SIST EN 61131-3:2013

SLOVENSKI STANDARD
01-julij-2013
1DGRPHãþD
SIST EN 61131-3:2004
Programirljivi krmilniki - 3. del: Programski jeziki (IEC 61131-3:2013)
Programmable controllers - Part 3: Programming languages (IEC 61131-3:2013)
Speicherprogrammierbare Steuerungen - Teil 3: Programmiersprachen (IEC 61131-
3:2013)
Automates programmables - Partie 3: Langages de programmation (CEI 61131-3:2013)
Ta slovenski standard je istoveten z: EN 61131-3:2013
ICS:
25.040.40 Merjenje in krmiljenje Industrial process
industrijskih postopkov measurement and control
35.240.50 Uporabniške rešitve IT v IT applications in industry
industriji
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 61131-3
NORME EUROPÉENNE
May 2013
EUROPÄISCHE NORM
ICS 25.040; 35.240.50 Supersedes EN 61131-3:2003

English version
Programmable controllers -
Part 3: Programming languages
(IEC 61131-3:2013)
Automates programmables -  Speicherprogrammierbare Steuerungen -
Partie 3: Langages de programmation Teil 3: Programmiersprachen
(CEI 61131-3:2013) (IEC 61131-3:2013)

This European Standard was approved by CENELEC on 2013-03-27. CENELEC members are bound to comply
with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
the status of a national standard without any alteration.

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

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

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

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

Management Centre: Avenue Marnix 17, B - 1000 Brussels

© 2013 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61131-3:2013 E
Foreword
The text of document 65B/858/FDIS, future edition 3 of IEC 61131-3, prepared by IEC TC 65 "Industrial-
process measurement, control and automation" was submitted to the IEC-CENELEC parallel vote and
approved by CENELEC as EN 61131-3:2013.
The following dates are fixed:
(dop) 2013-12-27
• latest date by which the document has
to be implemented at national level by
publication of an identical national
standard or by endorsement
• latest date by which the national (dow) 2016-03-27
standards conflicting with the

document have to be withdrawn
This document supersedes EN 61131-3:2003.
and conversion functions, references, name spaces and the object oriented features of classes abd function
blocks. See Annex B.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such patent
rights.
Endorsement notice
The text of the International Standard IEC 61131-3:2013 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:
IEC 60848 NOTE  Harmonised as EN 60848.
IEC 61499 series NOTE  Harmonised in EN 61499 series.

- 3 - EN 61131-3:2013
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.

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

IEC 61131-1 - Programmable controllers - EN 61131-1 -
Part 1: General information
IEC 61131-5 - Programmable controllers - EN 61131-5 -
Part 5: Communications
ISO/IEC 10646 2012 Information technology - - -
Universal Coded Character Set (UCS)

ISO/IEC/IEEE 60559 - Information technology - Microprocessor - -
Systems - Floating-Point arithmetic

IEC 61131-3 ®
Edition 3.0 2013-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Programmable controllers –
Part 3: Programming languages
Automates programmables –
Partie 3: Langages de programmation

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XH
ICS 25.040; 35.240.50 ISBN 978-2-83220-661-4

