IEC PAS 61499-1:2000

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Edition 1.0
2000-09
Function blocks for industrial-process
measurement and control systems
Part 1: Architecture
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IN TER N A TION A L Reference number
E L E C TROTE CHNI CA L
IEC/PAS 61499-1
C O MMI S S I O N
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
FUNCTION BLOCKS FOR INDUSTRIAL-PROCESS MEASUREMENT

AND CONTROL SYSTEMS –
Part 1: Architecture
FOREWORD
A PAS is a technical specification not fulfilling the requirements for a standard, but made available to the
public and established in an organization operating under given procedures.
IEC-PAS 61499-1 has been processed by IEC technical committee 65: Industrial-process measurement and
control.
The text of this PAS is based on the This PAS was approved for
following document: publication by the P-members of the
committee concerned as indicated in
the following document:
Draft PAS Report on voting
65/248/PAS 65/252/RVD
Following publication of this PAS, the technical committee or subcommittee concerned will investigate the
possibility of transforming the PAS into an International Standard.
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising all
national electrotechnical committees (IEC National Committees). The object of the 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, the IEC publishes International Standards. 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. The 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 the 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
National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form of
standards, technical reports or guides and they are accepted by the National Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International Standards
transparently to the maximum extent possible in their national and regional standards. Any divergence between the
IEC Standard and the corresponding national or regional standard shall be clearly indicated in the latter.

5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this PAS may be the subject of patent rights. The
IEC shall not be held responsible for identifying any or all such patent rights.

TABLE OF CONTENTS
1. GENERAL REQUIREMENTS. 7
1.1. Scope. 7
1.2. Normative references. 8
1.3. Definitions . 8

1.3.1. Definitions from other standards . 8

1.3.2. Additional definitions . 9

1.4. Reference models. 14

1.4.1. System model . 14

1.4.2. Device model . 14

1.4.3. Resource model. 15
1.4.4. Application model. 16
1.4.5. Function block model . 17
1.4.5.1. Characteristics of function block instances. 17
1.4.5.2. Function block type specifications.18
1.4.5.3. Execution model for basic function blocks. 19
1.4.6. Distribution model . 21
1.4.7. Management model . 21
1.4.8. Operational state models . 22
2. FUNCTION BLOCK AND SUBAPPLICATION TYPE SPECIFICATION . 24
2.1. Overview . 24
2.2. Basic function blocks. 26
2.2.1. Type declaration. 26
2.2.1.1. Event interface declaration. 26
2.2.1.2. Algorithm declaration . 27
2.2.1.3. Declaration of algorithm execution control. 27
2.2.2. Behavior of instances. 28
2.2.2.1. Initialization. 28
2.2.2.2. Algorithm invocation. 28
2.2.2.3. Algorithm execution. 31
2.3. Composite function blocks . 31
2.3.1. Type specification . 31
2.3.2. Behavior of instances. 34
2.4. Subapplications. 34
2.4.1. Type specification . 34
2.4.2. Behavior of instances. 36
2.5. Adapter interfaces . 37
2.5.1. Type specification . 37
2.5.2. Usage. 38
2.6. Exception and fault handling . 40
3. SERVICE INTERFACE FUNCTION BLOCKS. 41
3.1. General principles . 41
3.1.1. Type specification . 41
3.1.2. Behavior of instances. 43
3.2. Communication function blocks .45
3.2.1. Type specification . 45
3.2.2. Behavior of instances. 45
3.3. Management function blocks . 46
3.3.1. Requirements. 46
3.3.2. Type specification . 46
3.3.3. Behavior of managed function blocks . 50
4. CONFIGURATION OF FUNCTIONAL UNITS AND SYSTEMS . 54
4.1. Functional specification of types . 54
4.1.1. Functional specification of resource types . 54

