IEC 61158-5-24:2014

IEC 61158-5-24 ®
Edition 1.0 2014-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Industrial communication networks – Fieldbus specifications –
Part 5-24: Application layer service definition – Type-24 elements

Réseaux de communication industriels – Spécifications des bus de terrain –
Partie 5-24: Définition des services de la couche application – Éléments
de type 24
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite
ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie
et les microfilms, sans l'accord écrit de l'IEC ou du Comité national de l'IEC du pays du demandeur. Si vous avez des
questions sur le copyright de l'IEC ou si vous désirez obtenir des droits supplémentaires sur cette publication, utilisez
les coordonnées ci-après ou contactez le Comité national de l'IEC de votre pays de résidence.

IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé Fax: +41 22 919 03 00
CH-1211 Geneva 20 info@iec.ch
Switzerland www.iec.ch
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.

IEC Catalogue - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
The stand-alone application for consulting the entire The world's leading online dictionary of electronic and
bibliographical information on IEC International Standards, electrical terms containing more than 30 000 terms and
Technical Specifications, Technical Reports and other definitions in English and French, with equivalent terms in 14
documents. Available for PC, Mac OS, Android Tablets and additional languages. Also known as the International
iPad. Electrotechnical Vocabulary (IEV) online.

IEC publications search - www.iec.ch/searchpub IEC Glossary - std.iec.ch/glossary
The advanced search enables to find IEC publications by a More than 55 000 electrotechnical terminology entries in
variety of criteria (reference number, text, technical English and French extracted from the Terms and Definitions
committee,…). It also gives information on projects, replaced clause of IEC publications issued since 2002. Some entries
and withdrawn publications. have been collected from earlier publications of IEC TC 37,

77, 86 and CISPR.
IEC Just Published - webstore.iec.ch/justpublished
Stay up to date on all new IEC publications. Just Published IEC Customer Service Centre - webstore.iec.ch/csc
details all new publications released. Available online and If you wish to give us your feedback on this publication or
also once a month by email. need further assistance, please contact the Customer Service
Centre: csc@iec.ch.
A propos de l'IEC
La Commission Electrotechnique Internationale (IEC) est la première organisation mondiale qui élabore et publie des
Normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.

A propos des publications IEC
Le contenu technique des publications IEC est constamment revu. Veuillez vous assurer que vous possédez l’édition la
plus récente, un corrigendum ou amendement peut avoir été publié.

Catalogue IEC - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
Application autonome pour consulter tous les renseignements
Le premier dictionnaire en ligne de termes électroniques et
bibliographiques sur les Normes internationales,
électriques. Il contient plus de 30 000 termes et définitions en
Spécifications techniques, Rapports techniques et autres
anglais et en français, ainsi que les termes équivalents dans
documents de l'IEC. Disponible pour PC, Mac OS, tablettes
14 langues additionnelles. Egalement appelé Vocabulaire
Android et iPad.
Electrotechnique International (IEV) en ligne.

Recherche de publications IEC - www.iec.ch/searchpub
Glossaire IEC - std.iec.ch/glossary
Plus de 55 000 entrées terminologiques électrotechniques, en
La recherche avancée permet de trouver des publications IEC
en utilisant différents critères (numéro de référence, texte, anglais et en français, extraites des articles Termes et
comité d’études,…). Elle donne aussi des informations sur les Définitions des publications IEC parues depuis 2002. Plus
projets et les publications remplacées ou retirées. certaines entrées antérieures extraites des publications des

CE 37, 77, 86 et CISPR de l'IEC.
IEC Just Published - webstore.iec.ch/justpublished

Service Clients - webstore.iec.ch/csc
Restez informé sur les nouvelles publications IEC. Just
Published détaille les nouvelles publications parues. Si vous désirez nous donner des commentaires sur cette
Disponible en ligne et aussi une fois par mois par email. publication ou si vous avez des questions contactez-nous:
csc@iec.ch.
IEC 61158-5-24 ®
Edition 1.0 2014-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Industrial communication networks – Fieldbus specifications –

Part 5-24: Application layer service definition – Type-24 elements

Réseaux de communication industriels – Spécifications des bus de terrain –

Partie 5-24: Définition des services de la couche application – Éléments

de type 24
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XD
ICS 25.040.40; 35.100.70; 35.110 ISBN 978-2-8322-1744-3

