IEC 61499-1:2005

Function blocks - Part 1: Architecture

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.

General Information

• Status: Published
• Publication Date: 23-Jan-2005
• ICS: 25.040.40 - Industrial process measurement and control
• ICS: 35.240.50 - IT applications in industry
• Technical Committee: SC 65B - Measurement and control devices
• Drafting Committee: WG 15 - TC 65/SC 65B/WG 15
• Current Stage: DELPUB - Deleted Publication
• Start Date: 07-Nov-2012
• Completion Date: 26-Oct-2025

Relations

• Replaces: IEC PAS 61499-1:2000 - Function blocks for industrial-process measurement and control systems - Part 1: Architecture
• Effective Date: 05-Sep-2023
• Revised: IEC 61499-1:2012 - Function blocks - Part 1: Architecture
• Effective Date: 05-Sep-2023

Overview

IEC 61499-1:2005 - Function blocks: Part 1: Architecture defines a generic, implementation-oriented architecture for using function blocks in distributed Industrial-Process Measurement and Control Systems (IPMCSs). The standard presents implementable reference models, textual syntax and graphical representations to support modular, reusable and distributed control applications. It is intended to guide designers, vendors and integrators in building portable, event-driven function block networks for industrial automation.

Key topics and technical requirements

• Reference models: system, device, resource, application, function block, distribution and management models that form the architectural foundation.
• Function block types: specifications for basic, composite function blocks, subapplications and adapter interfaces.
• Execution model: event-driven behavior for basic function blocks, including Execution Control Charts (ECCs) and timing semantics for deterministic execution.
• Communication and service interfaces: definitions for communication function blocks, service interface function blocks, and management function blocks that support distributed services and lifecycle control.
• Configuration rules: principles for configuring resources, devices, network segments and complete systems; type specifications for resources and devices.
• Operational state & management models: state machines and management primitives for coordinated control, fault handling and deployment.
• Syntax and models: textual syntax, object models, annexes (including relationship to IEC 61131-3) and examples to support implementation and tool development.

Applications and who uses it

IEC 61499 is used where modular, distributed and portable control is required:

• Control system architects and automation engineers designing distributed control systems (DCS) and industrial IoT solutions.
• System integrators and OEMs implementing reusable libraries of function blocks across devices and vendors.
• Software tool vendors building engineering environments, code generators and runtime platforms that support function block networks.
• Researchers and organizations migrating from IEC 61131-3 to component-based, event-driven control paradigms.

Practical use cases include distributed process control, modular machine control, factory automation with edge devices, and systems requiring deterministic, event-driven coordination across networked resources.

Related standards

• IEC 61131-3 - programming languages and PLC semantics (relationship discussed in Annex D).
• Other IEC publications (catalogue references) that govern numbering, editions and normative references for correct application.

IEC 61499 keywords: function blocks, distributed control, IPMCS, execution model, ECC, adapter interfaces, service interface, configuration, modular automation, industrial standard.

Standards Content (Sample)

INTERNATIONAL IEC
STANDARD 61499-1
First edition
2005-01
Function blocks –
Part 1:
Architecture
Reference number
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INTERNATIONAL IEC
STANDARD 61499-1
First edition
2005-01
Function blocks –
Part 1:
Architecture
 IEC 2005  Copyright - all rights reserved
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– 2 – 61499-1 ¤ IEC:2005(E)
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 .20
4.4 Application model .21
4.5 Function block model.22
4.5.1 Characteristics of function block instances .22
4.5.2 Function block type specifications .23
4.5.3 Execution model for basic function blocks .24
4.6 Distribution model .26
4.7 Management model .26
4.8 Operational state models.28
5 Specification of function block, subapplication and adapter interface types.28
5.1 Overview.28
5.2 Basic function blocks.29
5.2.1 Type declaration .29
5.2.2 Behavior of instances.32
5.3 Composite function blocks .34
5.3.1 Type specification.34
5.3.2 Behavior of instances.36
5.4 Subapplications.37
5.4.1 Type specification.37
5.4.2 Behavior of instances.38
5.5 Adapter interfaces .39
5.5.1 General principles.39
5.5.2 Type specification.40
5.5.3 Usage.40
5.6 Exception and fault handling.43
6 Service interface function blocks .43
6.1 General principles .43
6.1.1 General .43
6.1.2 Type specification.44
6.1.3 Behavior of instances.45
6.2 Communication function blocks.47
6.2.1 Type specification.47
6.2.2 Behavior of instances.48
6.3 Management function blocks .49
6.3.1 Requirements .49
6.3.2 Type specification.49
6.3.3 Behavior of managed function blocks .52

