EN 61131-3:2003

SLOVENSKI SIST EN 61131-3:2004

STANDARD
marec 2004
Programmable controllers - Part 3: Programming languages
ICS 25.040.40; 35.240.50 Referenčna številka
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

EUROPEAN STANDARD EN 61131-3
NORME EUROPÉENNE
EUROPÄISCHE NORM March 2003
ICS 25.040; 35.240.50 Supersedes EN 61131-3:1993

English version
Programmable controllers
Part 3: Programming languages
(IEC 61131-3:2003)
Automates programmables Speicherprogrammierbare Steuerungen
Partie 3: Langages de programmation Teil 3: Programmiersprachen
(CEI 61131-3:2003) (IEC 61131-3:2003)

This European Standard was approved by CENELEC on 2002-12-01. 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, Czech Republic,
Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta,
Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and 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

© 2003 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 61131-3:2003 E
Foreword
The text of document 65B/456/FDIS, future edition 2 of IEC 61131-3, prepared by SC 65B, Devices, of
IEC TC 65, Industrial-process measurement and control, was submitted to the IEC-CENELEC parallel
vote and was approved by CENELEC as EN 61131-3 on 2002-12-01.

This European Standard supersedes EN 61131-3:1993.

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) 2003-10-01

– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2005-12-01

Annexes designated "normative" are part of the body of the standard.
Annexes designated "informative" are given for information only.
In this standard, annexes A, B, C, D, E and ZA are normative and annexes F and G are informative.
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 61131-3:2003 was approved by CENELEC as a European
Standard without any modification.
__________
- 3 - EN 61131-3:2003
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
This European Standard incorporates by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions of any
of these publications apply to this European Standard only when incorporated in it by amendment or
revision. For undated references the latest edition of the publication referred to applies (including
amendments).
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 60050 Series International Electrotechnical - -
Vocabulary
IEC 60559 1989 Binary floating-point arithmetic for HD 592 S1 1991
microprocessor systems
IEC 60617-12 1997 Graphical symbols for diagrams EN 60617-12 1998
Part 12: Binary logic elements

IEC 60617-13 1993 Part 13: Analogue elements EN 60617-13 1993

IEC 60848 2002 GRAFCET specification language for EN 60848 2002
sequential function charts
1) 2)
IEC 61131-1 - Programmable controllers EN 61131-1 1994
Part 1: General information
1) 2)
IEC 61131-5 - Part 5: Communications EN 61131-5 2001

ISO/AFNOR 1989 Dictionary of computer science - The - -
standardised vocabulary
ISO/IEC 10646-1 1993 Information technology - Universal - -
Multiple-Octet Coded Character set
(UCS) - Part 1: Architecture and Basic
Multilingual Plane
1)
Undated reference.
2)
Valid editon at date of issue.

IEC 61131-3
Edition 2.0 2003-01
INTERNATIONAL
STANDARD
Programmable controllers –
Part 3: Programming languages
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XK
ICS 25.040; 35.240.50 ISBN 2-8318-6653-7

