attribute service parameters . 63
Table 7 – Set REP attribute service parameters . 64
Table 8 – AR send service parameters. 68
Table 9 – AR acknowledge service parameters . 68
Table 10 – AR get attributes service parameters . 69
Table 11 – AR set attributes service parameters . 69
– 4 – IEC 61158-5-4:2023 © IEC 2023
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 5-4: Application layer service definition –
Type 4 elements
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
Attention is drawn to the fact that the use of the associated protocol type is restricted by its
intellectual-property-right holders. In all cases, the commitment to limited release of intellectual-
property-rights made by the holders of those rights permits a layer protocol type to be used with
other layer protocols of the same type, or in other type combinations explicitly authorized by its
intellectual-property-right holders.
NOTE Combinations of protocol types are specified in IEC 61784-1 series and IEC 61784-2 series.
IEC 61158-5-4 has been prepared by subcommittee 65C: Industrial networks, of IEC technical
committee 65: Industrial-process measurement, control and automation. It is an International
Standard.
This fourth edition cancels and replaces the third edition published in 2019. This edition
constitutes a technical revision.
This edition includes the following significant technical change with respect to the previous
edition:
a) Use of extended data size in an APDU body. This extension is restricted to nodes operating
on a P-NET IP network. There are no technical changes to this sub-part of the standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
65C/1203/FDIS 65C/1244/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all the parts of the IEC 61158 series, under the general title Industrial communication
networks – Fieldbus specifications, can be found on the IEC web site.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
– 6 – IEC 61158-5-4:2023 © IEC 2023
INTRODUCTION
This document is one of a series produced to facilitate the interconnection of automation system
components. It is related to other standards in the set as defined by the "three-layer" fieldbus
reference model described in IEC 61158-1.
The application service is provided by the application protocol making use of the services
available from the data-link or other immediately lower layer. This document defines the
application service characteristics that fieldbus applications and/or system management can
exploit.
Throughout the set of fieldbus standards, the term "service" refers to the abstract capability
provided by one layer of the OSI Basic Reference Model to the layer immediately above. Thus,
the application layer service defined in this document is a conceptual architectural service,
independent of administrative and implementation divisions.
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 5-4: Application layer service definition –
Type 4 elements
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 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 document defines in an abstract way the externally visible service provided by the Type 4
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; and
• the interrelationship between these actions and events, and their valid sequences.
The purpose of this document is to define the services provided to:
• the FAL user at the boundary between the user and the application layer of the fieldbus
reference model, and
• Systems Management at the boundary between the application layer and Systems
Management of the fieldbus reference model.
This document 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.
– 8 – IEC 61158-5-4:2023 © IEC 2023
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
document to provide access to the FAL to control certain aspects of its operation.
1.2 Specifications
The principal objective of this document 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 in subparts of IEC 61158-6.
This document can 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
a) the sizes and octet ordering of various multi-octet service parameters, and
b) the correlation of paired request and confirm, or indication and response, primitives.
1.3 Conformance
This document 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 document.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
NOTE All parts of the IEC 61158 series, as well as IEC 61784-1 series and IEC 61784-2 series are maintained
simultaneously. Cross-references to these documents within the text therefore refer to the editions as dated in this
list of normative references.