61499-1¤ IEC:2005(E) – 3 –
7 Configuration of functional units and systems .55
7.1 Principles of configuration .55
7.2 Functional specification of resource and device types .55
7.2.1 Functional specification of resource types .55
7.2.2 Functional specification of device types.56
7.3 Configuration requirements.56
7.3.1 Configuration of systems.56
7.3.2 Specification of applications.56
7.3.3 Configuration of devices and resources.57
7.3.4 Configuration of network segments and links.58
Annex A (normative) Event function blocks .59
Annex B (normative) Textual syntax.66
Annex C (informative) Object models .77
Annex D (informative) Relationship to IEC 61131-3 .84
Annex E (informative) Information exchange .87
Annex F (normative/informative) Textual specifications .95
Annex G (informative) Attributes .108
Figure 1 – System model .19
Figure 2 – Device model (example: Device 2 from Figure 1) .20
Figure 3 – Resource model.21
Figure 4 – Application model.22
Figure 5 – Characteristics of function blocks .23
Figure 6 – Execution model .25
Figure 7 – Execution timing .25
Figure 8 – Distribution and management models .27
Figure 9 – Function block and subapplication types.29
Figure 10 – Basic function block type declaration .30
Figure 11 – ECC example .32
Figure 12 – ECC operation state machine .33
Figure 13 – Composite function block PI_REAL example .35
Figure 14 – Basic function block PID_CALC example .36
Figure 15 – Subapplication PI_REAL_APPL example .38
Figure 16 – Adapter interfaces – Conceptual model .39
Figure 17 – Adapter type declaration – graphical example.40
Figure 18 – Illustration of provider and acceptor function block type declarations .42
Figure 19 – Illustration of adapter connections .43
Figure 20 – Example service interface function blocks.45
Figure 21 – Examples of time-sequence diagrams.46
Figure 22 – Generic management function block type.49
Figure 23 – Service primitive sequences for unsuccessful service .50
Figure 24 – Operational state machine of a managed function block.54

– 4 – 61499-1  IEC:2005(E)
Figure A.1 – Event split and merge .65
Figure C.1 – ESS overview .77
Figure C.2 – Library elements.78
Figure C.3 – Declarations .79
Figure C.4 – Function block network declarations.80
Figure C.5 – Function block type declarations .81
Figure C.6 – IPMCS overview .81
Figure C.7 – Function block types and instances.83
Figure D.1 – Example of a “simple” function block type .84
Figure E.1 – Type specifications for unidirectional transactions .88
Figure E.2 – Connection establishment for unidirectional transactions .88
Figure E.3 – Normal unidirectional data transfer.88
Figure E.4 – Connection release in unidirectional data transfer .89
Figure E.5 – Type specifications for bidirectional transactions .89
Figure E.6 – Connection establishment for bidirectional transaction.90
Figure E.7 – Bidirectional data transfer .90
Figure E.8 – Connection release in bidirectional data transfer .90

Table 1 – States and transitions of ECC operation state machine .33
Table 2 – Standard inputs and outputs for service interface function blocks.44
Table 3 – Service primitive semantics .47
Table 4 – Variable semantics for communication function blocks .48
Table 5 – Service primitive semantics for communication function blocks .48
Table 6 – CMD input values and semantics .50
Table 7 – STATUS output values and semantics .50
Table 8 – Command syntax.51
Table 9 – Semantics of actions in Figure 24 .54
Table A.1 – Event function blocks .59
Table C.1 – ESS class descriptions .78
Table C.2 – Syntactic productions for library elements .78
Table C.3 – Syntactic productions for declarations .79
Table C.4 – IPMCS classes .82
Table D.1 – Semantics of STATUS values.85
Table E.1 – COMPACT encoding of fixed length data types.94
Table G.1 – Elements of attribute definitions .109

61499-1¤ IEC:2005(E) – 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
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
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6) All users should ensure that they have the latest edition of this publication.
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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 IEC technical committee 65:
Industrial-process measurement and control.
This standard cancels and replaces IEC/PAS 61499-1 published in 2000. This first edition
constitutes a technical revision.
The following major technical changes have occurred between the PAS edition and this
edition:
a) Syntax for network segments, links and parameters has been added in Clause B.3 to
correspond to the system model of 4.1.
b) Syntax for parameters instead of constant data connections has been included for
parameterization of function blocks, devices and resources in Clauses B.2 and B.3 for
better consistency with IEC 61131-3.
c) The execution control model of 5.2.2.2 has been simplified and updated for consistency
with modern models of state machine control.

