SIST EN 61804-2:2007

Function blocks (FB) for process control -- Part 2: Specification of FB concept

This part of IEC 61804 is applicable to Function Blocks (FB) for process control. This standard specifies FB by using the result of harmonization work as regards several elements: c) the device model which defines the components of an IEC 61804-2 conformant device; d) conceptual specifications of FBs for measurement, actuation and processing. This includes general rules for the essential features to support control, whilst avoiding details which stop innovation as well as specialization for different industrial sectors. This standard defines a subset of the requirements of IEC 61804-1 (hereafter referred to as Part 1) only, while Part 1 describes requirements for a distributed system. The conformance statement in Annex B, which covers the conformance declaration, is related to this standard only. Requirements of Part 1 are not part of these conformance declarations. The standardization work for FB was carried out by harmonizing the description of concepts of existing technologies. It results in an abstract level that allowed the definition of the common features in a unique way. This abstract vision is called here the conceptual FB specification and mapped to specific communication systems and their accompanying definitions by the industrial groups. This standard is also based on the abstract definitions of IEC 61499-1.

Funktionsbausteine für die Prozessautomation -- Teil 2: Festlegung des Funktionsbausteinkonzepts

Blocs fonction pour les processus industriels -- Partie 2: Spécification du concept de bloc fonction

Is applicable to Function Blocks (FB) for process control and specifies the Electronic Device Description Language (EDDL), specifies FB by using the result of harmonization work as regards several elements. defines a subset of the requirements of EN 61804-1 (hereafter referred to as Part 1) only, while Part 1 describes requirements for a distributed system.

Funkcijski bloki (FB) za nadzor procesov - 2. del: Specifikacije koncepta FB (IEC 61804-2:2006)

General Information

• Status: Withdrawn
• Publication Date: 21-Oct-2007
• Withdrawal Date: 20-Dec-2020
• ICS: 25.040.40 - Industrial process measurement and control
• ICS: 35.060 - Languages used in information technology
• ICS: 35.240.50 - IT applications in industry
• Technical Committee: MOV - Measuring equipment for electromagnetic quantities
• Current Stage: 9900 - Withdrawal (Adopted Project)
• Start Date: 21-Dec-2020
• Due Date: 13-Jan-2021
• Completion Date: 21-Dec-2020
• Ref Project: EN 61804-2:2007 - Function blocks (FB) for process control - Part 2: Specification of FB concept

Relations

• Replaces: SIST EN 61804-2:2004 - Function Blocks (FB) for process control -- Part 2: Specification of FB concept and Electronic Device Description Language (EDDL)
• Effective Date: 01-May-2010
• Replaced By: SIST EN IEC 61804-2:2018 - Function blocks (FB) for process control and electronic device description language (EDDL) - Part 2: Specification of FB concept (IEC 61804-2:2018)
• Effective Date: 07-Jun-2022
• Revised: SIST EN 61804-2:2004 - Function Blocks (FB) for process control -- Part 2: Specification of FB concept and Electronic Device Description Language (EDDL)
• Effective Date: 13-May-2010
• Replaced By: SIST EN IEC 61804-2:2018 - Function blocks (FB) for process control and electronic device description language (EDDL) - Part 2: Specification of FB concept (IEC 61804-2:2018)
• Effective Date: 10-Sep-2013
• Replaces: SIST EN 61804-2:2004 - Function Blocks (FB) for process control -- Part 2: Specification of FB concept and Electronic Device Description Language (EDDL)
• Effective Date: 28-Jan-2023
• Replaced By: SIST EN IEC 61804-2:2018 - Function blocks (FB) for process control and electronic device description language (EDDL) - Part 2: Specification of FB concept (IEC 61804-2:2018)
• Effective Date: 28-Jan-2023

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 61804-2:2007
01-december-2007
Nadomešča:
SIST EN 61804-2:2004

Funkcijski bloki (FB) za nadzor procesov - 2. del: Specifikacije koncepta FB (IEC

61804-2:2006)
Function blocks (FB) for process control -- Part 2: Specification of FB concept
Funktionsbausteine für die Prozessautomation -- Teil 2: Festlegung des
Funktionsbausteinkonzepts

Blocs fonction pour les processus industriels -- Partie 2: Spécification du concept de bloc

fonction
Ta slovenski standard je istoveten z: EN 61804-2:2007
ICS:
25.040.40 Merjenje in krmiljenje Industrial process
industrijskih postopkov measurement and control
35.060 Jeziki, ki se uporabljajo v Languages used in
informacijski tehniki in information technology
tehnologiji
35.240.50 Uporabniške rešitve IT v IT applications in industry
industriji
SIST EN 61804-2:2007 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN 61804-2:2007
---------------------- Page: 2 ----------------------
SIST EN 61804-2:2007
EUROPEAN STANDARD
EN 61804-2
NORME EUROPÉENNE
June 2007
EUROPÄISCHE NORM
ICS 25.040.40; 35.240.50 Partially supersedes EN 61804-2:2004
English version
Function blocks (FB) for process control -
Part 2: Specification of FB concept
(IEC 61804-2:2006)
Blocs fonction Funktionsbausteine
pour les processus industriels - für die Prozessautomation -
Partie 2: Spécification du concept Teil 2: Festlegung
de bloc fonction des Funktionsbausteinkonzepts
(IEC 61804-2:2006)
(CEI 61804-2:2006)

This European Standard was approved by CENELEC on 2007-05-01. 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 Central Secretariat 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 Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Cyprus, the

Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,

Sweden, Switzerland and the United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2007 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 61804-2:2007 E
---------------------- Page: 3 ----------------------
SIST EN 61804-2:2007
EN 61804-2:2007 - 2 -
Foreword

The text of the International Standard IEC 61804-2:2006, prepared by SC 65C, Industrial networks, of

IEC TC 65, Industrial-process measurement and control, was submitted to the formal vote and was

approved by CENELEC as EN 61804-2 on 2007-05-01 without any modification.