– 2 – IEC 61158-5-24:2014 © IEC 2014
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
1.1 General . 8
1.2 Specifications . 9
1.3 Conformance . 9
2 Normative references . 9
3 Terms, definitions, symbols, abbreviations, and conventions . 10
3.1 Referenced terms and definitions . 10
3.2 Additional terms and definitions . 10
3.3 Abbreviations and symbols . 15
3.4 Conventions . 17
4 Concepts . 19
5 Data type ASE . 20
6 Communication model specifications . 20
6.1 Type specific concepts . 20
6.2 Overview . 20
6.3 FSM ASE . 23
6.4 FAL ASEs. 29
6.5 FAL ARs . 70
Bibliography . 95

Figure 1 – FAL ASE model of Type 24 . 22
Figure 2 – AR model for field device control service . 72
Figure 3 – AR model for message service . 72
Figure 4 – MSG ARs between each APs . 73

Table 1 – AP type definition . 21
Table 2 – Support list of service for each class of FSM ASE . 24
Table 3 – FSM-Reset . 25
Table 4 – FSM-GetStatus . 26
Table 5 – FSM-SetContext . 27
Table 6 – FSM-GetContext . 28
Table 7 – FSM-Start . 28
Table 8 – Support list of service for each class of FDC ASE . 29
Table 9 – FDC-Reset for master class . 33
Table 10 – FDC-Open for master class . 33
Table 11 – FDC-Enable for master class . 34
Table 12 – FDC-Connect for master class . 34
Table 13 – FDC-SyncSet for master class . 35
Table 14 – FDC-Disconnect for master class . 36
Table 15 – FDC-ResumeCycle for master class . 37
Table 16 – FDC-ComCycle for master class . 37

Table 17 – FDC-Command for master class . 38
Table 18 – FDC-DataExchange for master class . 39
Table 19 – FDC-Reset for slave class . 42
Table 20 – FDC-Open for slave class . 43
Table 21 – FDC-Enable for slave class . 43
Table 22 – FDC-Connect for slave class . 44
Table 23 – FDC-SyncSet for slave class . 45
Table 24 – FDC-Disconnect for slave class . 46
Table 25 – FDC-ResumeCycle for slave class . 47
Table 26 – FDC-ComCycle for slave class . 47
Table 27 – FDC-Command for slave class . 48
Table 28 – FDC-Command for slave class . 49
Table 29 – FDC-Reset for monitor class . 51
Table 30 – FDC-Open for monitor class . 51
Table 31 – FDC-Enable for monitor class . 52
Table 32 – FDC-GetCMD for monitor class . 52
Table 33 – FDC-GetRSP for monitor class . 53
Table 34 – Support list of service for each class of Message ASE . 54
Table 35 – MSG-Reset for requester class . 56
Table 36 – MSG-Open for requester class . 57
Table 37 – MSG-Enable for requester class . 57
Table 38 – MSG-UserMessage for requester class . 58
Table 39 – MSG-OnewayMessage for requester class . 59
Table 40 – MSG-AbortTransaction for requester class . 61
Table 41 – MSG-Reset for responder class . 62
Table 42 – MSG-Open for responder class . 63
Table 43 – MSG-Enable for responder class . 63
Table 44 – MSG-UserMessage for responder class . 64
Table 45 – MSG-OnewayMessage for responder class . 65
Table 46 – MSG-AbortTransaction for responder class . 66
Table 47 – Support list of service for each class of Event Management ASE. 67
Table 48 – EVM-Reset . 68
Table 49 – EVM-Enable . 68
Table 50 – EVM-SyncEvent . 69
Table 51 – EVM-ReadNetClock . 69
Table 52 – Support list of service for each class of AR ASE . 70
Table 53 – AR-Reset for FDC Master AR class . 75
Table 54 – AR-Open for FDC Master AR class . 76
Table 55 – AR-Enable for FDC Master AR class . 76
Table 56 – AR-CycleEvent for FDC Master AR class. 77
Table 57 – AR-StartComCycle for FDC Master AR class . 77
Table 58 – AR-ResetCycle for FDC Master AR class . 78
Table 59 – AR-SendCommand for FDC Master AR class . 78