– 6 – 61499-1 ¤ IEC:2005(E)
The text of this standard is based on the following documents:
CDV Report on voting
65/338/CDV 65/346/RVC
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.
IEC 61499 consists of the following parts, under the general title Function blocks:
Part 1: Architecture
Part 2: Software tool requirements
Part 3: Tutorial information
Part 4: Rules for compliance profiles
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result 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.
A bilingual version of this standard may be issued at a later date.
___________
Under consideration.
61499-1¤ IEC:2005(E) – 7 –
INTRODUCTION
The IEC 61499 series consists of four Parts:
d) Part 1 (this part of IEC 61499) 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.
e) Part 2 defines requirements for software tools to support the following systems
engineering tasks enumerated in Clause 1 of this part of IEC 61499:
• 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.
f) Part 3 has the purpose of increasing the understanding, acceptance, and both generic
and domain-specific applicability of IPMCS architectures and software tools meeting the
requirements of the other Parts, by providing:
• answers to Frequently Asked Questions (FAQs) regarding the IEC 61499 series;
• examples of the use of IEC 61499 constructs to solve frequently encountered
problems in control and automation engineering.
g) 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:2005(E)
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.
NOTE 1 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 part of IEC 61499 may be restricted by the functional capabilities
of compliant systems, subsystems, and devices.
Part of the purpose of this part of IEC 61499 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 part of IEC 61499 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 part of IEC 61499 be concise, implementable, complete, unambiguous, and
consistent.
NOTE 2 The provisions of this part of IEC 61499 alone are not sufficient to ensure interoperability among devices
of different vendors. Standards complying with this part of IEC 61499 may specify additional provisions to ensure
such interoperability.
NOTE 3 Standards complying with this part of IEC 61499 may specify additional provisions to enable the
performance of system, device, resource and application management functions.
2 Normative references
The following referenced documents are indispensable for the application 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.
IEC 60050-351:1998, International Electrotechnical Vocabulary (IEV) – Part 351: Automatic
Control
IEC 61131-3:2003, Programmable controllers – Part 3: Programming languages
ISO/IEC 7498-1:1994, Information Technology – Open Systems Interconnection – Basic
Reference Model: The Basic Model
ISO/IEC 8824-1, Information technology - Abstract Syntax Notation One (ASN.1):
Specification of basic notation)

61499-1¤ IEC:2005(E) – 9 –
ISO/IEC 8825-1, Information technology - ASN.1 encoding rules: Specification of Basic
Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules
(DER)
ISO/IEC 10646, Information technology - Universal Multiple-Octet Coded Character Set
(UCS)
ISO/IEC 10731, Information technology - Open Systems Interconnection - Basic Reference
Model - Conventions for the definition of OSI services
ISO/AFNOR, Dictionary of Computer Science, 1989, ISBN 2-12-4869111-6
3 Terms and definitions
For the purposes of this document, the terms and definitions given in the ISO/AFNOR
Dictionary of computer science, as well as the following apply.
NOTE Terms defined in this clause are italicized where they appear in the bodies of definitions.
3.1
acceptor
function block instance which provides a socket adapter of a defined adapter interface type
3.2
access path
association of a symbolic name with a variable for the purpose of open communication
3.3
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
3.4
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
3.5
algorithm
finite set of well-defined rules for the solution of a problem in a finite number of operations
3.6
application
software functional unit that is specific to the solution of a problem in industrial-process
measurement and control
NOTE An application may be distributed among resources, and may communicate with other applications.
3.7
attribute
property or characteristic of an entity, for instance, the version identifier of a function block
type specification
3.8
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