This European Standard, together with EN 61804-3:2007, supersedes EN 61804-2:2004.

EN 61804-2:2007 includes the following significant technical changes with respect to EN 61804-2:2004:

– transfer of the EDDL-specific clauses to EN 61804-3;

– the FB-specific subclauses 4.1 and 4.2 as well as Clauses 5, 6, 7 and 8 are unchanged.

The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2008-05-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2010-05-01

The International Electrotechnical Commission (IEC) and CENELEC draw attention to the fact that it is

claimed that compliance with this document may involve the use of patents
U.S. Patent No. 5,333,114
U.S. Patent No. 5,485,400
U.S. Patent No. 5,825,664
U.S. Patent No. 5,909,368
U.S. Patent Pending No. 08/916,178
Australian Patent No. 638507
Canadian Patent No. 2,066,743
European Patent No. 0495001
Validated in:
UK – Patent No. 0495001
France – Patent No. 0495001
Germany – Patent No. 69032954.7
Netherlands – Patent No. 0495001
Japan Patent No. 3137643

The IEC and CENELEC take no position concerning the evidence, validity and scope of this patent right.

The holder of this patent right has assured the IEC that he is willing to negotiate licenses under

reasonable and non-discriminatory terms and conditions with applicants throughout the world. In this

respect, the statement of the holder of this patent right is registered with IEC. Information may be

obtained from:
Fieldbus Foundation,
9390 Research Boulevard, Suite II-250,
Austin, Texas, USA 78759,
Attention: President.
---------------------- Page: 4 ----------------------
SIST EN 61804-2:2007
- 3 - EN 61804-2:2007

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights other than those identified above. IEC and CENELEC shall not be held responsible for

identifying any or all such patent rights.
Annex ZA has been added by CENELEC.
__________
Endorsement notice

The text of the International Standard IEC 61804-2:2006 was approved by CENELEC as a European

Standard without any modification.
__________
---------------------- Page: 5 ----------------------
SIST EN 61804-2:2007
EN 61804-2:2007 - 4 -
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

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.

NOTE Where an International Publication has been modified by common modifications, indicated by (mod), the relevant EN/HD

applies.
Publication Year Title EN/HD Year
IEC 60050-351 1998 International Electrotechnical Vocabulary - -
(IEV) –
Part 351: Automatic control
1) 2)
IEC 60584-1 - Thermocouples – EN 60584-1 1995
Part 1: Reference tables
IEC 61131-3 2003 Programmable controllers – EN 61131-3 2003
Part 3: Programming languages
IEC 61158 Series Digital data communications for EN 61158 Series
measurement and control - Fieldbus for use
in industrial control systems
IEC 61499-1 2005 Function blocks – EN 61499-1 2005
Part 1: Architecture
IEC 61499-2 2005 Function blocks – EN 61499-2 2005
Part 2: Software tools requirements
IEC/TS 61804-1 2003 Function blocks (FB) for process control – - -
Part 1: Overview of system aspects
ISO/IEC 7498-1 1994 Information technology - Open systems EN ISO/IEC 7498-1 1995
interconnection - Basic reference model –
Part 1: The basic model
ISO/IEC 9899 - Programming languages - C - -
ISO/IEC 10646-1 - Information technology - Universal Multiple-- -
Octet Coded Character Set (UCS) –
Part 1: Architecture and Basic Multilingual
Plane
Undated reference.
Valid edition at date of issue.
---------------------- Page: 6 ----------------------
SIST EN 61804-2:2007
INTERNATIONAL IEC
STANDARD 61804-2
Second edition
2006-09
Function blocks (FB) for process control –
Part 2:
Specification of FB concept
 IEC 2006  Copyright - all rights reserved

No part of this publication may be reproduced or utilized in any form or by any means, electronic or

mechanical, including photocopying and microfilm, without permission in writing from the publisher.

