SIST EN 61499-1:2013

SLOVENSKI STANDARD
01-april-2013
1DGRPHãþD
SIST EN 61499-1:2006
Funkcijski bloki - 1. del: Arhitektura (IEC 61499-1:2012)
Function blocks - Part 1: Architecture (IEC 61499-1:2012)
Funktionsbausteine für industrielle Leitsysteme - Teil 1: Architektur (IEC 61499-1:2012)
Blocs fonctionnels - Partie 1: Architecture (CEI 61499-1:2012)
Ta slovenski standard je istoveten z: EN 61499-1:2013
ICS:
25.040.40 Merjenje in krmiljenje Industrial process
industrijskih postopkov measurement and control
35.240.50 Uporabniške rešitve IT v IT applications in industry
industriji
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 61499-1
NORME EUROPÉENNE
February 2013
EUROPÄISCHE NORM
ICS 25.040; 35.240.50 Supersedes EN 61499-1:2005

English version
Function blocks -
Part 1: Architecture
(IEC 61499-1:2012)
Blocs fonctionnels -  Funktionsbausteine für industrielle
Partie 1: Architecture Leitsysteme -
(CEI 61499-1:2012) Teil 1: Architektur
(IEC 61499-1:2012)
This European Standard was approved by CENELEC on 2012-12-12. CENELEC members are bound to comply
with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the CEN-CENELEC Management Centre or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and notified
to the CEN-CENELEC Management Centre has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus,
the Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany,
Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Management Centre: Avenue Marnix 17, B - 1000 Brussels

© 2013 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61499-1:2013 E
Foreword
The text of document 65B/845/FDIS, future edition 2 of IEC 61499-1, prepared by SC 65B
"Measurement and control devices" of IEC/TC 65 "Industrial-process measurement, control and
automation" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
The following dates are fixed:
• latest date by which the document has (dop) 2013-09-12
to be implemented at national level by
publication of an identical national
standard or by endorsement
(dow) 2015-12-12
• latest date by which the national
standards conflicting with the
document have to be withdrawn
This document supersedes EN 61499-1:2005.

EN 61499-1:2005:
• Execution control in basic function blocks (5.2) has been clarified and extended:
- dynamic and static parts of the EC transition condition are clearly delineated by using the
ec_transition_event[guard_condition] syntax of the Unified Modeling Language (UML) (5.2.1.3,
B.2.1);
- the terminology "crossing of an EC transition" (3.10) is used preferentially to "clearing" to avoid
the misinterpretation that the entire transition condition corresponds to a Boolean variable that
can be "cleared.";
- operation of the ECC state machine in 5.2.2.2 has been clarified and made more rigorous;
- event and data outputs of adapter instances (plugs and sockets) can be used in EC transition
conditions, and event inputs of adapter instances can be used as EC action outputs.
• Temporary variables (3.97) can be declared (B.2.1) and used in algorithms of basic function blocks.
• Service sequences (6.1.3) can now be defined for basic and composite function block types and
adapter types, as well as service interface types.
• The syntax for mapping of FB instances from applications to resources has been simplified
(Clause B.3).
• Syntax for definition of segment types (7.2.3) for network segments of system configurations has
been added (Clause B.3).
• Function block types for interoperation with programmable controllers are defined (Clause D.6).
• The READ/WRITE management commands (Table 8) now apply only to parameters.

Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such
patent rights.
- 3 - EN 61499-1:2013
Endorsement notice
The text of the International Standard IEC 61499-1:2012 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:

IEC 61131-5:2000 NOTE Harmonised as EN 61131-5:2001 (not modified).
IEC 61499 Series NOTE Harmonised as EN 61499 Series (not modified).
IEC 61499-2:2012 NOTE Harmonised as EN 61499-2:2013 (not modified).
IEC 61499-4 NOTE Harmonised as EN 61499-4.

Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

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  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.
Publication Year Title EN/HD Year

IEC 61131-1 - Programmable controllers - EN 61131-1 -
Part 1: General information
IEC 61131-3 2003 Programmable controllers - EN 61131-3 2003
Part 3: Programming languages
ISO/IEC 7498-1 1994 Information technology - Open Systems - -
Interconnection - Basic Reference Model:
The Basic Model
ISO/IEC 8824-1 2008 Information technology - Abstract Syntax - -
Notation One (ASN.1): Specification of basic
notation
ISO/IEC 10646 2003 Information technology - Universal multiple- - -
octet coded character set (UCS)

IEC 61499-1 ®
Edition 2.0 2012-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Function blocks –
Part 1: Architecture
Blocs fonctionnels –
Partie 1: Architecture
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XF
ICS 25.040; 35.240.50 ISBN 978-2-83220-481-8

– 2 – 61499-1 © IEC:2012
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 Reference models . 18
4.1 System model. 18
4.2 Device model . 19
4.3 Resource model . 19
4.4 Application model . 21
4.5 Function block model. 21
4.5.1 Characteristics of function block instances . 21
4.5.2 Function block type specifications . 23
4.5.3 Execution model for basic function blocks . 23
4.6 Distribution model . 25
4.7 Management model . 25
4.8 Operational state models . 27
Specification of function block, subapplication and adapter interface types . 27
5.1 Overview . 27
5.2 Basic function blocks . 28
5.2.1 Type declaration . 28
5.2.2 Behavior of instances . 30
5.3 Composite function blocks . 33
5.3.1 Type specification . 33
5.3.2 Behavior of instances . 35
5.4 Subapplications . 36
5.4.1 Type specification . 36
5.4.2 Behavior of instances . 37
5.5 Adapter interfaces . 38
5.5.1 General principles . 38
5.5.2 Type specification . 38
5.5.3 Usage . 39
5.6 Exception and fault handling. 41
Service interface function blocks . 41
6.1 General principles . 41
6.1.1 General . 41
6.1.2 Type specification . 42
6.1.3 Behavior of instances . 43
6.2 Communication function blocks . 45
6.2.1 Type specification . 45
6.2.2 Behavior of instances . 46
6.3 Management function blocks . 47
6.3.1 Requirements . 47
6.3.2 Type specification . 47
6.3.3 Behavior of managed function blocks. 50
7 Configuration of functional units and systems . 52

61499-1 © IEC:2012 – 3 –
7.1 Principles of configuration . 52
7.2 Functional specification of resource, device and segment types . 52
7.2.1 Functional specification of resource types . 52
7.2.2 Functional specification of device types . 53
7.2.3 Functional specification of segment types . 53
7.3 Configuration requirements . 53
7.3.1 Configuration of systems . 53
7.3.2 Specification of applications . 54
7.3.3 Configuration of devices and resources . 54
7.3.4 Configuration of network segments and links . 55
Annex A (normative) Event function blocks . 56
Annex B (normative) Textual syntax . 63
Annex C (informative) Object models . 74
Annex D (informative) Relationship to IEC 61131-3 . 82
Annex E (informative) Information exchange . 92
Annex F (normative) Textual specifications . 100
Annex G (informative) Attributes . 113
Bibliography . 117

Figure 1 – System model . 18
Figure 2 – Device model . 19
Figure 3 – Resource model . 20
Figure 4 – Application model . 21
Figure 5 – Characteristics of function blocks . 22
Figure 6 – Execution model . 24
Figure 7 – Execution timing . 24
Figure 8 – Distribution and management models . 26
Figure 9 – Function block and subapplication types . 28
Figure 10 – Basic function block type declaration . 29
Figure 11 – ECC example . 30
Figure 12 – ECC operation state machine . 32
Figure 13 – Composite function block PI_REAL example . 34
Figure 14 – Basic function block PID_CALC example . 35
Figure 15 – Subapplication PI_REAL_APPL example . 37
Figure 16 – Adapter interfaces – Conceptual model . 38
Figure 17 – Adapter type declaration – graphical example . 39
Figure 18 – Illustration of provider and acceptor function block type declarations. 40
Figure 19 – Illustration of adapter connections . 41
Figure 20 – Example service interface function blocks . 43
Figure 21 – Example service sequence diagrams . 44
Figure 22 – Generic management function block type . 47
Figure 23 – Service primitive sequences for unsuccessful service . 48
Figure 24 – Operational state machine of a managed function block . 51
Figure A.1 – Event split and merge . 62

– 4 – 61499-1 © IEC:2012
Figure C.1 – ESS overview . 74
Figure C.2 – Library elements . 75
Figure C.3 – Declarations . 76
Figure C.4 – Function block network declarations . 77
Figure C.5 – Function block type declarations . 79
Figure C.6 – IPMCS overview . 79
Figure C.7 – Function block types and instances . 81
Figure D.1 – Example of a “simple” function block type . 82
Figure D.2 – Function block type READ . 85
Figure D.3 – Function block type UREAD . 87
Figure D.4 – Function block type WRITE . 88
Figure D.5 – Function block type TASK . 90
Figure E.1 – Type specifications for unidirectional transactions . 93
Figure E.2 – Connection establishment for unidirectional transactions . 93
Figure E.3 – Normal unidirectional data transfer . 93
Figure E.4 – Connection release in unidirectional data transfer . 94
Figure E.5 – Type specifications for bidirectional transactions . 94
Figure E.6 – Connection establishment for bidirectional transaction . 95
Figure E.7 – Bidirectional data transfer . 95
Figure E.8 – Connection release in bidirectional data transfer . 95