– 2 – 61131-3 ” IEC:2003(E)
CONTENTS
FOREWORD .8
1 General.9
1.1 Scope.9
1.2 Normative references .9
1.3 Definitions.9
1.4 Overview and general requirements .14
1.4.1 Software model.14
1.4.2 Communication model.16
1.4.3 Programming model .18
1.5 Compliance.19
1.5.1 System compliance .20
1.5.2 Program compliance.22
2 Common elements .23
2.1 Use of printed characters .23
2.1.1 Character set .23
2.1.2 Identifiers .23
2.1.3 Keywords.24
2.1.4 Use of white space .24
2.1.5 Comments .24
2.1.6 Pragmas .25
2.2 External representation of data .25
2.2.1 Numeric literals.25
2.2.2 Character string literals .26
2.2.3 Time literals .28
2.2.3.1 Duration .28
2.2.3.2 Time of day and date.29
2.3 Data types .29
2.3.1 Elementary data types.30
2.3.2 Generic data types .31
2.3.3 Derived data types.32
2.3.3.1 Declaration .32
2.3.3.2 Initialization.33
2.3.3.3 Usage .35
2.4 Variables.36
2.4.1 Representation .36
2.4.1.1 Single-element variables .36
2.4.1.2 Multi-element variables .38
2.4.2 Initialization.38
2.4.3 Declaration .39
2.4.3.1 Type assignment .41
2.4.3.2 Initial value assignment.42
2.5 Program organization units .45
2.5.1 Functions .45
2.5.1.1 Representation .46
2.5.1.2 Execution control.49
2.5.1.3 Declaration .50
2.5.1.4 Typing, overloading, and type conversion.52
2.5.1.5 Standard functions.55
2.5.1.5.1 Type conversion functions.55
2.5.1.5.2 Numerical functions.56
2.5.1.5.3 Bit string functions .59
2.5.1.5.4 Selection and comparison functions.59
2.5.1.5.5 Character string functions .62
2.5.1.5.6 Functions of time data types .64
2.5.1.5.7 Functions of enumerated data types.66

61131-3 ” IEC:2003(E) – 3 –
2.5.2 Function blocks.66
2.5.2.1 Representation .67
2.5.2.1a) Use of EN and ENO in function blocks .68
2.5.2.2 Declaration .69
2.5.2.3 Standard function blocks.77
2.5.2.3.1 Bistable elements .77
2.5.2.3.2 Edge detection.78
2.5.2.3.3 Counters .78
2.5.2.3.4 Timers.81
2.5.2.3.5 Communication function blocks.83
2.5.3 Programs.83
2.6 Sequential Function Chart (SFC) elements.84
2.6.1 General.84
2.6.2 Steps.84
2.6.3 Transitions .86
2.6.4 Actions.89
2.6.4.1 Declaration .89
2.6.4.2 Association with steps .91
2.6.4.3 Action blocks .92
2.6.4.4 Action qualifiers .93
2.6.4.5 Action control.94
2.6.5 Rules of evolution.99
2.6.6 Compatibility of SFC elements.107
2.6.7 SFC Compliance requirements .108
2.7 Configuration elements.108
2.7.1 Configurations, resources, and access paths .110
2.7.2 Tasks .114
3 Textual languages .123
3.1 Common elements .123
3.2 Instruction list (IL) .123
3.2.1 Instructions .123
3.2.2 Operators, modifiers and operands.124
3.2.3 Functions and function blocks.126
3.3 Structured Text (ST).129
3.3.1 Expressions .129
3.3.2 Statements .131
3.3.2.1 Assignment statements .133
3.3.2.2 Function and function block control statements.133
3.3.2.3 Selection statements .133
3.3.2.4 Iteration statements.134
4 Graphic languages .135
4.1 Common elements .135
4.1.1 Representation of lines and blocks .135
4.1.2 Direction of flow in networks.135
4.1.3 Evaluation of networks .136
4.1.4 Execution control elements .138
4.2 Ladder diagram (LD) .139
4.2.1 Power rails.139
4.2.2 Link elements and states.139
4.2.3 Contacts .140
4.2.4 Coils.140
4.2.5 Functions and function blocks.140
4.2.6 Order of network evaluation .141
4.3 Function Block Diagram (FBD).143
4.3.1 General.143
4.3.2 Combination of elements.143
4.3.3 Order of network evaluation .143