International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland

Telephone: [phone] Telefax: [phone] E-mail: [e-mail] Web: www.iec.ch

PRICE CODE
Commission Electrotechnique Internationale XA
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue
---------------------- Page: 7 ----------------------
SIST EN 61804-2:2007
– 2 – 61804-2  IEC:2006(E)
CONTENTS

FOREWORD...........................................................................................................................4

INTRODUCTION.....................................................................................................................6

1 Scope...............................................................................................................................7

2 Normative references .......................................................................................................7

3 Terms, definitions and abbreviated terms and acronyms...................................................8

3.1 Terms and definitions ..............................................................................................8

3.2 Abbreviated terms and acronyms ..........................................................................14

4 General Function Block (FB) definition and EDD model ..................................................14

4.1 Device structure (device model) ............................................................................14

4.2 Block combinations ...............................................................................................25

5 Detailed block definition .................................................................................................28

5.1 General .................................................................................................................28

5.2 Application FBs .....................................................................................................28

5.3 Component FBs ....................................................................................................36

5.4 Technology Block ..................................................................................................36

5.5 Device (Resource) Block .......................................................................................45

5.6 Algorithms common to all blocks ...........................................................................47

6 FB Environment..............................................................................................................49

7 Mapping to System Management....................................................................................49

8 Mapping to Communication ............................................................................................49

9 Conformance statement..................................................................................................51

Annex A (informative) Parameter description .......................................................................52

Annex B (normative) IEC 61804 Conformance Declaration ..................................................58

Bibliography..........................................................................................................................59

Figure 1 – Position of the IEC 61804 series related to other standards and products ..............6

Figure 2 – FB structure is derived out of the process (P&ID view) .........................................15

Figure 3 – FB structure may be distributed between devices.................................................16

Figure 4 – IEC 61804 FBs can be implemented in different devices ......................................17

Figure 5 – General components of devices ...........................................................................17

Figure 6 – Block types of IEC 61804 .....................................................................................18

Figure 7 – IEC 61804 block overview (graphical representation not normative) .....................19

Figure 8 – UML class diagram of the device model ...............................................................22

Figure 9 – Measurement process signal flow.........................................................................26

Figure 10 – Actuation process signal flow .............................................................................26

Figure 11 – Application process signal flow...........................................................................27

Figure 12 – Analog Input FB .................................................................................................28

Figure 13 – Analog Output FB...............................................................................................30

Figure 14 – Discrete input FB ...............................................................................................31

Figure 15 – Discrete Output FB.............................................................................................32

---------------------- Page: 8 ----------------------
SIST EN 61804-2:2007
61804-2  IEC:2006(E) – 3 –

Figure 16 – Calculation FB....................................................................................................34

Figure 17 – Control FB..........................................................................................................35

Figure 18 – Temperature Technology Block ..........................................................................36

Figure 19 – Pressure Technology Block ................................................................................39

Figure 20 – Modulating actuation technology block ...............................................................41

Figure 21 – On/Off Actuation Technology Block ....................................................................43

Figure 22 – Harel state chart ................................................................................................46

Figure 23 – Application structure of ISO OSI Reference Model .............................................49

Figure 24 – Client/Server relationship in terms of OSI Reference Model ...............................50

Figure 25 – Mapping of IEC 61804 FBs to APOs...................................................................50

Table 1 – References of model elements ..............................................................................21

Table 2 – Variables and parameter description template .......................................................24

Table 3 – Example of temperature sensors of Sensor_Type..................................................37

Table 4 – Device status state table .......................................................................................45

Table 5 – Device status transition table ................................................................................46

Table A.1 – Parameter description ........................................................................................52

Table B.1 – Conformance (sub)clause selection table...........................................................58

Table B.2 – Contents of (sub)clause selection tables ............................................................58

---------------------- Page: 9 ----------------------
SIST EN 61804-2:2007
– 4 – 61804-2  IEC:2006(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
FUNCTION BLOCKS (FB) FOR PROCESS CONTROL –
Part 2: Specification of FB concept
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote

international co-operation on all questions concerning standardization in the electrical and electronic fields. To

this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,

Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC

Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested

in the subject dealt with may participate in this preparatory work. International, governmental and non-

governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely

with the International Organization for Standardization (ISO) in accordance with conditions determined by

agreement between the two organizations.

2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

consensus of opinion on the relevant subjects since each technical committee has representation from all

interested IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

misinterpretation by any end user.

4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

transparently to the maximum extent possible in their national and regional publications. Any divergence

between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in

the latter.

5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any

equipment declared to be in conformity with an IEC Publication.

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.

The International Electrotechnical Commission (IEC) draws attention to the fact that it is claimed that compliance

with this document may involve the use of patents
U.S. Patent No. 5,333,114
U.S. Patent No. 5,485,400
U.S. Patent No. 5,825,664
U.S. Patent No. 5,909,368
U.S. Patent Pending No. 08/916,178
Australian Patent No. 638507
Canadian Patent No. 2,066,743
European Patent No. 0495001
Validated in:
UK – Patent No. 0495001
France – Patent No. 0495001
Germany – Patent No. 69032954.7
Netherlands – Patent No. 0495001
Japan Patent No. 3137643
---------------------- Page: 10 ----------------------
SIST EN 61804-2:2007
61804-2  IEC:2006(E) – 5 –

IEC take no position concerning the evidence, validity and scope of this patent right. The holder of this patent right

has assured the IEC that he is willing to negotiate licenses under reasonable and non-discriminatory terms and

conditions with applicants throughout the world. In this respect, the statement of the holder of this patent right is

registered with IEC. Information may be obtained from:
Fieldbus Foundation,
9390 Research Boulevard, Suite II-250,
Austin, Texas, USA 78759,
Attention: President.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights

other than those identified above. IEC shall not be held responsible for identifying any or all such patent rights.

This International Standard has been prepared by subcommittee 65C: Digital communications,

of IEC technical committee 65: Industrial-process measurement and control.