IEC 61158-3-4:2023, Industrial communication networks – Fieldbus specifications – Part 3-4:
Data-link layer service definition – Type 4 elements
IEC 61158-4-4:2023, Industrial communication networks – Fieldbus specifications – Part 4-4:
Data-link layer protocol specification – Type 4 elements
IEC 61158-6-4:2023, Industrial communication networks – Fieldbus specifications – Part 6-4:
Application layer protocol specification – Type 4 elements
ISO/IEC 7498-1, Information technology – Open Systems Interconnection – Basic Reference
Model – Part 1: The Basic Model
ISO/IEC 7498-3, Information technology – Open Systems Interconnection – Basic Reference
Model – Part 3: Naming and addressing
ISO/IEC 8822, Information technology – Open Systems Interconnection – Presentation service
definition
ISO/IEC 8824-1, Information technology – Abstract Syntax Notation One (ASN.1) – Part 1:
Specification of basic notation
ISO/IEC 9545, Information technology – Open Systems Interconnection – Application Layer
structure
ISO/IEC 10731, Information technology – Open Systems Interconnection – Basic Reference
Model – Conventions for the definition of OSI services
ISO/IEC 60559, Floating-point arithmetic
3 Terms, definitions, symbols, abbreviated terms and conventions
For the purposes of this document, the following terms, definitions, symbols, abbreviated terms
and conventions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1 ISO/IEC 7498-1 terms
For the purposes of this document, the following terms as defined in ISO/IEC 7498 1 apply:
a) application entity
b) application process
c) application protocol data unit
d) application service element
e) application entity invocation
f) application process invocation
g) application transaction
h) real open system
i) transfer syntax
3.2 ISO/IEC 8822 terms
For the purposes of this document, the following terms as defined in ISO/IEC 8822 apply:
a) abstract syntax
b) presentation context
– 10 – IEC 61158-5-4:2023 © IEC 2023
3.3 ISO/IEC 9545 terms
For the purposes of this document, the following terms as defined in ISO/IEC 9545 apply:
a) application-association
b) application-context
c) application context name
d) application-entity-invocation
e) application-entity-type
f) application-process-invocation
g) application-process-type
h) application-service-element
i) application control service element
3.4 ISO/IEC 8824-1 terms
For the purposes of this document, the following terms as defined in ISO/IEC 8824-1 apply:
a) object identifier
b) type
3.5 Fieldbus data-link layer terms
For the purposes of this document, the following terms apply.
a) DL-Time
b) DL-Scheduling-policy
c) DLCEP
d) DLC
e) DLPDU
f) DLSDU
g) DLSAP
h) fixed tag
i) generic tag
j) link
k) network address
l) node address
m) node
n) tag
o) scheduled
p) unscheduled
3.6 Fieldbus application layer specific definitions
For the purposes of this document, the following terms and definitions apply.
3.6.1
application
function or data structure for which data is consumed or produced
3.6.2
application objects
multiple object classes that manage and provide a run time exchange of messages across the
network and within the network device
3.6.3
application process
part of a distributed application on a network, which is located on one device and unambiguously
addressed
3.6.4
application process identifier
value that distinguishes an application process among multiple application processes used in a
device
3.6.5
application process object
component of an application process that is identifiable and accessible through an FAL
application relationship
Note 1 to entry: Application process object definitions are composed of a set of values for the attributes of their
class (see the definition for Application Process Object Class Definition). Application process object definitions can
be accessed remotely using the services of the FAL Object Management ASE. FAL Object Management services can
be used to load or update object definitions, to read object definitions, and to dynamically create and delete
application objects and their corresponding definitions.
3.6.6
application process object class
class of application process objects defined in terms of the set of their network-accessible
attributes and services
3.6.7
application relationship
cooperative association between two or more application-entity-invocations for the purpose of
exchange of information and coordination of their joint operation
Note 1 to entry: This relationship is activated either by the exchange of application-protocol-data-units or as a result
of preconfiguration activities.
3.6.8
application relationship application service element
application-service-element that provides the exclusive means for establishing and terminating
all application relationships
3.6.9
application relationship endpoint
context and behavior of an application relationship as seen and maintained by one of the
application processes involved in the application relationship
Note 1 to entry: Each application process involved in the application relationship maintains its own application
relationship endpoint.
3.6.10
attribute
description of an externally visible characteristic or feature of an object
Note 1 to entry: The attributes of an object contain information about variable portions of an object. Typically, they
provide status information or govern the operation of an object. Attributes can also affect the behavior of an object.
Attributes are divided into class attributes and instance attributes.
– 12 – IEC 61158-5-4:2023 © IEC 2023
3.6.11
behavior
indication of how an object responds to particular events
3.6.12
bit-no
number of a bit in a bitstring or an octet
3.6.13
channel
single physical or logical link of an input or output application object of a server to the process
3.6.14
class
set of objects, all of which represent the same kind of system component
Note 1 to entry: A class is a generalisation of an object; a template for defining variables and methods. All objects
in a class are identical in form and behavior, but usually contain different data in their attributes.
3.6.15
class attributes
attribute that is shared by all objects within the same class
3.6.16
class code
unique identifier assigned to each object class
3.6.17
class specific service
service defined by a particular object class to perform a required function which is not performed
by a common service
Note 1 to entry: A class specific object is unique to the object class which defines it.
3.6.18
client
object which uses the services of another (server) object to perform a task
3.6.19
client
initiator of a message to which a server reacts
3.6.20
communication objects
components that manage and provide a run time exchange of messages across the network
EXAMPLES: Connection Manager object, Unconnected Message Manager (UCMM) object, and Message Router
object.