4 Copyright © 2000, IEC
4.1.2. Functional specification of device types. 55

4.2. Configuration requirements. 55

4.2.1. Configuration of systems. 55

4.2.2. Specification of applications. 55

4.2.3. Configuration of devices and resources. 55

5. COMPLIANCE . 57

5.1. Compliant systems and subsystems. 57

5.2. Compliant devices. 57
5.3. Compliant standards . 59

ANNEX A - EVENT FUNCTION BLOCKS (normative). 60

ANNEX B - TEXTUAL SYNTAX (normative) . 68
B.1. Syntax specification technique. 68
B.1.1. Syntax. 68
B.1.1.1. Terminal symbols. 68
B.1.1.2. Non-terminal symbols. 68
B.1.1.3. Production rules. 68
B.1.2. Semantics . 69
B.2. Function block and subapplication type specification . 70
B.2.1 Function block type specification . 70
B.2.2 Subapplication type specification. 73
B.3. Configuration elements. 74
B.4. Common elements . 77
B.5. Supporting productions for management commands. 77
B.6. Tagged data types . 77
B.7. Adapter interface types. 77
ANNEX C - OBJECT MODELS (informative) . 78
C.1. ESS Models. 78
C.1.1 Library elements . 79
C.1.2 Declarations. 80
C.1.3. Function block network declarations . 82
C.1.4. Function block type declarations .82
C.2. IPMCS models. 83
ANNEX D - RELATIONSHIP TO IEC 61131-3(informative) . 87
D.1. Simple function blocks. 87
D.2. Event-driven functions and function blocks . 88
ANNEX E - COMMON ELEMENTS (normative). 89
E.1 Compliance requirement. 89
E.2. Exceptions . 89

E.3 Extensions . 89
ANNEX F - INFORMATION EXCHANGE (informative). 90
F.1. Use of application layer facilities. 90
F.2. Communication function block types . 90
F.2.1. Function blocks for unidirectional transactions . 91
F.2.2. Function blocks for bidirectional transactions . 92
F.3. Transfer syntaxes . 94
F.3.1. Abstract syntaxes. 94
F.3.1.1. IEC61499-FBDATA. 94
F.3.1.2. IEC61499-FBMGT . 96
F.3.2. Encoding rules . 99
F.3.2.1. BASIC encoding. 99
F.3.2.2. COMPACT encoding . 99

ANNEX G - DEVICE AND RESOURCE MANAGEMENT (informative) . 102

G.1. Device management . 102

G.2. Resource management. 102

G.3. Applications of management function blocks. 102

G.3.1. Device management . 102

G.3.2. Resource management. 103

ANNEX H - TEXTUAL SPECIFICATIONS (normative/informative). 104

ANNEX I - IMPLEMENTATION CONSIDERATIONS (informative). 122

ANNEX J - ATTRIBUTES (informative) . 123

J.1. General principles . 123
J.2. Attribute definitions. 123
J.3. Examples. 124
J.4. Attribute sources . 125
J.5. Attribute inheritance . 125
J.6 Declaration syntax. 125
LIST OF TABLES
Table 2.2.2.2-1 - States and transitions of event input state machine . 29
Table 2.2.2.2-2 - States and transitions of ECC operation state machine. 30
Table 3.1.1 - Standard inputs and outputs for service interface function blocks . 41
Table 3.1.2 - Service primitive semantics . 44
Table 3.2.1 - Variable semantics for communication function blocks. 45
Table 3.2.2 - Service primitive semantics for communication function blocks. 46
Table 3.3.2-1 - CMD input values and semantics. 48
Table 3.3.2-2 - STATUS output values and semantics . 48
Table 3.3.2-3 - Command syntax. 49
Table 3.3.3 - Substates, transitions and actions of Figure 3.3.3-2. 53
Table 5.2 - Device compliance classes. 58
Table A.1 - Event function blocks. 61
Table C.1 - ESS Class descriptions. 79
Table C.1.1 - Syntactic productions for library elements. 80
Table C.1.2 - Syntactic productions for declarations. 82
Table C.2-1 - IPMCS classes. 85
Table D.1 - Semantics of STATUS values. 88
Table F.3.1.2 - Use of IEC61499-FBMGT types . 96

Table F.3.2.2 - COMPACT encoding of fixed length data types . 100
Table J.2 - Elements of attribute definitions. 124
LIST OF FIGURES
Figure 1.4.1 - System model. 14
Figure 1.4.2 - Device model (example: Device 2 from figure 1.4.1) . 15
Figure 1.4.3 - Resource model. 16
Figure 1.4.4 - Application model . 17
Figure 1.4.5.1 - Characteristics of function blocks. 18
Figure 1.4.5.3-1 - Execution model. 20