– 4 – 61131-3 ” IEC:2003(E)
ANNEX A (normative) Specification method for textual languages .144
A.1 Syntax .144
A.1.1  Terminal symbols.144
A.1.2  Non-terminal symbols .144
A.1.3  Production rules .145
A.2 Semantics .145
ANNEX B (normative) Formal specifications of language elements.146
B.0 Programming model.146
B.1 Common elements.146
B.1.1 Letters, digits and identifiers .146
B.1.2 Constants .147
B.1.2.1  Numeric literals .147
B.1.2.2 Character strings.147
B.1.2.3 Time literals.148
B.1.2.3.1 Duration.148
B.1.2.3.2 Time of day and date .148
B.1.3  Data types .149
B.1.3.1 Elementary data types .149
B.1.3.2 Generic data types.149
B.1.3.3 Derived data types .149
B.1.4 Variables .151
B.1.4.1 Directly represented variables .151
B.1.4.2 Multi-element variables .151
B.1.4.3 Declaration and initialization .152
B.1.5 Program organization units .154
B.1.5.1 Functions.154
B.1.5.2 Function blocks .155
B.1.5.3 Programs.156
B.1.6 Sequential function chart elements.156
B.1.7 Configuration elements .157
B.2 Language IL (Instruction List) .159
B.2.1 Instructions and operands.159
B.2.2 Operators .159
B.3 Language ST (Structured Text) .160
B.3.1 Expressions.160
B.3.2 Statements .160
B.3.2.1 Assignment statements.161
B.3.2.2 Subprogram control statements.161
B.3.2.3 Selection statements.161
B.3.2.4 Iteration statements.161
ANNEX C (normative) Delimiters and keywords.162
ANNEX D (normative) Implementation-dependent parameters.165
ANNEX E (normative) Error conditions .167
ANNEX F (informative) Examples .169
F.1 Function WEIGH .169
F.2 Function block CMD_MONITOR.170
F.3 Function block FWD_REV_MON .173
F.4 Function block STACK_INT.178
F.5 Function block MIX_2_BRIX .183
F.6 Analog signal processing .186
F.6.1 Function block LAG1 .187
F.6.2 Function block DELAY .187

61131-3 ” IEC:2003(E) – 5 –
F.6.3 Function block AVERAGE.188
F.6.4 Function block INTEGRAL.188
F.6.5 Function block DERIVATIVE .189
F.6.6 Function block HYSTERESIS .189
F.6.7 Function block LIMITS_ALARM .190
F.6.8 Structure ANALOG_LIMITS.190
F.6.9 Function block ANALOG_MONITOR.191
F.6.10 Function block PID.192
F.6.11 Function block DIFFEQ .193
F.6.12 Function block RAMP .194
F.6.13 Function block TRANSFER.195
F.7 Program GRAVEL.195
F.8 Program AGV .203
F.9 Use of enumerated data types .206
F.10 Function block RTC (Real Time Clock).206
F.11 Function block ALRM_INT.206
ANNEX G (informative) Reference character set.208
Index .210
Table 1 - Character set features.23
Table 2 - Identifier features.24
Table 3 - Comment feature.25
Table 3a - Pragma feature.25
Table 4 - Numeric literals.26
Table 5 - Character string literal features.27
Table 6 - Two-character combinations in character strings .28
Table 7 - Duration literal features .29
Table 8 - Date and time of day literals.29
Table 9 - Examples of date and time of day literals .29
Table 10 - Elementary data types .30
Table 11 - Hierarchy of generic data types .32
Table 12 - Data type declaration features .33
Table 13 - Default initial values of elementary data types.34
Table 14 - Data type initial value declaration features .35
Table 15 - Location and size prefix features for directly represented variables.37
Table 16a - Variable declaration keywords .39
Table 16b - Usages of VAR_GLOBAL, VAR_EXTERNAL and CONSTANT declarations .41
Table 17 - Variable type assignment features.41
Table 18 - Variable initial value assignment features.43
Table 19 - Graphical negation of Boolean signals .47
Table 19a - Textual invocation of functions for formal and non-formal argument list .49
Table 20 - Use of EN input and ENO output .50
Table 20a - Function features.51
Table 21 - Typed and overloaded functions.53
Table 22 - Type conversion function features .55
Table 23 - Standard functions of one numeric variable.57
Table 24 - Standard arithmetic functions.58