– 2 – 61131-3 © IEC:2013
CONTENTS
FOREWORD . 7
1 Scope . 9
2 Normative references . 9
3 Terms and definitions . 9
4 Architectural models . 18
4.1 Software model . 18
4.2 Communication model . 19
4.3 Programming model . 20
5 Compliance . 22
5.1 General . 22
5.2 Feature tables . 22
5.3 Implementer’s compliance statement . 22
6 Common elements . 24
6.1 Use of printed characters . 24
6.1.1 Character set . 24
6.1.2 Identifiers . 24
6.1.3 Keywords . 24
6.1.4 Use of white space . 25
6.1.5 Comments . 25
6.2 Pragma . 26
6.3 Literals – External representation of data . 26
6.3.1 General . 26
6.3.2 Numeric literals and string literals . 26
6.3.3 Character string literals . 28
6.3.4 Duration literal . 29
6.3.5 Date and time of day literal . 30
6.4 Data types . 30
6.4.1 General . 30
6.4.2 Elementary data types (BOOL, INT, REAL, STRING, etc.) . 30
6.4.3 Generic data types . 33
6.4.4 User-defined data types . 34
6.5 Variables . 47
6.5.1 Declaration and initialization of variables . 47
6.5.2 Variable sections . 49
6.5.3 Variable length ARRAY variables . 51
6.5.4 Constant variables . 53
6.5.5 Directly represented variables ( % ) . 54
6.5.6 Retentive variables (RETAIN, NON_RETAIN) . 56
6.6 Program organization units (POUs) . 58
6.6.1 Common features for POUs . 58
6.6.2 Functions. 70
6.6.3 Function blocks . 99
6.6.4 Programs . 117
6.6.5 Classes . 118

61131-3 © IEC:2013 – 3 –
6.6.6 Interface . 137
6.6.7 Object oriented features for function blocks . 146
6.6.8 Polymorphism . 152
6.7 Sequential Function Chart (SFC) elements . 155
6.7.1 General . 155
6.7.2 Steps . 155
6.7.3 Transitions . 157
6.7.4 Actions . 160
6.7.5 Rules of evolution . 168
6.8 Configuration elements . 176
6.8.1 General . 176
6.8.2 Tasks . 180
6.9 Namespaces . 186
6.9.1 General . 186
6.9.2 Declaration . 186
6.9.3 Usage . 192
6.9.4 Namespace directive USING . 192
7 Textual languages . 195
7.1 Common elements . 195
7.2 Instruction list (IL) . 195
7.2.1 General . 195
7.2.2 Instructions . 195
7.2.3 Operators, modifiers and operands . 196
7.2.4 Functions and function blocks . 198
7.3 Structured Text (ST) . 201
7.3.1 General . 201
7.3.2 Expressions . 201
7.3.3 Statements . 203
8 Graphic languages . 208
8.1 Common elements . 208
8.1.1 General . 208
8.1.2 Representation of variables and instances . 209
8.1.3 Representation of lines and blocks . 211
8.1.4 Direction of flow in networks . 212
8.1.5 Evaluation of networks . 213
8.1.6 Execution control elements . 214
8.2 Ladder diagram (LD) . 215
8.2.1 General . 215
8.2.2 Power rails . 216
8.2.3 Link elements and states . 216
8.2.4 Contacts . 216
8.2.5 Coils . 218
8.2.6 Functions and function blocks . 219
8.2.7 Order of network evaluation . 219
8.3 Function Block Diagram (FBD) . 219
8.3.1 General . 219
8.3.2 Combination of elements . 219
8.3.3 Order of network evaluation . 220
Annex A (normative) Formal specification of the languages elements . 221

– 4 – 61131-3 © IEC:2013
Annex B (informative) List of major changes and extensions of the third edition . 228
Bibliography . 229