Table 1 – States and transitions of ECC operation state machine . 32
Table 2 – Standard inputs and outputs for service interface function blocks . 42
Table 3 – Service primitive semantics . 45
Table 4 – Variable semantics for communication function blocks . 46
Table 5 – Service primitive semantics for communication function blocks . 46
Table 6 – CMD input values and semantics . 48
Table 7 – STATUS output values and semantics . 48
Table 8 – Command syntax . 49
Table 9 – Semantics of actions in Figure 24 . 52
Table A.1 – Event function blocks . 57
Table C.1 – ESS class descriptions . 75
Table C.2 – Syntactic productions for library elements . 75
Table C.3 – Syntactic productions for declarations . 77
Table C.4 – IPMCS classes . 80
Table D.1 – Semantics of STATUS values . 83
Table D.2 – Source code of function block type READ . 86
Table D.3 – Source code of function block type UREAD . 87
Table D.4 – Source code of function block type WRITE . 89
Table D.5 – Source code of function block type TASK . 90
Table D.6 – IEC 61499 interoperability features . 91
Table E.1 – COMPACT encoding of fixed length data types . 99
Table G.1 – Elements of attribute definitions . 114

61499-1 © IEC:2012 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FUNCTION BLOCKS –
Part 1: Architecture
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,
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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.
International Standard IEC 61499-1 has been prepared by subcommittee 65B: Measurement
and control devices, of IEC technical committee 65: Industrial-process measurement, control
and automation.
This second edition cancels and replaces the first edition published in 2005. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
• Execution control in basic function blocks (5.2) has been clarified and extended:
– Dynamic and static parts of the EC transition condition are clearly delineated by using
the ec_transition_event[guard_condition] syntax of the Unified Modeling
Language (UML) (5.2.1.3, B.2.1).
– The terminology "crossing of an EC transition" (3.10) is used preferentially to "clearing"
to avoid the misinterpretation that the entire transition condition corresponds to a
Boolean variable that can be "cleared."

– 6 – 61499-1 © IEC:2012
– Operation of the ECC state machine in 5.2.2.2 has been clarified and made more
rigorous.
– Event and data outputs of adapter instances (plugs and sockets) can be used in EC
transition conditions, and event inputs of adapter instances can be used as EC action
outputs.
• Temporary variables (3.97) can be declared (B.2.1) and used in algorithms of basic
function blocks.
• Service sequences (6.1.3) can now be defined for basic and composite function block
types and adapter types, as well as service interface types.
• The syntax for mapping of FB instances from applications to resources has been simplified
(Clause B.3).
• Syntax for definition of segment types (7.2.3) for network segments of system
configurations has been added (Clause B.3).
• Function block types for interoperation with programmable controllers are defined
(Clause D.6).
• The READ/WRITE management commands (Table 8) now apply only to parameters.
The text of this part of IEC 61499 is based on the following documents:
FDIS Report on voting
65B/845/FDIS 65B/855/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 (when voting is completed).
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the IEC 61499 series can be found, under the general title Function
blocks, on the IEC website.
Terms used throughout this International Standard that have been defined in Clause 3 appear
in italics.
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.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
61499-1 © IEC:2012 – 7 –
INTRODUCTION
IEC 61499 consists of the following parts, under the general title Function blocks:
• Part 1 (this document) contains:
– general requirements, including scope, normative references, definitions, and
reference models;
– rules for the declaration of function block types, and rules for the behavior of instances
of the types so declared;
– rules for the use of function blocks in the configuration of distributed industrial-process
measurement and control systems (IPMCSs);
– rules for the use of function blocks in meeting the communication requirements of
distributed IPMCSs;
– rules for the use of function blocks in the management of applications, resources and
devices in distributed IPMCSs.
• Part 2 defines requirements for software tools to support the following systems
engineering tasks:
– the specification of function block types;
– the functional specification of resource types and device types;
– the specification, analysis, and validation of distributed IPMCSs;
– the configuration, implementation, operation, and maintenance of distributed IPMCSs;
– the exchange of information among software tools.
• Part 3 (Tutorial information) has been withdrawn due to the widespread current availability
nd
of tutorial and educational materials regarding IEC 61499. However, an updated 2
Edition of Part 3 may be developed in the future.
• Part 4 defines rules for the development of compliance profiles which specify the features
of IEC 61499-1 and IEC 61499-2 to be implemented in order to promote the following
attributes of IEC 61499-based systems, devices and software tools:
– interoperability of devices from multiple suppliers;
– portability of software between software tools of multiple suppliers; and
– configurability of devices from multiple vendors by software tools of multiple suppliers.