3.6.21
connection
logical binding between application objects that may be within the same or different devices
Note 1 to entry: Connections may be either point-to-point or multipoint.
3.6.22
conveyance path
unidirectional flow of APDUs across an application relationship
3.6.23
dedicated AR
AR used directly by the FAL User
Note 1 to entry: On Dedicated ARs, only the FAL Header and the user data are transferred.
3.6.24
default DL-address
value 126 as an initial value for DL-address, which has to be changed (e.g. by assignment of a
DL-address via the fieldbus) before operation with a DP-master (class 1)
3.6.25
device
physical hardware connected to the link
Note 1 to entry: A device may contain more than one node.
3.6.26
dynamic AR
AR that requires the use of the AR establishment procedures to place it into an established
state
3.6.27
endpoint
one of the communicating entities involved in a connection
3.6.28
error
discrepancy between a computed, observed or measured value or condition and the specified
or theoretically correct value or condition
3.6.29
error class
general grouping for related error definitions and corresponding error codes
3.6.30
error code
identification of a specific type of error within an error class
3.6.31
event
instance of a change of conditions
3.6.32
FAL subnet
subnetworks composed of one or more data link segments, identified by a subset of the network
address
Note 1 to entry: FAL subnets are permitted to contain bridges but not routers.
3.6.33
FIFO variable
Variable Object class, composed of a set of homogeneously typed elements, where the first
written element is the first element that can be read.
Note 1 to entry: On the fieldbus only one, complete element can be transferred as a result of one service invocation.
3.6.34
frame
deprecated synonym for DLPDU
– 14 – IEC 61158-5-4:2023 © IEC 2023
3.6.35
interface
shared boundary between two functional units, defined by functional
characteristics, signal characteristics, or other characteristics as appropriate
3.6.36
interface
collection of FAL class attributes and services that represents a
specific view on the FAL class
3.6.37
invocation
act of using a service or other resource of an application process
Note 1 to entry: Each invocation represents a separate thread of control that can be described by its context. Once
the service completes, or use of the resource is released, the invocation ceases to exist. For service invocations, a
service that has been initiated but not yet completed is referred to as an outstanding service invocation. Also for
service invocations, an Invoke ID may be used to unambiguously identify the service invocation and differentiate it
from other outstanding service invocations.
3.6.38
index
address of an object within an application process
3.6.39
instance
actual physical occurrence of an object within a class that identifies one of many objects within
the same object class
EXAMPLE California is an instance of the object class state.
Note 1 to entry: The terms object, instance, and object instance are used to refer to a specific instance.
3.6.40
instance attributes
attribute that is unique to an object instance and not shared by the object class
3.6.41
instantiated
object that has been created in a device
3.6.42
logical device
certain FAL class that abstracts a software component or a firmware component as an
autonomous self-contained facility of an automation device
3.6.43
manufacturer ID
identification of each product manufacturer by a unique number
3.6.44
management information
network-accessible information that supports managing the operation of the fieldbus system,
including the application layer
Note 1 to entry: Managing includes functions such as controlling, monitoring, and diagnosing.
3.6.45
member
piece of an attribute that is structured as an element of an array
3.6.46
method
a synonym for an operational service which is provided by the server ASE and invoked
by a client
3.6.47
module
hardware or logical component of a physical device
3.6.48
network
set of nodes connected by some type of communication medium, including any intervening
repeaters, bridges, routers and lower-layer gateways
3.6.49
object
abstract representation of a particular component within a device, usually a collection of related
data (in the form of variables) and methods (procedures) for operating on that data that have
clearly defined interface and behavior
3.6.50
object specific service
service unique to the object class which defines it
3.6.51
peer
role of an AR endpoint in which it is capable of acting as both client and server
3.6.52
physical device
automation or other network device
3.6.53
property
general term for descriptive information about an object
3.6.54
provider
source of a data connection
3.6.55
publisher
role of an AR endpoint that transmits APDUs onto the fieldbus for consumption by one or more
subscribers
Note 1 to entry: A publisher is possible aware of the identity or the number of subscribers, or not and it can publish
its APDUs using a dedicated AR.