Figure 1 – Software model . 18
Figure 2 – Communication model . 20
Figure 3 – Combination of programmable controller language elements . 21
Figure 4 – Implementer’s compliance statement (Example) . 23
Figure 5 – Hierarchy of the generic data types . 34
Figure 6 – Initialization by literals and constant expressions (Rules) . 35
Figure 7 – Variable declaration keywords (Summary) . 50
Figure 8 – Usage of VAR_GLOBAL, VAR_EXTERNAL and CONSTANT (Rules) . 51
Figure 9 – Conditions for the initial value of a variable (Rules) . 57
Figure 10 – Formal and non-formal representation of call (Examples) . 63
Figure 11 – Data type conversion rules – implicit and/or explicit (Summary) . 67
Figure 12 – Supported implicit type conversions . 68
Figure 13 – Usage of function block input and output parameters (Rules) . 108
Figure 14 – Usage of function block input and output parameters (Illustration of rules) . 109
Figure 15 – Standard timer function blocks – timing diagrams (Rules) . 116
Figure 16 – Overview of inheritance and interface implementation . 119
Figure 17 – Inheritance of classes (Illustration) . 128
Figure 18 – Interface with derived classes (Illustration) . 138
Figure 19 – Inheritance of interface and class (Illustration) . 143
Figure 20 – Function block with optional body and methods (Illustration) . 149
Figure 21 – Inheritance of function block body with SUPER() (Example) . 151
Figure 22 – ACTION_CONTROL function block – External interface (Summary) . 165
Figure 23 – ACTION_CONTROL function block body (Summary). 166
Figure 24 – Action control (Example) . 168
Figure 25 – SFC evolution (Rules) . 174
Figure 26 – SFC errors (Example) . 175
Figure 27 – Configuration (Example) . 177
Figure 28 – CONFIGURATION and RESOURCE declaration (Example) . 180
Figure 29 – Accessibility using namespaces (Rules) . 189
Figure 30 – Common textual elements (Summary) . 195

Table 1 – Character set . 24
Table 2 – Identifiers . 24
Table 3 – Comments . 25
Table 4 – Pragma . 26
Table 5 – Numeric literals . 27
Table 6 – Character string literals . 28
Table 7 – Two-character combinations in character strings . 29
Table 8 – Duration literals . 29
Table 9 – Date and time of day literals . 30

61131-3 © IEC:2013 – 5 –
Table 10 – Elementary data types . 31
Table 11 – Declaration of user-defined data types and initialization . 35
Table 12 – Reference operations . 46
Table 13 – Declaration of variables . 48
Table 14 – Initialization of variables . 49
Table 15 – Variable-length ARRAY variables . 52
Table 16 – Directly represented variables . 54
Table 17 – Partial access of ANY_BIT variables . 60
Table 18 – Execution control graphically using EN and ENO . 65
Table 19 – Function declaration . 72
Table 20 – Function call . 74
Table 21 – Typed and overloaded functions . 76
Table 22 – Data type conversion function . 78
Table 23 – Data type conversion of numeric data types . 80
Table 24 – Data type conversion of bit data types . 82
Table 25 – Data type conversion of bit and numeric types . 83
Table 26 – Data type conversion of date and time types . 85
Table 27 – Data type conversion of character types . 86
Table 28 – Numerical and arithmetic functions . 87
Table 29 – Arithmetic functions . 88
Table 30 – Bit shift functions . 89
Table 31 – Bitwise Boolean functions . 89
d
Table 32 – Selection functions . 90
Table 33 – Comparison functions . 91
Table 34 – Character string functions . 92
Table 35 – Numerical functions of time and duration data types . 93
Table 36 – Additional functions of time data types CONCAT and SPLIT . 94
Table 37 – Function for endianess conversion . 98
Table 38 – Functions of enumerated data types . 98
Table 39 – Validate functions . 99
Table 40 – Function block type declaration . 100
Table 41 – Function block instance declaration . 104
Table 42 – Function block call . 105
a
Table 43 – Standard bistable function blocks . 112
Table 44 – Standard edge detection function blocks . 113
Table 45 – Standard counter function blocks . 113
Table 46 – Standard timer function blocks . 115
Table 47 – Program declaration . 117
Table 48 – Class . 120
Table 49 – Class instance declaration . 122
Table 50 – Textual call of methods – Formal and non-formal parameter list . 125
Table 51 – Interface . 137
Table 52 – Assignment attempt . 146