– 8 – 61499-1 © IEC:2012
FUNCTION BLOCKS –
Part 1: Architecture
1 Scope
This part of IEC 61499 defines a generic architecture and presents guidelines for the use of
function blocks in distributed industrial-process measurement and control systems (IPMCSs).
This architecture is presented in terms of implementable reference models, textual syntax and
graphical representations. These models, representations and syntax can be used for:
• the specification and standardization of function block types;
• the functional specification and standardization of system elements;
• the implementation independent specification, analysis, and validation of distributed
IPMCSs;
• the configuration, implementation, operation, and maintenance of distributed IPMCSs;
• the exchange of information among software tools for the performance of the above
functions.
This part of IEC 61499 does not restrict or specify the functional capabilities of IPMCSs or
their system elements, except as such capabilities are represented using the elements
defined herein. IEC 61499-4 addresses the extent to which the elements defined in this
standard may be restricted by the functional capabilities of compliant systems, subsystems,
and devices.
Part of the purpose of this standard is to provide reference models for the use of function
blocks in other standards dealing with the support of the system life cycle, including system
planning, design, implementation, validation, operation and maintenance. The models given in
this standard are intended to be generic, domain independent and extensible to the definition
and use of function blocks in other standards or for particular applications or application
domains. It is intended that specifications written according to the rules given in this standard
be concise, implementable, complete, unambiguous, and consistent.
NOTE 1 The provisions of this standard alone are not sufficient to ensure interoperability among devices of
different vendors. Standards complying with this part of IEC 61499 can specify additional provisions to ensure such
interoperability.
NOTE 2 Standards complying with this part of IEC 61499 can specify additional provisions to enable the
performance of system, device, resource and application management functions.
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.
IEC 61131-1, Programmable controllers – Part 1: General
IEC 61131-3:2003, Programmable controllers – Part 3: Programming languages
IEC/ISO 7498-1:1994, Information technology – Open systems interconnection – Basic
reference model: The basic model

61499-1 © IEC:2012 – 9 –
ISO/IEC 8824-1:2008, Information technology – Abstract Syntax Notation One (ASN.1):
Specification of basic notation
ISO/IEC 10646:2003, Information technology – Universal Multiple-Octet Coded Character
Set (UCS)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
NOTE Terms defined in Clause 3 are italicized where they appear in definitions and Notes to entry of other terms
as well as throughout the body of the document.
3.1
acceptor
function block instance which provides a socket adapter of a defined adapter interface type
3.2
adapter connection
connection from a plug adapter to a socket adapter of the same adapter interface type, which
carries the flows of data and events defined by the adapter interface type
3.3
adapter interface type
type which consists of the definition of a set of event inputs, event outputs, data inputs, and
data outputs, and whose instances are plug adapters and socket adapters
3.4
algorithm
finite set of well-defined rules for the solution of a problem in a finite number of operations
3.5
application
software functional unit that is specific to the solution of a problem in industrial-process
measurement and control
Note 1 to entry: An application can be distributed among resources, and might communicate with other
applications.
3.6
attribute
property or characteristic of an entity, for instance, the version identifier of a function block
type specification
3.7
basic function block type
function block type that cannot be decomposed into other function blocks and that utilizes an
execution control chart (ECC) to control the execution of its algorithms
3.8
bidirectional transaction
transaction in which a request and possibly data are conveyed from an requester to a
responder, and in which a response and possibly data are conveyed from the responder back
to the requester
– 10 – 61499-1 © IEC:2012
3.9
character
member of a set of elements that is used for the representation, organization, or control of
data
3.10
crossing
clearing
operation by means of which control is passed from the predecessor EC
state of an EC transition to its successor EC state
Note 1 to entry: This operation consists of de-activation of the predecessor EC state, followed by activation of the
successor EC state.
3.11
communication connection
connection that utilizes the communication mapping function of one or more resources for the
conveyance of information
3.12
communication function block
service interface function block that represents the interface between an application and the
communication mapping function of a resource
3.13
communication function block type
function block type whose instances are communication function blocks
3.14
component function block
function block instance which is used in the specification of an algorithm of a composite
function block type
Note 1 to entry: A component function block can be of basic, composite or service interface type.
3.15
component subapplication
subapplication instance that is used in the specification of a subapplication type
3.16
composite function block type
function block type whose algorithms and the control of their execution are expressed entirely
in terms of interconnected component function blocks, events, and variables
3.17
concurrent
pertaining to algorithms that are executed during a common period of time during which they
may have to alternately share common resources
3.18
configuration (of a system or device)
selecting functional units, assigning their locations and defining their interconnections
3.19
configuration parameter
parameter related to the configuration of a system, device or resource