– 10 – 61499-1 ¤ IEC:2005(E)
3.9
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
3.10
character
member of a set of elements that is used for the representation, organization, or control of
data
[ISO/AFNOR: 1989]
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 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 (of a programmable controller system)
language element corresponding to a programmable controller system as defined in
IEC 61131-1
61499-1¤ IEC:2005(E) – 11 –
3.20
configuration parameter
parameter related to the configuration of a system, device or resource
3.21
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
3.22
connection
association established between functional units for conveying information
[ISO/AFNOR: 1989]
3.23
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
3.24
data
reinterpretable representation of information in a formalized manner suitable for
communication, interpretation or processing
[ISO 2382-01.01.02]
3.25
data connection
association between two function blocks for the conveyance of data
3.26
data input
interface of a function block which receives data from a data connection
3.27
data output
interface of a function block which supplies data to a data connection
3.28
data type
set of values together with a set of permitted operations
[ISO 2382-15.04.01]
3.29
declaration
mechanism for establishing the definition of an entity
NOTE A declaration may involve attaching an identifier to the entity, and allocating attributes such as data types
and algorithms to it.
3.30
device
independent physical entity capable of performing one or more specified functions in a
particular context and delimited by its interfaces
NOTE A programmable controller system as defined in IEC 61131-1 is a device.

– 12 – 61499-1 ¤ IEC:2005(E)
3.31
device management application
application whose primary function is the management of a multiple resources within a device
3.32
entity
particular thing, such as a person, place, process, object, concept, association, or event
3.33
event
instantaneous occurrence that is significant to scheduling the execution of an algorithm
NOTE The execution of an algorithm may make use of variables associated with an event.
3.34
event connection
association among function blocks for the conveyance of events
3.35
event input
interface of a function block which can receive events from an event connection
3.36
event output
interface of a function block which can issue events to an event connection
3.37
exception
event that causes suspension of normal execution
3.38
execution
process of carrying out a sequence of operations specified by an algorithm
NOTE 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.
3.39
Execution Control action
EC action
element associated with an execution control state, which identifies an algorithm to be
executed and an event to be issued on completion of execution of the algorithm
3.40
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
3.41
Execution Control initial state
EC initial state
execution control state that is active upon initialization of an execution control chart

61499-1¤ IEC:2005(E) – 13 –
3.42
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
3.43
Execution Control transition
EC transition
means by which control passes from a predecessor execution control state to a successor
execution control state
3.44
fault
abnormal condition that may cause a reduction in, or loss of, the capability of a functional unit
to perform a required function
[IEC 61508-4:1998, 3.6.1]
3.45
function
specific purpose of an entity or its characteristic action
3.46
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 Typical operations of a function block include modification of the values of the data in its associated data
structure.
NOTE 2 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.
3.47
function block network
network whose nodes are function blocks or subapplications and their parameters and whose
branches are data connections and event connections
NOTE This is a generalization of the function block diagram defined in IEC 61131-3.
3.48
function block type
type whose instances are function blocks
NOTE Function block types include basic function block types, composite function block types, and service
interface function block types
3.49
functional unit
entity of hardware or software, or both, capable of accomplishing a specified purpose
[ISO 2382-01.01.40]
3.50
hardware
physical equipment, as opposed to programs, procedures, rules and associated
documentation
[ISO/AFNOR: 1989]
– 14 – 61499-1 ¤ IEC:2005(E)
3.51
identifier
one or more characters used to name an entity
3.52
implementation
development phase in which the hardware and software of a system become operational
3.53
indication primitive
service primitive which represents an interaction in which a resource either: a) indicates that
it has, on its own initiative, invoked some algorithm; or b) indicates that an algorithm has
been invoked by a peer application
3.54
information
meaning that is currently assigned to data by means of the conventions applied to that data
[ISO/AFNOR: 1989]
3.55
input variable
variable whose value is supplied by a data input, and which may be used in one or more
operations of a function block
NOTE An input parameter of a function block, as defined in IEC 61131-3, is an input variable.
3.56
instance
functional unit comprising an individual, named entity with the attributes of a defined type
3.57
instance name
identifier associated with and designating an instance
3.58
instantiation
creation of an instance of a specified type
3.59
interface
shared boundary between two functional units, defined by functional characteristics, signal
characteristics, or other characteristics as appropriate
[IEV 351-11-19]
3.60
internal operation (of a function block)
operation associated with an algorithm of a function block, with its execution control, or with
the functional capabilities of the associated resource
3.61
internal variable
variable whose value is used or modified by one or more operations of a function block but is
not supplied by a data input or to a data output