– 6 – 61131-3 © IEC:2013
Table 53 – Object oriented function block . 147
Table 54 – SFC step . 156
Table 55 – SFC transition and transition condition . 158
Table 56 – SFC declaration of actions . 160
Table 57 – Step/action association . 162
Table 58 – Action block . 163
Table 59 – Action qualifiers . 163
Table 60 – Action control features . 168
Table 61 – Sequence evolution – graphical . 169
Table 62 – Configuration and resource declaration . 178
Table 63 – Task . 182
Table 64 – Namespace . 191
Table 65 – Nested namespace declaration options . 192
Table 66 – Namespace directive USING . 194
Table 67 – Parenthesized expression for IL language . 197
Table 68 – Instruction list operators . 197
Table 69 – Calls for IL language . 199
Table 70 – Standard function block operators for IL language . 201
Table 71 – Operators of the ST language . 202
Table 72 – ST language statements . 203
Table 73 – Graphic execution control elements . 215
Table 74 – Power rails and link elements . 216
Table 75 – Contacts . 217
Table 76 – Coils . 218

61131-3 © IEC:2013 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PROGRAMMABLE CONTROLLERS –
Part 3: Programming languages
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 interna-
tional 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, Tech-
nical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publica-
tion(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 Interna-
tional 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 inter-
ested 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 misinter-
pretation 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 be-
tween any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and ex-
penses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC Publica-
tions.
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 61131-3 has been prepared by subcommittee 65B: Measurement
and control devices, of IEC technical committee 65: Industrial-process measurement, control
and automation.
This third edition of IEC 61131-3 cancels and replaces the second edition, published in 2003.
This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
This third edition is a compatible extension of the second edition. The main extensions are
new data types and conversion functions, references, name spaces and the object oriented
features of classes and function blocks. See Annex B.

– 8 – 61131-3 © IEC:2013
The text of this standard is based on the following documents:

FDIS Report on voting
65B/858/FDIS 65B/863/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all the parts in the IEC 61131 series, published under the general title Programmable
controllers can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data re-
lated to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
61131-3 © IEC:2013 – 9 –
PROGRAMMABLE CONTROLLERS –
Part 3: Programming languages
1 Scope
This part of IEC 61131 specifies syntax and semantics of programming languages for pro-
grammable controllers as defined in Part 1 of IEC 61131.
The functions of program entry, testing, monitoring, operating system, etc., are specified in
Part 1 of IEC 61131.
This part of IEC 61131 specifies the syntax and semantics of a unified suite of programming
languages for programmable controllers (PCs). This suite consists of two textual languages,
Instruction List (IL) and Structured Text (ST), and two graphical languages, Ladder Diagram
(LD) and Function Block Diagram (FBD).
An additional set of graphical and equivalent textual elements named Sequential Function
Chart (SFC) is defined for structuring the internal organization of programmable controller
programs and function blocks. Also, configuration elements are defined which support the in-
stallation of programmable controller programs into programmable controller systems.
In addition, features are defined which facilitate communication among programmable control-
lers and other components of automated systems.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amend-
ments) applies.
IEC 61131-1, Programmable controllers – Part 1: General information
IEC 61131-5, Programmable controllers – Part 5: Communications
ISO/IEC 10646:2012, Information technology – Universal Coded Character Set (UCS)
ISO/IEC/IEEE 60559, Information technology – Microprocessor Systems – Floating-Point
arithmetic
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61131-1 and the
following apply.
3.1
absolute time
combination of time of day and date information