– 4 – IEC 61158-5-24:2014 © IEC 2014
Table 60 – AR-Reset for FDC Slave AR class . 81
Table 61 – AR-Open for FDC Slave AR class . 81
Table 62 – AR-Enable for FDC Slave AR class . 82
Table 63 – AR-CycleEvent for FDC Slave AR class . 82
Table 64 – AR-StartComCycle for FDC Slave AR class . 83
Table 65 – AR-ResetCycle for FDC Slave AR class . 83
Table 66 – AR-SendCommand for FDC Slave AR class . 84
Table 67 – AR-Reset for FDC Monitor AR class . 86
Table 68 – AR-Open for FDC Monitor AR class . 86
Table 69 – AR-Enable for FDC Monitor AR class . 87
Table 70 – AR-GetCMD for FDC Monitor AR class . 88
Table 71 – AR-GetCMD for FDC Monitor AR class . 88
Table 72 – AR-Reset for Message AR class . 90
Table 73 – AR-Open for Message AR class . 91
Table 74 – AR-Enable for Message AR class . 92
Table 75 – AR-SendMessage for Message AR class . 92
Table 76 – AR-ReceiveMessage for Message AR class . 93
Table 77 – AR-AbortMessage for Message AR class . 94

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 5-24: Application layer service definition –
Type-24 elements
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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 and IEC 61784-2.
International Standard IEC 61158-5-24 has been prepared by subcommittee 65C: Industrial
networks, of IEC technical committee 65: Industrial-process measurement, control and
automation.
– 6 – IEC 61158-5-24:2014 © IEC 2014
The text of this standard is based on the following documents:
FDIS Report on voting
65C/763/FDIS 65C/773/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the IEC 61158 series, published 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 publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
INTRODUCTION
This part of IEC 61158 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 standard defines the
application service characteristics that fieldbus applications and/or system management may
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 standard is a conceptual architectural service,
independent of administrative and implementation divisions.

– 8 – IEC 61158-5-24:2014 © IEC 2014
INDUSTRIAL COMMUNICATION NETWORKS –
FIELDBUS SPECIFICATIONS –
Part 5-24: Application layer service definition –
Type-24 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 International 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 24 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 International Standard defines in an abstract way the externally visible service provided
by the different Types of fieldbus Application Layer in terms of
a) an abstract model for defining application resources (objects) capable of being
manipulated by users via the use of the FAL service,
b) the primitive actions and events of the service,
c) the parameters associated with each primitive action and event, and the form which they
take, and
d) the interrelationship between these actions and events, and their valid sequences.
The purpose of this International Standard is to define the services provided to
a) the FAL user at the boundary between the user and the Application Layer of the Fieldbus
Reference Model, and
b) Systems Management at the boundary between the Application Layer and Systems
Management of the Fieldbus Reference Model.
This International Standard specifies the structure and services of the IEC 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 International 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 subparts of IEC 61158-6.
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
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 standard does not specify individual implementations or products, nor do they 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 fulfil any given Type of application layer services as defined in this part of
IEC 61158.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. 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 and IEC 61784-2 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 61158-1:2014, Industrial communication networks – Fieldbus specifications – Part 1:
Overview and guidance for the IEC 61158 and IEC 61784 series
IEC 61158-6-24:2014, Industrial communication networks – Fieldbus specifications –
Part 6-24: Application layer protocol specification – Type 24 elements
ISO/IEC 7498-1, Information technology – Open Systems Interconnection – Basic Reference
Model – Part 1: The Basic Model
ISO/IEC 8824-1, Information technology – Abstract Syntax Notation One (ASN.1):
Specification of basic notation
ISO/IEC 9545, Information technology – Open Systems Interconnection – Application Layer
structure
– 10 – IEC 61158-5-24:2014 © IEC 2014
ISO/IEC 10731, Information technology – Open Systems Interconnection – Basic Reference
Model – Conventions for the definition of OSI services
3 Terms, definitions, symbols, abbreviations, and conventions
For the purposes of this document, the following terms, definitions, symbols, abbreviations
and conventions apply.
3.1 Referenced terms and definitions
3.1.1 ISO/IEC 7498-1 terms
For the purposes of this document, the following terms as defined in ISO/IEC 7498-1 apply:
a) abstract syntax;
b) application-entity;
c) application process;
d) application protocol data unit;
e) application-process-invocation;
f) (N)-facility;
g) (N)-function;
h) correspondent-(N)-entities;
i) presentation context;
j) real system;
k) transfer syntax.
3.1.2 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-entity-invocation;
d) application-entity-type;
e) application-service-element.
3.1.3 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.
3.1.4 Terms and definitions from ISO/IEC 10731
For the purposes of this document, the following terms as defined in ISO/IEC 10731 apply:
a) OSI-service-primitive; primitive;
b) OSI-service-provider; provider;
c) OSI-service-user; user.
3.2 Additional terms and definitions
For the purposes of this document, the following terms and definitions apply.