3.6.56
publishing manager
role of an AR endpoint in which it issues one or more confirmed service request APDUs to a
publisher to request the publisher to publish a specified object
Note 1 to entry: Two types of publishing managers are defined by this document, pull publishing managers and
push publishing managers, each of which is defined separately
– 16 – IEC 61158-5-4:2023 © IEC 2023
3.6.57
pull subscriber
type of subscriber that recognizes received confirmed service response APDUs as published
object data
3.6.58
resource
processing or information capability of a subsystem
3.6.59
route endpoint
object container containing Variable Objects of a variable class
3.6.60
server
role of an AREP in which it returns a confirmed service response
APDU to the client that initiated the request
3.6.61
server
object which provides services to another (client) object
3.6.62
service
operation or function than an object and/or object class performs upon request from another
object and/or object class
3.6.63
subscriber
role of an AREP in which it receives APDUs produced by a publisher
3.7 Abbreviations and symbols
AE Application Entity
AL Application Layer
ALME Application Layer Management Entity
ALP Application Layer Protocol
APO Application Object
AP Application Process
APDU Application Protocol Data Unit
API Application Process Identifier
AR Application Relationship
AREP Application Relationship End Point
ASCII American Standard Code for Information Interchange
ASE Application Service Element
Cnf Confirmation
CR Communication Relationship
CREP Communication Relationship End Point
DL- (as a prefix) Data Link-
DLC Data Link Connection
DLCEP Data Link Connection End Point
DLL Data Link Layer
DLM Data Link-management
DLSAP Data Link Service Access Point
DLSDU DL-service-data-unit
DNS Domain Name Service
DP Decentralised Peripherals
FAL Fieldbus Application Layer
FIFO First In First Out
HMI Human-Machine Interface
ID Identifier
IDL Interface Definition Language
IEC International Electrotechnical Commission
Ind Indication
IP Internet Protocol
ISO International Organization for Standardization
LDev Logical Device
LME Layer Management Entity
OSI Open Systems Interconnect
PDev Physical Device
PDU Protocol Data Unit
PL Physical Layer
QoS Quality of Service
REP Route Endpoint
Req Request
Rsp Response
RT Runtime
SAP Service Access Point
SCL Security Level
SDU Service Data Unit
SEM State event matrix
SMIB System Management Information Base
SMK System Management Kernel
STD State transition diagram, used to describe object behavior
VAO Variable Object
3.8 Conventions
3.8.1 Overview
The FAL is defined as a set of object-oriented ASEs. Each ASE is specified in a separate
subclause. Each ASE specification is composed of two parts, its class specification, and its
service specification.
The class specification defines the attributes of the class. The attributes are accessible from
instances of the class using the Object Management ASE services specified in Clause 5 of this
document. The service specification defines the services that are provided by the ASE.
– 18 – IEC 61158-5-4:2023 © IEC 2023
3.8.2 General conventions
This document uses the descriptive conventions given in ISO/IEC 10731.
3.8.3 Conventions for class definitions
Class definitions are described using templates. Each template consists of a list of attributes
for the class. The general form of the template is shown below:
FAL ASE: ASE Name
CLASS: Class Name
CLASS ID: #
PARENT CLASS: Parent Class Name
ATTRIBUTES:
1 (o) Key Attribute: numeric identifier
2 (o) Key Attribute: name
3 (m) Attribute: attribute name(values)
4 (m) Attribute: attribute name(values)
4.1 (s) Attribute: attribute name(values)
4.2 (s) Attribute: attribute name(values)
4.3 (s) Attribute: attribute name(values)
5. (c) Constraint: constraint expression
5.1 (m) Attribute: attribute name(values)
5.2 (o) Attribute: attribute name(values)
6 (m) Attribute: attribute name(values)
6.1 (s) Attribute: attribute name(values)
6.2 (s) Attribute: attribute name(values)
SERVICES:
1 (o) OpsService: service name
2. (c) Constraint: constraint expression
2.1 (o) OpsService: service name
3 (m) MgtService: service name
1) The "FAL ASE:" entry is the name of the FAL ASE that provides the services for the class
being specified.
2) The "CLASS:" entry is the name of the class being specified. All objects defined using this
template will be an instance of this class. The class may be specified by this document, or
by a user of this document.
3) The "CLASS ID:" entry is a number that identifies the class being specified. This number is
unique within the FAL ASE that will provide the services for this class. When qualified by
the identity of its FAL ASE, it unambiguously identifies the class within the scope of the FAL.
The value "NULL" indic
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