– 10 – 61131-3 © IEC:2013
3.2
access path
association of a symbolic name with a variable for the purpose of open communication
3.3
action
Boolean variable or a collection of operations to be performed, together with an associated
control structure
3.4
action block
graphical language element which utilizes a Boolean input variable to determine the value of a
Boolean output variable or the enabling condition for an action, according to a predetermined
control structure
3.5
aggregate
structured collection of data objects forming a data type
[SOURCE: ISO/AFNOR:1989]
3.6
array
aggregate that consists of data objects, with identical attributes, each of which may be
uniquely referenced by subscripting
[SOURCE: ISO/AFNOR:1989]
3.7
assignment
mechanism to give a value to a variable or to an aggregate
[SOURCE: ISO/AFNOR:1989]
3.8
base type
data type, function block type or class from which further types are inherited/derived
3.9
based number
number represented in a specified base other than ten
3.10
binary coded decimal
BCD
encoding for decimal numbers in which each digit is represented by its own binary sequence
3.11
bistable function block
function block with two stable states controlled by one or more inputs
3.12
bit string
data element consisting of one or more bits
3.13
bit string literal
literal that directly represents a bit string value of data type BOOL, BYTE, WORD, DWORD, or
LWORD
61131-3 © IEC:2013 – 11 –
3.14
body
set of operations of the program organization unit
3.15
call
language construct causing the execution of a function, function block, or method
3.16
character string
aggregate that consists of an ordered sequence of characters
3.17
character string literal
literal that directly represents a character or character string value of data type CHAR,
WCHAR, STRING, or WSTRING
3.18
class
program organization unit consisting of:
• the definition of a data structure,
• a set of methods to be performed upon the data structure, and
3.19
comment
language construct for the inclusion of text having no impact on the execution of the program
[SOURCE: ISO/AFNOR:1989]
3.20
configuration
language element corresponding to a programmable controller system
3.21
constant
language element which declares a data element with a fixed value
3.22
counter function block
function block which accumulates a value for the number of changes sensed at one or more
specified inputs
3.23
data type
set of values together with a set of permitted operations
[SOURCE: ISO/AFNOR:1989]
3.24
date and time
date within the year and the time of day represented as a single language element
3.25
declaration
mechanism for establishing the definition of a language element

– 12 – 61131-3 © IEC:2013
3.26
delimiter
character or combination of characters used to separate program language elements
3.27
derived class
class created by inheritance from another class
Note 1 to entry: Derived class is also named extended class or child class.
3.28
derived data type
data type created by using another data type
3.29
derived function block type
function block type created by inheritance from another function block type
3.30
direct representation
means of representing a variable in a programmable controller program from which an imple-
mentation-specified correspondence to a physical or logical location may be determined di-
rectly
3.31
double word
data element containing 32 bits
3.32
dynamic binding
situation in which the instance of a method call is retrieved during runtime according to the
actual type of an instance or interface
3.33
evaluation
process of establishing a value for an expression or a function, or for the outputs of a network
or function block instance, during program execution
3.34
execution control element
language element which controls the flow of program execution
3.35
falling edge
change from 1 to 0 of a Boolean variable
3.36
function
language element which, when executed, typically yields one data element result and possibly
additional output variables
3.37
function block instance
instance of a function block type
3.38
function block type
language element consisting of:

61131-3 © IEC:2013 – 13 –
− the definition of a data structure partitioned into input, output, and internal variables; and
− a set of operations or a set of methods to be performed upon the elements of the data
structure when an instance of the function block type is called
3.39
function block diagram
network in which the nodes are function block instances, graphically represented functions or
method calls, variables, literals, and labels
3.40
generic data type
data type which represents more than one type of data
3.41
global variable
variable whose scope is global
3.42
hierarchical addressing
direct representation of a data element as a member of a physical or logical hierarchy
EXAMPLE A point within a module which is contained in a rack, which in turn is contained in a cubicle, etc.
3.43
identifier
combination of letters, numbers, and underscore characters which begins with a letter or un-
derscore and which names a language element
3.44
implementation
product version of a PLC or the programming and debugging tool provided by the Implementer
3.45
Implementer
manufacturer of the PLC or the programming and debugging tool provided to the user to pro-
gram a PLC application
3.46
inheritance
creation of a new class, function block type or interface based on an existing class, function
block type or interface, respectively
3.47
initial value
value assigned to a variable at system start-up
3.48
in-out variable
variable which is used to supply a value to a program organization unit and which is addition-
ally used to return a value from the program organization unit
3.49
input variable
variable which is used to supply a value to a program organization unit except for class

– 14 – 61131-3 © IEC:2013
3.50
instance
individual, named copy of the data structure associated with a function block type, class, or
program type, which keeps its values from one call
...