This second edition, together with the first edition of IEC 61804-3, cancels and replaces the

first edition of IEC 61804-2 published in 2004. This edition constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:
a) transfer of the EDDL-specific clauses to IEC 61804-3;

b) the FB-specific subclauses 4.1 and 4.2 as well as Clauses 5, 6, 7 and 8 are unchanged.

The text of this standard is based on the following documents:
CDV Report on voting
65C/405/CDV 65C/420/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 ISO/IEC Directives, Part 2.

The list of all parts of the IEC 61804 series, under the general title Function Blocks (FB) for

process control, can be found on the IEC website.

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 publication may be issued at a later date.
---------------------- Page: 11 ----------------------
SIST EN 61804-2:2007
– 6 – 61804-2  IEC:2006(E)
INTRODUCTION

This part of IEC 61804 provides conceptual Function Block specifications, which can be

mapped to specific communication systems, and their accompanying definitions by industrial

groups.

The EDDL fills the gap between the conceptual FB specification of IEC 61804-2 and a product

implementation. Figure 1 shows these aspects.
Abstract models IEC 61499-1 ISO 15745-1
Conceptual FB
IEC
IEC 61804 2
specification for
61804 - 3
FB concept
the process
EDDL
sector
IEC/TR
FIP
Controlnet
Solutions FF PROFI-
companion
FB BUS 61804 - 4
(technology)
standards
...
application PA profile
Interoperability
profiles
Guideline
Implementation
Products
IEC 1507/06

Figure 1 – Position of the IEC 61804 series related to other standards and products

---------------------- Page: 12 ----------------------
SIST EN 61804-2:2007
61804-2  IEC:2006(E) – 7 –
FUNCTION BLOCKS (FB) FOR PROCESS CONTROL –
Part 2: Specification of FB concept
1 Scope

This part of IEC 61804 is applicable to Function Blocks (FB) for process control.

This standard specifies FB by using the result of harmonization work as regards several

elements:

c) the device model which defines the components of an IEC 61804-2 conformant device;

d) conceptual specifications of FBs for measurement, actuation and processing. This

includes general rules for the essential features to support control, whilst avoiding details

which stop innovation as well as specialization for different industrial sectors.

This standard defines a subset of the requirements of IEC 61804-1 (hereafter referred to as

Part 1) only, while Part 1 describes requirements for a distributed system.

The conformance statement in Annex B, which covers the conformance declaration, is related

to this standard only. Requirements of Part 1 are not part of these conformance declarations.

The standardization work for FB was carried out by harmonizing the description of concepts of

existing technologies. It results in an abstract level that allowed the definition of the common

features in a unique way. This abstract vision is called here the conceptual FB specification

and mapped to specific communication systems and their accompanying definitions by the

industrial groups. This standard is also based on the abstract definitions of IEC 61499-1.

NOTE This standard can be mapped to ISO 15745-1.

There are solutions on the market today, which fulfil the requirements of this standard and

show how the conceptual specification is implemented in a given technology. New
technologies will need to find equivalent solutions (see Figure 4).
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 60584-1, Thermocouples – Part 1: Reference tables
IEC 61131-3:2003, Programmable controllers – Part 3: Programming languages

IEC 61158 (all parts), Digital data communications for measurement and control – Fieldbus for

use in industrial control systems
IEC 61499-1:2005, Function blocks – Part 1: Architecture
IEC 61499-2:2005, Function blocks – Part 2: Software tools requirements
---------------------- Page: 13 ----------------------
SIST EN 61804-2:2007
– 8 – 61804-2  IEC:2006(E)

IEC 61804-1:2003, Function blocks (FB) for process control − Part 1: Overview of system

aspects

ISO/IEC 7498-1:1994, Information technology – Open Systems Interconnection – Basic

Reference Model: The Basic Model
ISO/IEC 9899, Programming languages − C

ISO/IEC 10646-1, Information technology – Universal Multiple-Octet Coded Character Set

(UCS) – Part 1: Architecture and Basic Multilingual Plane
3 Terms, definitions, and abbreviated terms and acronyms
3.1 Terms and definitions

For the purposes of this document, the following terms and definitions, some of which have

been compiled from the referenced documents, apply.
3.1.1
algorithm

finite set of well-defined rules for the solution of a problem in a finite number of operations

3.1.2
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.

3.1.3
application function block
FB which has no input or output to the process
3.1.4
attribute

property or characteristic of an entity, for instance, the version identifier of an FB type

specification
[IEC 61499-1]

NOTE The formal description of attributes is part of the solution profiles to achieve domain-specific

interoperability. IEC 61804 defines the general rules to define the attributes and specifies the EDDL to describe

attributes, which may be described in solution profiles.
3.1.5
component function block

FB instance which is used in the specification of an algorithm of a composite FB type

NOTE A component FB can be an FB or a composite FB type.
3.1.6
composite FB type

FB type whose algorithm is expressed entirely in terms of interconnected component FBs and

variables
[IEC 61499-1]
---------------------- Page: 14 ----------------------
SIST EN 61804-2:2007
61804-2  IEC:2006(E) – 9 –
3.1.7
configuration (of a system or device)

step in system design: selecting functional units, assigning their locations and defining their

interconnections
[IEC 61499-1]
3.1.8
data

representation of facts, concepts or instructions in a formalized manner suitable for

communication, interpretation or processing by human beings or by automatic means