6 Copyright © 2000, IEC
Figure 1.4.5.3-2 - Execution timing . 20

Figure 1.4.7 - Management models -a) Shared, b) Distributed. 22

Figure 2.1 - Function block and subapplication types . 25

Figure 2.2.1 - Basic function block type declaration. 26

Figure 2.2.1.3 - ECC example. 28

Figure 2.2.2.2-1 - Event input state machine . 29

Figure 2.2.2.2-2 - ECC operation state machine. 30

Figure 2.3.1-1 - Composite function block PI_REAL example . 33

Figure 2.3.1-2 - Basic function block PID_CALC example. 34

Figure 2.4.1 - Subapplication PI_REAL_APPL example . 36
Figure 2.5 - Adapter interfaces - Conceptual model . 37
Figure 2.5.1 - Adapter type declaration - graphical example . 38
Figure 2.5.2-1 - Illustration of provider and acceptor function block type declarations . 39
Figure 2.5.2-2 - Illustration of adapter connections. 40
Figure 3.1.1 - Example service interface function blocks:. 43
Figure 3.1.2 - Example time-sequence diagrams . 44
Figure 3.3.2-1 - Generic management function block type. 47
Figure 3.3.2-2 - Service primitive sequences for unsuccessful service . 47
Figure 3.3.3-1 - Operational state machine of a managed function block . 52
Figure 3.3.3-2 - RUNNING state for composite function blocks . 53
Figure A.1 - Event split and merge. 67
Figure C.1 - ESS Overview . 78
Figure C.1.1 - Library elements. 79
Figure C.1.2 - Declarations . 81
Figure C.1.3 - Function block network declarations. 82
Figure C.1.4 - Function block type declarations. 83
Figure C.2-1 - IPMCS overview. 84
Figure C.2-2 - Function block types and instances. 86
Figure D.1 - Example of a simple function block type. 87
Figure F.2.1-1 - Type specifications for unidirectional transactions. 91
Figure F.2.1-2- Connection establishment for unidirectional transactions . 91
Figure F.2.1-3 - Normal unidirectional data transfer . 91
Figure F.2.1-4- Connection release in unidirectional data transfer . 92
Figure F.2.2-1 - Type specifications for bidirectional transactions. 92
Figure F.2.2-2 - Connection establishment for bidirectional transaction. 93

Figure F.2.2-3 - Bidirectional data transfer. 93
Figure F.2.2-4 - Connection release in bidirectional data transfer . 93
Figure G.3.1 - Remote device management application. 103

1. GENERAL REQUIREMENTS
1.1. Scope
This Specification 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 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 - This Specification 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. Clause 5 of this Part addresses the extent to
which the elements defined in this Specification may be restricted by the functional capabilities of compliant systems,
subsystems, and devices.
Part of the purpose of this specification 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
Specification 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 Specification be concise,
implementable, complete, unambiguous, and consistent.
NOTE 1 The provisions of this Specification alone are not sufficient to ensure interoperability among devices
of different vendors. Standards complying with this Specification may specify additional provisions to
ensure such interoperability.
NOTE 2 Standards complying with this Specification may specify additional provisions to enable the
performance of system, device, resource and application management functions.
This Specification consists of two Parts:
- Part 1, "Architecture", contains:
- general requirements, including an introduction, 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 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;
- requirements to be met by compliant systems and standards.
- Part 2, "Engineering task support", will present guidance for the support of engineering
tasks in the design, implementation, operation and maintenance of distributed industrial-
process measurement and control systems constructed according to the architecture
defined in this Part.
8 Copyright © 2000, IEC
1.2. Normative references
The following normative documents contain provisions which, through reference in this text,

constitute provisions of this specification. At the time of publication, the editions indicated were
valid. All normative documents are subject to revision, and parties to agreements based on this
specification are encouraged to investigate the possibility of applying the most recent editions of

the normative documents indicated below. Members of the IEC and ISO maintain registers of

currently valid International Standards.