– 6 – 61131-3 ” IEC:2003(E)
Table 25 - Standard bit shift functions.59
Table 26 - Standard bitwise Boolean functions.60
d
Table 27 - Standard selection functions .61
Table 28 - Standard comparison functions.62
Table 29 - Standard character string functions .63
Table 30 - Functions of time data types .64
Table 31 - Functions of enumerated data types.66
Table 32 - Examples of function block I/O variable usage .68
Table 33 - Function block declaration and usage features .71
a
Table 34 - Standard bistable function blocks .77
Table 35 - Standard edge detection function blocks.78
Table 36 - Standard counter function blocks.79
Table 37 - Standard timer function blocks.81
Table 38 - Standard timer function blocks - timing diagrams.82
Table 39 - Program declaration features.83
Table 40 - Step features.85
Table 41 - Transitions and transition conditions.87
a,b
Table 42 - Declaration of actions .90
Table 43 - Step/action association .92
Table 44 - Action block features.93
Table 45 - Action qualifiers.94
Table 45a - Action control features .98
Table 46 - Sequence evolution.101
Table 47 - Compatible SFC features.108
Table 48 - SFC minimal compliance requirements .108
Table 49 - Configuration and resource declaration features.112
Table 50 - Task features.116
Table 51a - Examples of instruction fields.124
Table 51b - Parenthesized expression features for IL language.125
Table 52 - Instruction List operators.125
Table 53 - Function Block invocation and Function invocation features for IL language.127
Table 54 - Standard Function Block input operators for IL language.129
Table 55 - Operators of the ST language.131
Table 56 - ST language statements .132
Table 57 - Representation of lines and blocks .136
Table 58 - Graphic execution control elements.138
Table 59 - Power rails.139
Table 60 - Link elements .140
a
Table 61 - Contacts .141
Table 62 - Coils .142
Table C.1 - Delimiters.162
Table C.2 - Keywords.163
Table D.1 - Implementation-dependent parameters .165
Table E.1 - Error conditions.167

61131-3 ” IEC:2003(E) – 7 –
Table G.1 - Character representations.208
Table G.2 - Character encodings .209
Figure 1 - Software model .15
Figure 2 a) - Data flow connection within a program.16
Figure 2 b) - Communication via GLOBAL variables.16
Figure 2 c) - Communication function blocks .17
Figure 2 d) - Communication via access paths .17
Figure 3 - Combination of programmable controller language elements .19
Figure 4 - Examples of function usage.45
Figure 5 - Use of formal argument names.48
Figure 6 - Examples of function declarations and usage .52
Figure 7 - Examples of explicit type conversion with overloaded functions .54
Figure 8 - Examples of explicit type conversion with typed functions .54
Figure 9 - Function block instantiation examples .67
Figure 10 - Examples of function block declarations.70
Figure 11 a) - Graphical use of a function block name as an input variable .73
Figure 11 b) - Graphical use of a function block name as an in-out variable.74
Figure 11 c) - Graphical use of a function block name as an external variable .75
Figure 12 - Declaration and usage of in-out variables in function blocks.76
Figure 14 - ACTION_CONTROL function block - External interface (Not visible to the user) .95
Figure 15 a) - ACTION_CONTROL function block body with “final scan” logic.96
Figure 15 b) - ACTION_CONTROL function block body without “final scan” logic.97
Figure 16 a) - Action control example - SFC representation.98
Figure 16 b) - Action control example - functional equivalent .99
Figure 17 - Examples of SFC evolution rules.105
Figure 18 a) - Examples of SFC errors: an “unsafe” SFC.106
Figure 18 b) - Examples of SFC errors: an “unreachable” SFC.107
Figure 19 a) - Graphical example of a configuration .109
Figure 19 b) - Skeleton function block and program declarations for configuration example .110
Figure 20 - Examples of CONFIGURATION and RESOURCE declaration features.113
Figure 21 a) - Synchronization of function blocks with explicit task associations .120
Figure 21 b) - Synchronization of function blocks with implicit task associations .121
Figure 21 c) - Explicit task associations equivalent to figure 21 b) .122
Figure 22 - EXIT statement example.134
Figure 23 - Feedback path example.137
Figure 24 - Boolean OR examples .143

– 8 – 61131-3 ” IEC:2003(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PROGRAMMABLE CONTROLLERS –
Part 3: Programming languages
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical comm
...