3.2.1
alarm
field device status to tell that the device has detected a fatal problem to be solved and cannot
continue normal working, through the field device control (FDC) service of the type 24 fieldbus
Note 1 to entry:  Any alarm statuses are latched and need some operation to be cleared them.
Note 2 to entry:  Alarms may be classified into three groups; communication alarms, illegal-command-related ones,
and application specific ones. But concrete definitions are dependent on implementation of each field devices.
3.2.2
application process object
network representation of a specific aspect of an application process (AP), which is modelled
as a network accessible object contained within an AP or within another APO
Note 1 to entry:  Refer IEC 61158-1, 9.3.4.
3.2.3
application process context
AP context
shared knowledge or a common set of rules, governing communication of FAL application
entities (AEs) and describing the permissible collective communications behavior between the
AEs that are party to a specific set of application relationships (ARs)
Note 1 to entry:  Data within AP context can be specified by the user in advance, by the option selected while the
user uses a field bus management (FSM) service to read out the facility of peer AP, by the automatic negotiation
function that the FSM system handles, and so on. The method that is to be adopted depends on the specification of
each implementation.
3.2.4
application process type
AP type
description of a classification of application processes (APs) in terms of a set of capabilities
for FAL of the type 24 fieldbus
Note 1 to entry:  AP types are classified into three ones, C1 master AP, C2 master AP and slave AP, by their
application roles in the fieldbus network. See 6.2.
3.2.5
async command
type of a command application protocol data unit (APDU) of the FDC service of the type 24
FAL, which can be issued any time after the previous transaction without consideration of
synchronization with the communication cycle
Note 1 to entry:  Definitions, which command should be async one or not, are dependent on an application. They
may be provided as a registered set of commands and responses or a device profiles (see IEC 61158-6-24:2014,
4.4 and Annex A).
3.2.6
asynchronous communication
state or a way of communication for the FDC service of the type 24 FAL, in which a command
can be issued any time after the previous transaction without consideration of synchronization
with the communication cycle
Note 1 to entry:  In this state, sync commands cannot be issued, but async commands can.
3.2.7
attribute
information or parameter contained in variable portions of an object
Note 1 to entry:  Typically, they provide status information or govern the operation of an object. Attributes may
also affect the behaviour of an object.