IEC 600050-351(1998?), International Electrotechnical Vocabulary Chapter 351: Automatic
Control (2nd.Ed.)
IEC 559 (1989), Binary floating-point arithmetic for microprocessors

IEC 617-12 (1983), Graphical symbols for diagrams, Part 12: Binary logic elements
IEC 65B/373/CD, Committee Draft - IEC 61131-3, Programmable controllers, Part 3:
Programming languages, 2nd Ed., 1998-11-27.
ISO 2382 (various Parts and dates), Information processing systems - Vocabulary
ISO 8601:1988, Data elements and interchange formats - Information interchange -
Reresentations of dates and times
ISO/AFNOR, Dictionary of Computer Science, 1989, ISBN 2-12-4869111-6
ISO/IEC 7498-1, Information Technology - Open Systems Interconnection - Basic Reference
Model, 1994
ISO/IEC 8824: 1990, Information technology - Open Systems Interconnection - Specification
of Abstract Syntax Notation One (ASN.1)
ISO/IEC 8825: 1990, Information technology - Open Systems Interconnection - Specification
of Basic Encoding Rules for Abstract Syntax Notation One (ASN.1)
ISO TR 8509-1987, Information processing systems - Open Systems Interconnection -
Service conventions
ISO/IEC 10040-1992, Information technology - Open Systems Interconnection - Systems
management overview
ISO/IEC 10646-1:1993, Information technology - Universal multiple-octet coded Character Set
(UCS) - Part 1: Architecture and Basic Multilingual Plane
1.3. Definitions
NOTE 1 - Terms defined in this clause are italicized where they appear in the bodies of definitions.
NOTE 2 - The ISO/AFNOR Dictionary of computer science and the International Electrotechnical Vocabulary
should be consulted for terms not defined or referenced in this specification.
1.3.1. Definitions from other standards

NOTE Definitions are written out in this document for convenience. To avoid duplication, the terms alone will
be listed in the final International Standard.
For the purposes of this specification, the following terms as defined in IEC 60050-351 apply:
interface: A shared boundary between two functional units, defined by functional
characteristics, signal characteristics, or other characteristics as appropriate.
system: A set of interrelated elements considered in a defined context as a whole and
separated from its environment.
Notes: 1 -Such elements may be both material objects and concepts as well as the results thereof (e.g.
forms of organisation, mathematical methods, and programming languages)
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.
For the purposes of this specification, the following terms as defined in the various Parts of ISO
2382 apply:
NOTE - Definition numbers from ISO 2382 are given in parentheses following the definition.

data type: A set of values together with a set of permitted operations. (15.04.01)

data: A reinterpretable representation of information in a formalized manner suitable

for communication, interpretation or processing. (01.01.02)

functional unit: An entity of hardware or software, or both, capable of accomplishing

a specified purpose. (01.01.40)

mapping: A set of values having defined correspondence with the quantities or values

of another set. (02.04.05)
message: An ordered series of characters intended to convey information. (16.02.01)

message sink: That part of a communication system in which messages are

considered to be received. (16.02.03)
message source: That part of a communication system from which messages are
considered to originate. (16.02.02)
network: An arrangement of nodes and interconnecting branches. (01.01.44)
operation: A well-defined action that, when applied to any permissible combination of
known entities, produces a new entity. (02.10.01)
parameter: A variable that is given a constant value for a specified application and that
may denote the application. (02.02.04)
For the purposes of this specification, the following terms as defined in the ISO/AFNOR Dictionary
of Computer Science apply:
character: A member of a set of elements that is used for the representation,
organization, or control of data.
connection: An association established between functional units for conveying
information.
hardware: Physical equipment, as opposed to programs, procedures, rules and
associated documentation.
information: The meaning that is currently assigned to data by means of the
conventions applied to that data.
For the purposes of this specification, the following term as defined in the document IEC DIS
61508-4: Functional safety - Safety-related systems - Part 4: Definitions and Abbreviations of
Terms applies:
fault: abnormal condition that may cause a reduction in, or loss of, the capability of a
functional unit to perform a required function.
1.3.2. Additional definitions
The following terms are defined for the purposes of this specification.
1.3.2.1. acceptor: A function block instance which provides a socket adapter of a defined
adapter interface type.
1.3.2.2. access path: The association of a symbolic name with a variable for the purpose of
open communication.
1.3.2.3. adapter connection: A 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.
1.3.2.4. adapter interface type: A 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.
1.3.2.5. algorithm: A finite set of well-defined rules for the solution of a problem in a finite
number of operations.
10 Copyright © 2000, IEC
1.3.2.6. application: A 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.