61499-1¤ IEC:2005(E) – 15 –
3.62
invocation
process of initiating the execution of the sequence of operations specified in an algorithm
3.63
link
design element describing the connection between a device and a network segment
3.64
literal
lexical unit that directly represents a value
3.65
management function block
function block whose primary function is the management of applications within a resource
3.66
management resource
resource whose primary function is the management of other resources
3.67
mapping
set of features or attributes having defined correspondence with the members of another set
3.68
message
ordered series of characters intended to convey information
[ISO 2382-16.02.01]
3.69
message sink
part of a communication system in which messages are considered to be received
[ISO 2382-16.02.03)
3.70
message source
part of a communication system from which messages are considered to originate
[ISO 2382-16.02.02]
3.71
model
representation of a real world process, device, or concept
3.72
multitasking
mode of operation that provides for the concurrent execution of two or more algorithms
3.73
network
arrangement of nodes and interconnecting branches
[ISO 2382-01.01.44]
– 16 – 61499-1 ¤ IEC:2005(E)
3.74
operation
well-defined action that, when applied to any permissible combination of known entities,
produces a new entity
[ISO 2382-02.10.01]
3.75
output variable
variable whose value is established by one or more operations of a function block, and is
supplied to a data output
NOTE An output parameter of a function block, as defined in IEC 61131-3, is an output variable.
3.76
parameter
variable that is given a constant value for a specified application and that may denote the
application
[ISO 2382-02.02.04]
3.77
plug
plug adapter
instance of an adapter interface type which provides a starting point for an adapter
connection from a provider function block
3.78
provider
function block instance which provides a plug adapter of a defined adapter interface type
3.79
request primitive
service primitive which represents an interaction in which an application invokes some
algorithm provided by a service
3.80
requester
functional unit which initiates a transaction via a request primitive
3.81
resource
functional unit which has independent control of its operation, and which provides various
services to applications, including the scheduling and execution of algorithms
NOTE 1 The RESOURCE defined in IEC 61131-3 is a programming language element corresponding to the
resource defined above.
NOTE 2 A device contains one or more resources.
3.82
resource management application
application whose primary function is the management of a single resource
3.83
responder
functional unit which concludes a transaction via a response primitive

61499-1¤ IEC:2005(E) – 17 –
3.84
response primitive
service primitive which represents an interaction in which an application indicates that it has
completed some algorithm previously invoked by an interaction represented by an indication
primitive
3.85
sample
sense and retain the instantaneous value of a variable for later use
3.86
scheduling function
function which selects algorithms or operations for execution, and initiates and terminates
this execution
3.87
segment
physical partition of a communication network
3.88
service
functional capability of a resource which can be modeled by a sequence of service primitives
3.89
service interface function block
function block which provides one or more services to an application, based on a mapping of
service primitives to the function block's event inputs, event outputs, data inputs and data
outputs
3.90
service primitive
abstract, implementation-independent representation of an interaction between an application
and a resource
3.91
socket
socket adapter
instance of an adapter interface type which provides an end point for an adapter connection
to an acceptor function block
3.92
software
intellectual creation comprising the programs, procedures, rules, configurations and any
associated documentation pertaining to the operation of a system
3.93
software tool
software that is used for the production, inspection or analysis of other software
3.94
subapplication instance
instance of a subapplication type inside an application or inside a subapplication type
NOTE A subapplication instance may be distributed among resources, i.e. its component function blocks or the
content of its component subapplications may be assigned to different resources.

– 18 – 61499-1 ¤ IEC:2005(E)
3.95
subapplication type
functional unit whose body consists of interconnected component function blocks or
component subapplications
NOTE A subapplication type enables the creation of substructures of applications in the form of a self-similar
hierarchy.
3.96
system
set of interrelated elements considered in a defined context as a whole and separated from
its environment
[IEV-351-11-01]
NOTE 1 Such elements may be both material objects and concepts as well as the results thereof (for example
forms of organisation, mathematical methods, and programming languages)
NOTE 2 The system is considered to be separated from the environment and other external systems by an
imaginary surface, which can cut the links between them and the considered system.
3.97
transaction
unit of service in which a request and possibly data is conveyed from a requester to a
responder, and in which a response and possibly data may also be conveyed from the
responder back to the requester
3.98
type
software element which specifies the common attributes shared by all instances of the type
3.99
type name
identifier associated with and designating a type
3.100
unidirectional transaction
transaction in which a request and possibly data is conveyed from an requester to a
responder, and in which a response is not conveyed from the responder back to the
requester
3.101
variable
software entity that may take different values, one at a time
NOTE 1 The values of a variable are usually restricted to a certain data type.
NOTE 2 Variables may be classified as input variables, output variables, and
...