[ISO/AFNOR Dictionary of Computer Science]
3.1.9
data connection
association established between functional units for conveyance of data
[IEC 61499-1]
3.1.10
data input
interface of an FB which receives data from a data connection
[IEC 61499-1]
3.1.11
data output
interface of an FB, which supplies data to a data connection
[IEC 61499-1]
3.1.12
data type
set of values together with a set of permitted operations
[ISO 2382 series]
3.1.13
device

independent physical entity capable of performing one or more specified functions in a

particular context and delimited by its interfaces
[IEC 61499-1]
3.1.14
device block
FB which has no input and no output
3.1.15
device management application

application whose primary function is the management of a multiple resources within a device

[IEC 61499-1]
3.1.16
Electronic Device Description Language (EDDL)
methodology for describing parameter(s) of an automation system component
---------------------- Page: 15 ----------------------
SIST EN 61804-2:2007
– 10 – 61804-2  IEC:2006(E)
3.1.17
Electronic Device Description (EDD)

data collection containing the device parameter(s), their dependencies, their graphical

representation and a description of the data sets which are transferred.

NOTE The Electronic Device Description is created using the Electronic Device Description Language (EDDL).

3.1.18
entity

particular thing, such as a person, place, process, object, concept, association, or event

[IEC 61499-1]
3.1.19
event

instantaneous occurrence that is significant to scheduling the execution of an algorithm

[IEC 61499-1]

NOTE The execution of an algorithm may make use of variables associated with an event.

3.1.20
exception
event that causes suspension of normal execution
[IEC 61499-1]
3.1.21
function
specific purpose of an entity or its characteristic action
[IEC 61499-1]
3.1.22
functional unit

entity of hardware or software, or both, capable of accomplishing a specified purpose

[ISO/AFNOR Dictionary of Computer Science]
3.1.23
function block (function block instance)

software functional unit comprising an individual, named copy of a data structure and

associated operations specified by a corresponding FB type
[IEC 61499-1]
NOTE Typical operat
...

SLOVENSKI STANDARD
SIST EN 61804-2:2007
01-december-2007
1DGRPHãþD
SIST EN 61804-2:2004

Funkcijski bloki (FB) za nadzor procesov - 2. del: Specifikacije koncepta FB (IEC

61804-2:2006)
Function blocks (FB) for process control - Part 2: Specification of FB concept
Funktionsbausteine für die Prozessautomation - Teil 2: Festlegung des
Funktionsbausteinkonzepts

Blocs fonction pour les processus industriels - Partie 2: Spécification du concept de bloc

fonction
Ta slovenski standard je istoveten z: EN 61804-2:2007
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
SIST EN 61804-2:2007 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
EUROPEAN STANDARD
EN 61804-2
NORME EUROPÉENNE
June 2007
EUROPÄISCHE NORM
ICS 25.040.40; 35.240.50 Partially supersedes EN 61804-2:2004
English version
Function blocks (FB) for process control -
Part 2: Specification of FB concept
(IEC 61804-2:2006)
Blocs fonction Funktionsbausteine
pour les processus industriels - für die Prozessautomation -
Partie 2: Spécification du concept Teil 2: Festlegung
de bloc fonction des Funktionsbausteinkonzepts
(IEC 61804-2:2006)
(CEI 61804-2:2006)

This European Standard was approved by CENELEC on 2007-05-01. 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 Central Secretariat 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 Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Cyprus, the

Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,

Sweden, Switzerland and the United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2007 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 61804-2:2007 E
---------------------- Page: 2 ----------------------
EN 61804-2:2007 - 2 -
Foreword

The text of the International Standard IEC 61804-2:2006, prepared by SC 65C, Industrial networks, of

IEC TC 65, Industrial-process measurement and control, was submitted to the formal vote and was

approved by CENELEC as EN 61804-2 on 2007-05-01 without any modification.

This European Standard, together with EN 61804-3:2007, supersedes EN 61804-2:2004.

EN 61804-2:2007 includes the following significant technical changes with respect to EN 61804-2:2004:

– transfer of the EDDL-specific clauses to EN 61804-3;

– the FB-specific subclauses 4.1 and 4.2 as well as Clauses 5, 6, 7 and 8 are unchanged.

The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2008-05-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2010-05-01

The International Electrotechnical Commission (IEC) and CENELEC draw attention to the fact that it is

claimed that compliance with this document may involve the use of patents
U.S. Patent No. 5,333,114
U.S. Patent No. 5,485,400
U.S. Patent No. 5,825,664
U.S. Patent No. 5,909,368
U.S. Patent Pending No. 08/916,178
Australian Patent No. 638507
Canadian Patent No. 2,066,743
European Patent No. 0495001
Validated in:
UK – Patent No. 0495001
France – Patent No. 0495001
Germany – Patent No. 69032954.7
Netherlands – Patent No. 0495001
Japan Patent No. 3137643

The IEC and CENELEC take no position concerning the evidence, validity and scope of this patent right.