1.3.2.7. attribute: a property or characteristic of an entity, for instance, the version identifier of

a function block type specification.

1.3.2.8. basic function block type: a function block type which cannot be decomposed into

other function blocks and which utilizes an execution control chart (ECC) to control the

execution of its algorithms.
1.3.2.9. bidirectional transaction: A 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
1.3.2.10. communication connection: A connection which utilizes the "communication
mapping function" of one or more resources for the conveyance of information.
1.3.2.11. communication function block: A service interface function block which represents
the interface between an application and the "communication mapping function" of a
resource.
1.3.2.12. communication function block type: A function block type whose instances are
communication function blocks.
1.3.2.13. component function block: A 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.
1.3.2.14. component subapplication: A subapplication instance which is used in the
specification of a subapplication type.
1.3.2.15. composite function block type: A function block type whose algorithms and the
control of their execution are expressed entirely in terms of interconnected component
function blocks, events, and variables.
1.3.2.16. concurrent: Pertaining to algorithms that are executed during a common period of
time during which they may have to alternately share common resources.
1.3.2.17. configuration (of a system or device) : A step in system design: selecting functional
units, assigning their locations and defining their interconnections.
1.3.2.18. configuration (of a programmable controller system) : A language element
corresponding to a programmable controller system as defined in IEC 61131-1.
1.3.2.19. configuration parameter: A parameter related to the configuration of a system,
device or resource.
1.3.2.20. confirm primitive: A 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.
1.3.2.21. critical region: An operation or a 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.
1.3.2.22. data connection: An association between two function blocks for the conveyance of
data.
1.3.2.23. data input: An interface of a function block which receives data from a data
connection.
1.3.2.24. data output: An interface of a function block which supplies data to a data connection.

1.3.2.25 declaration: The mechanism for establishing the definition of an entity. A declaration

may involve attaching an identifier to the entity, and allocating attributes such as data

types and algorithms to it.
1.3.2.26. device: An 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 in the terms of this
Specification.
1.3.2.27. device management application: An application whose primary function is the

management of a multiple resources within a device.

1.3.2.28. entity: A particular thing, such as a person, place, process, object, concept,

association, or event.
1.3.2.29. event: An 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.
1.3.2.30. event connection: An association among function blocks for the conveyance of
events.
1.3.2.31. event input: An interface of a function block which receives events from an event
connection.
1.3.2.32. event input variable (EI variable): A Boolean variable corresponding to an event
input.
1.3.2.33. event output: An interface of a function block which issues events to an event
connection.
1.3.2.34. event output variable (EO variable): A Boolean variable corresponding to an event
output.
1.3.2.35. exception: An event that causes suspension of normal execution.
1.3.2.36. execution: The 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.
1.3.2.37. execution control action (EC action): An 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.
1.3.2.38. execution control chart (ECC): A 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.
1.3.2.39. execution control initial state (EC initial state): The execution control state which is
active upon initialization of an execution control chart.
1.3.2.40. execution control state (EC state): A situation in which the behavior of a basic
function block with respect to its variables is determined by the algorithms associated
with the execution control state through its execution control action.
1.3.2.41. execution control transition (EC transition): The condition whereby control passes
from a predecessor execution control state to a successor execution control state.
1.3.2.42. function: A specific purpose of an entity or its characteristic action.
1.3.2.43. function block (function block instance): A software functional unit comprising an
individual, named copy of a data structure and associated operations specified by a
corresponding function block type.

12 Copyright © 2000, IEC
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.

1.3.2.44. function block network: A network whose nodes are function blocks or

subapplications and their parameters and whose branches are data connections and

event
...