61499-1 © IEC:2012 – 11 –
3.20
confirm primitive
service primitive which represents an interaction in which a resource indicates completion of
some algorithm previously invoked by an interaction represented by a request primitive
3.21
connection
association established between functional units for conveying information
3.22
critical region
operation or sequence of operations which is executed under the exclusive control of a
locking object which is associated with the data on which the operations are performed
3.23
data
reinterpretable representation of information in a formalized manner suitable for
communication, interpretation or processing
3.24
data connection
association between two function blocks for the conveyance of data
3.25
data input
interface of a function block which receives data from a data connection
3.26
data output
interface of a function block which supplies data to a data connection
3.27
data type
set of values together with a set of permitted operations
3.28
declaration
mechanism for establishing the definition of an entity
Note 1 to entry: A declaration can involve attaching an identifier to the entity, and allocating attributes such as
data types and algorithms to it.
3.29
device
independent physical entity capable of performing one or more specified functions in a
particular context and delimited by its interfaces
Note 1 to entry: A programmable controller system as defined in IEC 61131-1 is a device.
3.30
device management application
application whose primary function is the management of multiple resources within a device
3.31
entity
particular thing, such as a person, place, process, object, concept, association, or event

– 12 – 61499-1 © IEC:2012
3.32
event
instantaneous occurrence that is significant to scheduling the execution of an algorithm
Note 1 to entry: The execution of an algorithm may make use of variables associated with an event.
3.33
event connection
association among function blocks for the conveyance of events
3.34
event input
interface of a function block which can receive events from an event connection
3.35
event output
interface of a function block which can issue events to an event connection
3.36
exception
event that causes suspension of normal execution
3.37
execution
process of carrying out a sequence of operations specified by an algorithm
Note 1 to entry: The sequence of operations to be executed may vary from one invocation of a function block
instance to another, depending on the rules specified by the function block's algorithm and the current values of
variables in the function block's data structure.
3.38
execution control action
EC action
element associated with an execution control state, which identifies an algorithm to be
executed, an event to be issued, or both
Note 1 to entry: Timing of algorithm execution and event issuance are addressed in 5.2.2.
3.39
execution control chart
ECC
graphical or textual representation of the causal relationships among events at the event
inputs and event outputs of a function block and the execution of the function block's
algorithms, using execution control states, execution control transitions, and execution control
actions
3.40
execution control initial state
EC initial state
execution control state that is active upon initialization of an execution control chart
3.41
execution control state
EC state
situation in which the behavior of a basic function block with respect to its variables is
determined by the algorithms associated with a specified set of execution control actions

61499-1 © IEC:2012 – 13 –
3.42
execution control transition
EC transition
means by which control passes from a predecessor execution control state to a successor
execution control state
3.43
fault
abnormal condition that may cause a reduction in, or loss of, the capability of a functional unit
to perform a required function
3.44
function
specific purpose of an entity or its characteristic action
3.45
function block
function block instance
software functional unit comprising an individual, named copy of a data structure upon which
associated operations may be performed as specified by a corresponding function block type
Note 1 to entry: Typical operations of a function block include modification of the values of the data in its
associated data structure.
Note 2 to entry: The function block instance and its corresponding function block type defined in IEC 61131-3 are
programming language elements with a different set of features.
3.46
function block network
network whose nodes are function blocks or subapplications and their parameters and whose
branches are data connections and event connections
Note 1 to entry: This is a generalization of the function block diagram defined in IEC 61131-3.
3.47
function block type
type whose instances are function blocks
Note 1 to entry: Function block types include basic function block types, composite function block types, and
service interface function block types
3.48
functional unit
entity
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