The holder of this patent right has assured the IEC that he is willing to negotiate licenses under

reasonable and non-discriminatory terms and conditions with applicants throughout the world. In this

respect, the statement of the holder of this patent right is registered with IEC. Information may be

obtained from:
Fieldbus Foundation,
9390 Research Boulevard, Suite II-250,
Austin, Texas, USA 78759,
Attention: President.
---------------------- Page: 3 ----------------------
- 3 - EN 61804-2:2007

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights other than those identified above. IEC and CENELEC shall not be held responsible for

identifying any or all such patent rights.
Annex ZA has been added by CENELEC.
__________
Endorsement notice

The text of the International Standard IEC 61804-2:2006 was approved by CENELEC as a European

Standard without any modification.
__________
---------------------- Page: 4 ----------------------
EN 61804-2:2007 - 4 -
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

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.

NOTE Where an International Publication has been modified by common modifications, indicated by (mod), the relevant EN/HD

applies.
Publication Year Title EN/HD Year
IEC 60050-351 1998 International Electrotechnical Vocabulary - -
(IEV) –
Part 351: Automatic control
1) 2)
IEC 60584-1 - Thermocouples – EN 60584-1 1995
Part 1: Reference tables
IEC 61131-3 2003 Programmable controllers – EN 61131-3 2003
Part 3: Programming languages
IEC 61158 Series Digital data communications for EN 61158 Series
measurement and control - Fieldbus for use
in industrial control systems
IEC 61499-1 2005 Function blocks – EN 61499-1 2005
Part 1: Architecture
IEC 61499-2 2005 Function blocks – EN 61499-2 2005
Part 2: Software tools requirements
IEC/TS 61804-1 2003 Function blocks (FB) for process control – - -
Part 1: Overview of system aspects
ISO/IEC 7498-1 1994 Information technology - Open systems EN ISO/IEC 7498-1 1995
interconnection - Basic reference model –
Part 1: The basic model
ISO/IEC 9899 - Programming languages - C - -
ISO/IEC 10646-1 - Information technology - Universal Multiple-- -
Octet Coded Character Set (UCS) –
Part 1: Architecture and Basic Multilingual
Plane
Undated reference.
Valid edition at date of issue.
---------------------- Page: 5 ----------------------
INTERNATIONAL IEC
STANDARD 61804-2
Second edition
2006-09
Function blocks (FB) for process control –
Part 2:
Specification of FB concept
 IEC 2006  Copyright - all rights reserved

No part of this publication may be reproduced or utilized in any form or by any means, electronic or

mechanical, including photocopying and microfilm, without permission in writing from the publisher.

International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland

Telephone: [phone] Telefax: [phone] E-mail: [e-mail] Web: www.iec.ch

PRICE CODE
Commission Electrotechnique Internationale XA
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue
---------------------- Page: 6 ----------------------
– 2 – 61804-2  IEC:2006(E)
CONTENTS

FOREWORD...........................................................................................................................4

INTRODUCTION.....................................................................................................................6

1 Scope...............................................................................................................................7

2 Normative references .......................................................................................................7

3 Terms, definitions and abbreviated terms and acronyms...................................................8

3.1 Terms and definitions ..............................................................................................8

3.2 Abbreviated terms and acronyms ..........................................................................14

4 General Function Block (FB) definition and EDD model ..................................................14

4.1 Device structure (device model) ............................................................................14

4.2 Block combinations ...............................................................................................25

5 Detailed block definition .................................................................................................28

5.1 General .................................................................................................................28

5.2 Application FBs .....................................................................................................28

5.3 Component FBs ....................................................................................................36

5.4 Technology Block ..................................................................................................36

5.5 Device (Resource) Block .......................................................................................45

5.6 Algorithms common to all blocks ...........................................................................47

6 FB Environment..............................................................................................................49

7 Mapping to System Management....................................................................................49

8 Mapping to Communication ............................................................................................49

9 Conformance statement..................................................................................................51

Annex A (informative) Parameter description .......................................................................52

Annex B (normative) IEC 61804 Conformance Declaration ..................................................58

Bibliography..........................................................................................................................59

Figure 1 – Position of the IEC 61804 series related to other standards and products ..............6

Figure 2 – FB structure is derived out of the process (P&ID view) .........................................15

Figure 3 – FB structure may be distributed between devices.................................................16

Figure 4 – IEC 61804 FBs can be implemented in different devices ......................................17

Figure 5 – General components of devices ...........................................................................17

Figure 6 – Block types of IEC 61804 .....................................................................................18

Figure 7 – IEC 61804 block overview (graphical representation not normative) .....................19

Figure 8 – UML class diagram of the device model ...............................................................22

Figure 9 – Measurement process signal flow.........................................................................26

Figure 10 – Actuation process signal flow .............................................................................26

Figure 11 – Application process signal flow...........................................................................27

Figure 12 – Analog Input FB .................................................................................................28

Figure 13 – Analog Output FB...............................................................................................30

Figure 14 – Discrete input FB ...............................................................................................31

Figure 15 – Discrete Output FB.............................................................................................32

---------------------- Page: 7 ----------------------
61804-2  IEC:2006(E) – 3 –

Figure 16 – Calculation FB....................................................................................................34

Figure 17 – Control FB..........................................................................................................35

Figure 18 – Temperature Technology Block ..........................................................................36

Figure 19 – Pressure Technology Block ................................................................................39

Figure 20 – Modulating actuation technology block ...............................................................41