– 12 – IEC 61158-5-24:2014 © IEC 2014
3.2.8
C1 master
AP type that has master facilities for the FDC service of the type 24 FAL, or the device
implementing that AP type
Note 1 to entry:  Only one C1 master exists in a network of the type 24 fieldbus
3.2.9
C2 master
AP type that has only monitor facilities for the FDC service but requester facilities for
message (MSG) service of the type 24 FAL, or the device implementing that AP type
Note 1 to entry:  Less than two C2 masters can exist in a network of the type 24 fieldbus
3.2.10
command
PDU issued by a requester or a master to make a responder or a slave execute some
functions
3.2.11
communication
transfer
transmission
– communication: process to exchange information in a formal manner between two or
more devices, users, APs or entities
– transfer: process to convey a PDU from a sender to a receiver
– transmission: process to send out and propagate electrical signals or encoded data
3.2.12
communication cycle
period of repetitive activities synchronized with the transmission cycle while the connection
establishing for the FDC protocol of the type 24 FAL
Note 1 to entry:  Communication cycle may synchronize with a cycle multiplying the transmission cycle by a
specified scaling factor.
3.2.13
connection
context or logical binding under specific conditions for the FDC protocol between a master
object and a slave object for the type 24 FAL
3.2.14
cyclic
repetitive in a regular manner
3.2.15
cyclic communication
transmission mode in which request PDUs and response PDUs are exchanged repetitively in
the scheduled time slots synchronized with a transmission cycle for the lower layer protocol of
the type 24 fieldbus
Note 1 to entry:  In the AL, the communication cycle arises from the transmission cycle in this mode.
3.2.16
cycle scale counter
counter to generate a communication cycle by means of scaling a primary cycle or a
transmission cycle
3.2.17
device ID
part of “device information” to identify the device for a specific product type or model of the
type 24 fieldbus
3.2.18
device information
formatted and device-embedded information to characterize a device, which mainly consists
of data for device model identification and device-profile specific parameters for the type 24
fieldbus
3.2.19
device profile
collection of device model-common information and functionality providing consistency
between different device models among the same kind of devices
3.2.20
dual transfer
transfer mode for the FDC protocol of the type 24 FAL, in which a sender sends a same PDU
twice a transaction and a receiver uses them to detect and recover a communication error
such as data-corruption or data-loss in cyclic communication mode
3.2.21
event driven communication
transmission mode for the lower layer protocol of the type 24 fieldbus in which a transaction
of command-response-exchanging arises as user’s demands
Note 1 to entry:  Both the transmission cycle and the communication cycle don’t arise in this mode.
3.2.22
error
abnormal condition or malfunction for communication or any other activities
3.2.23
field device control service
FDC service
time-critical communication service that handles a fixed length command data to control a
field device and the corresponding feedback response data in a severe restriction on delay or
jitter for the communication timing for the type 24 FAL
3.2.24
field device control protocol
time-critical communication protocol that handles a fixed length command data to control a
field device and the corresponding feedback response data in a severe restriction on delay or
jitter for the communication timing for the type 24 FAL
3.2.25
master
class or its instance object of FDC application service element (ASE) who plays a role of a
command requester for the type 24 FAL
3.2.26
message service
MSG service
communication service that handles the variable length data and not required a severe
restriction on response time
– 14 – IEC 61158-5-24:2014 © IEC 2014
3.2.27
monitor
class or its instance object of FDC ASE who plays a role of a watcher or subscriber of
commands and response between other communication nodes for the type 24 FAL
3.2.28
monitor slave
variant of slave AP type who has both slave class and monitor class for FDC ASE of the
type 24 FAL
3.2.29
network clock
synchronized and periodically running counter that each nodes in a same network have, which
becomes an oscillation source of the transmission cycle
3.2.30
protocol machine
state machine that realizes the protocol as the main function of the entity in each layer
3.2.31
requester
class or its instance object of MSG ASE who plays a role of a command requester or sender
for the type 24 FAL
3.2.32
responder
class or its instance object of MSG ASE who plays a role of a command responder or receiver
for the type 24 FAL
3.2.33
response
PDU issued by a responder or a slave to inform a result or some status for the received
command to a requester or a master
3.2.34
service
operation or process that an object performs upon request from another object
3.2.35
single transfer
normal transfer mode for the FDC protocol of the type 24 FAL in which a sender sends a
same PDU once a transaction
3.2.36
slave AP
AP type that has slave facilities for the FDC service of the type 24 FAL, or the device
implementing that AP type
3.2.37
Slave
FDC slave
class or its instance object of FDC ASE who plays a role of a responder for the type 24 FAL
3.2.38
state machine
logical automatic machine or automaton that has a finite number of states and handles state
transition fired by an event as a trigger

3.2.39
sync command
type of command or APDU of the FDC service of the type 24 FAL, which is issued at the
synchronized timing with every communication cycle
Note 1 to entry:  Definitions which command should be sync one or not are dependent on an application. They may
be provided as a registered set of commands and responses or a device profiles (see IEC 61158-6-24, 4.4 and
Annex A).
3.2.40
synchronous communication
state or a way of communication for the FDC service of the type 24 FAL, in which a command
is issued at the synchronized timing with every communication cycle
Note 1 to entry:  In this state, both sync commands and async ones can be issued.
Note 2 to entry:  In this state, an out-of-synchronization error of APs shall be detected by measures of the
watchdog counter.
3.2.41
transmission cycle
period of repetitive activities for the lower layers of the type 24 fieldbus, which of all the slave
devices are synchronized with that of a C1 master device by the lower layer protocol
3.2.42
transmission mode
state or a way of transmission for the lower layer protocol of the type 24 fieldbus; cyclic mode,
event driven mode
3.2.43
virtual memory space
large data block of APOs for the type 24 FAL which can be read and write with pseudo-
memory-addresses to provide consistency between different device models
Note 1 to entry:  The virtual memory space includes the device information and other vender specific area. See
IEC 61158-6-24, Annex B.
3.2.44
warning
field device status to tell that the device has detected a slight or passing problem but still
working normally through the field device control (FDC) service of the type 24 fieldbus
Note 1 to entry:  Any warning statuses are latched and need to be operated to clear them.
Note 2 to entry:  Warnings are classified into three groups, communication warnings, illegal-command-related
ones, and application specific ones. But concrete definitions are dependent on implementation of each field
devices.
3.3 Abbreviations and symbols
For the purposes of this document, the following abbreviations and symbols apply.
AE Application Entity
AL Application Layer
A-, AL- Application layer (as a prefix)
AP Application Process
APDU Application Protocol Data Unit
API Application Process Invocation
APO Appl
...