Figure 21 – On/Off Actuation Technology Block ....................................................................43

Figure 22 – Harel state chart ................................................................................................46

Figure 23 – Application structure of ISO OSI Reference Model .............................................49

Figure 24 – Client/Server relationship in terms of OSI Reference Model ...............................50

Figure 25 – Mapping of IEC 61804 FBs to APOs...................................................................50

Table 1 – References of model elements ..............................................................................21

Table 2 – Variables and parameter description template .......................................................24

Table 3 – Example of temperature sensors of Sensor_Type..................................................37

Table 4 – Device status state table .......................................................................................45

Table 5 – Device status transition table ................................................................................46

Table A.1 – Parameter description ........................................................................................52

Table B.1 – Conformance (sub)clause selection table...........................................................58

Table B.2 – Contents of (sub)clause selection tables ............................................................58

---------------------- Page: 8 ----------------------
– 4 – 61804-2  IEC:2006(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
FUNCTION BLOCKS (FB) FOR PROCESS CONTROL –
Part 2: Specification of FB concept
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote

international co-operation on all questions concerning standardization in the electrical and electronic fields. To

this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,

Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC

Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested

in the subject dealt with may participate in this preparatory work. International, governmental and non-

governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely

with the International Organization for Standardization (ISO) in accordance with conditions determined by

agreement between the two organizations.

2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

consensus of opinion on the relevant subjects since each technical committee has representation from all

interested IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

misinterpretation by any end user.

4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

transparently to the maximum extent possible in their national and regional publications. Any divergence

between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in

the latter.

5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any

equipment declared to be in conformity with an IEC Publication.

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.

The International Electrotechnical Commission (IEC) draws attention to the fact that it is claimed that compliance

with this document may involve the use of patents
U.S. Patent No. 5,333,114
U.S. Patent No. 5,485,400
U.S. Patent No. 5,825,664
U.S. Patent No. 5,909,368
U.S. Patent Pending No. 08/916,178
Australian Patent No. 638507
Canadian Patent No. 2,066,743
European Patent No. 0495001
Validated in:
UK – Patent No. 0495001
France – Patent No. 0495001
Germany – Patent No. 69032954.7
Netherlands – Patent No. 0495001
Japan Patent No. 3137643
---------------------- Page: 9 ----------------------
61804-2  IEC:2006(E) – 5 –

IEC take no position concerning the evidence, validity and scope of this patent right. The holder of this patent right

has assured the IEC that he is willing to negotiate licenses under reasonable and non-discriminatory terms and

conditions with applicants throughout the world. In this respect, the statement of the holder of this patent right is

registered with IEC. Information may be obtained from:
Fieldbus Foundation,
9390 Research Boulevard, Suite II-250,
Austin, Texas, USA 78759,
Attention: President.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights

other than those identified above. IEC shall not be held responsible for identifying any or all such patent rights.

This International Standard has been prepared by subcommittee 65C: Digital communications,

of IEC technical committee 65: Industrial-process measurement and control.

This second edition, together with the first edition of IEC 61804-3, cancels and replaces the

first edition of IEC 61804-2 published in 2004. This edition constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:
a) transfer of the EDDL-specific clauses to IEC 61804-3;

b) the FB-specific subclauses 4.1 and 4.2 as well as Clauses 5, 6, 7 and 8 are unchanged.

The text of this standard is based on the following documents:
CDV Report on voting
65C/405/CDV 65C/420/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 ISO/IEC Directives, Part 2.

The list of all parts of the IEC 61804 series, under the general title Function Blocks (FB) for

process control, can be found on the IEC website.

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 publication may be issued at a later date.
---------------------- Page: 10 ----------------------
– 6 – 61804-2  IEC:2006(E)
INTRODUCTION

This part of IEC 61804 provides conceptual Function Block specifications, which can be

mapped to specific communication systems, and their accompanying definitions by industrial

groups.

The EDDL fills the gap between the conceptual FB specification of IEC 61804-2 and a product

implementation. Figure 1 shows these aspects.
Abstract models IEC 61499-1 ISO 15745-1
Conceptual FB
IEC
IEC 61804 2
specification for
61804 - 3
FB concept
the process
EDDL
sector
IEC/TR
FIP
Controlnet
Solutions FF PROFI-
companion
FB BUS 61804 - 4
(technology)
standards
...
application PA profile
Interoperability
profiles
Guideline
Implementation
Products
IEC 1507/06

Figure 1 – Position of the IEC 61804 series related to other standards and products

---------------------- Page: 11 ----------------------
61804-2  IEC:2006(E) – 7 –
FUNCTION BLOCKS (FB) FOR PROCESS CONTROL –
Part 2: Specification of FB concept
1 Scope

This part of IEC 61804 is applicable to Function Blocks (FB) for process control.

This standard specifies FB by using the result of harmonization work as regards several

elements:

c) the device model which defines the components of an IEC 61804-2 conformant device;

d) conceptual specifications of FBs for measurement, actuation and processing. This

includes general rules for the essential features to support control, whilst avoiding details

which stop innovation as well as specialization for different industrial sectors.

This standard defines a subset of the requirements of IEC 61804-1 (hereafter referred to as

Part 1) only, while Part 1 describes requirements for a distributed system.

The conformance statement in Annex B, which covers the conformance declaration, is related

to this standard only. Requirements of Part 1 are not part of these conformance declarations.

The standardization work for FB was carried out by harmonizing the description of concepts of

existing technologies. It results in an abstract level that allowed the definition of the common

features in a unique way. This abstract vision is called here the conceptual FB specification

and mapped to specific communication systems and their accompanying definitions by the

industrial groups. This standard is also based on the abstract definitions of IEC 61499-1.

NOTE This standard can be mapped to ISO 15745-1.

There are solutions on the market today, which fulfil the requirements of this standard and

show how the conceptual specification is implemented in a given technology. New
technologies will need to find equivalent solutions (see Figure 4).
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 60584-1, Thermocouples – Part 1: Reference tables
IEC 61131-3:2003, Programmable controllers – Part 3: Programming languages

IEC 61158 (all parts), Digital data communications for measurement and control – Fieldbus for

use in industrial control systems
IEC 61499-1:2005, Function blocks – Part 1: Architecture
IEC 61499-2:2005, Function blocks – Part 2: Software tools requirements
---------------------- Page: 12 ----------------------
– 8 – 61804-2  IEC:2006(E)

IEC 61804-1:2003, Function blocks (FB) for process control − Part 1: Overview of system

aspects

ISO/IEC 7498-1:1994, Information technology – Open Systems Interconnection – Basic

Reference Model: The Basic Model
ISO/IEC 9899, Programming languages − C

ISO/IEC 10646-1, Information technology – Universal Multiple-Octet Coded Character Set

(UCS) – Part 1: Architecture and Basic Multilingual Plane
3 Terms, definitions, and abbreviated terms and acronyms
3.1 Terms and definitions

For the purposes of this document, the following terms and definitions, some of which have

been compiled from the referenced documents, apply.
3.1.1
algorithm

finite set of well-defined rules for the solution of a problem in a finite number of operations

3.1.2
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.

3.1.3
application function block
FB which has no input or output to the process
3.1.4
attribute

property or characteristic of an entity, for instance, the version identifier of an FB type

specification
[IEC 61499-1]

NOTE The formal description of attributes is part of the solution profiles to achieve domain-specific

interoperability. IEC 61804 defines the general rules to define the attributes and specifies the EDDL to describe

attributes, which may be described in solution profiles.
3.1.5
component function block

FB instance which is used in the specification of an algorithm of a composite FB type

NOTE A component FB can be an FB or a composite FB type.
3.1.6
composite FB type

FB type whose algorithm is expressed entirely in terms of interconnected component FBs and

variables
[IEC 61499-1]
---------------------- Page: 13 ----------------------
61804-2  IEC:2006(E) – 9 –
3.1.7
configuration (of a system or device)

step in system design: selecting functional units, assigning their locations and defining their

interconnections
[IEC 61499-1]
3.1.8
data

representation of facts, concepts or instructions in a formalized manner suitable for

communication, interpretation or processing by human beings or by automatic means

[ISO/AFNOR Dictionary of Computer Science]
3.1.9
data connection
association established between functional units for conveyance of data
[IEC 61499-1]
3.1.10
data input
interface of an FB which receives data from a data connection
[IEC 61499-1]
3.1.11
data output
interface of an FB, which supplies data to a data connection
[IEC 61499-1]
3.1.12
data type
set of values together with a set of permitted operations
[ISO 2382 series]
3.1.13
device

independent physical entity capable of performing one or more specified functions in a

particular context and delimited by its interfaces
[IEC 61499-1]
3.1.14
device block
FB which has no input and no output
3.1.15
device management application

application whose primary function is the management of a multiple resources within a device

[IEC 61499-1]
3.1.16
Electronic Device Description Language (EDDL)
methodology for describing parameter(s) of an automation system component
---------------------- Page: 14 ----------------------
– 10 – 61804-2  IEC:2006(E)
3.1.17
Electronic Device Description (EDD)

data collection containing the device parameter(s), their dependencies, their graphical

representation and a description of the data sets which are transferred.

NOTE The Electronic Device Description is created using the Electronic Device Description Language (EDDL).

3.1.18
entity

particular thing, such as a person, place, process, object, concept, association, or event

[IEC 61499-1]
3.1.19
event

instantaneous occurrence that is significant to scheduling the execution of an algorithm

[IEC 61499-1]

NOTE The execution of an algorithm may make use of variables associated with an event.

3.1.20
exception
event that causes suspension of normal execution
[IEC 61499-1]
3.1.21
function
specific purpose of an entity or its characteristic action
[IEC 61499-1]
3.1.22
functional unit

entity of hardware or software, or both, capable of accomplishing a specified purpose

[ISO/AFNOR Dictionary of Computer Science]
3.1.23
function block (function block instance)

software functional unit comprising an individual, named copy of a data structure and

associated operations specified by a corresponding FB type
[IEC 61499-1]

NOTE Typical operations of an FB include modification of the values of the data in its associated data structure.

3.1.24
function block diagram

network in which the nodes are function block instances, variables, literals, and events

NOTE This is not the same as the function block diagram defined in IEC 61131-3.
[IEC 61499-1]
3.1.25
hardware
physical equipment, as opposed to programs, procedures, rules and associated
documentation
[ISO/AFNOR Dictionary of Computer Science]
-----
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