Mitsubishi Electric MELSEC Q Series Owner's manual

MELSEC-Q/L/F Structured
Programming Manual (Fundamentals)

1
SAFETY PRECAUTIONS
(Read these precautions before using this product.)
Before using MELSEC-Q, -L, or -F series programmable controllers, please read the manuals included with each product and
the relevant manuals introduced in those manuals carefully, and pay full attention to safety to handle the product correctly.
Make sure that the end users read the manuals included with each product, and keep the manuals in a safe place for future
reference.
CONDITIONS OF USE FOR THE PRODUCT
(1) Mitsubishi programmable controller ("the PRODUCT") shall be used in conditions;
i) where any problem, fault or failure occurring in the PRODUCT, if any, shall not lead to any major or serious accident;
and
ii) where the backup and fail-safe function are systematically or automatically provided outside of the PRODUCT for the
case of any problem, fault or failure occurring in the PRODUCT.
(2) The PRODUCT has been designed and manufactured for the purpose of being used in general industries.
MITSUBISHI SHALL HAVE NO RESPONSIBILITY OR LIABILITY (INCLUDING, BUT NOT LIMITED TO ANY AND ALL
RESPONSIBILITY OR LIABILITY BASED ON CONTRACT, WARRANTY, TORT, PRODUCT LIABILITY) FOR ANY
INJURY OR DEATH TO PERSONS OR LOSS OR DAMAGE TO PROPERTY CAUSED BY the PRODUCT THAT ARE
OPERATED OR USED IN APPLICATION NOT INTENDED OR EXCLUDED BY INSTRUCTIONS, PRECAUTIONS, OR
WARNING CONTAINED IN MITSUBISHI'S USER, INSTRUCTION AND/OR SAFETY MANUALS, TECHNICAL
BULLETINS AND GUIDELINES FOR the PRODUCT.
("Prohibited Application")
Prohibited Applications include, but not limited to, the use of the PRODUCT in;
• Nuclear Power Plants and any other power plants operated by Power companies, and/or any other cases in which the
public could be affected if any problem or fault occurs in the PRODUCT.
• Railway companies or Public service purposes, and/or any other cases in which establishment of a special quality
assurance system is required by the Purchaser or End User.
• Aircraft or Aerospace, Medical applications, Train equipment, transport equipment such as Elevator and Escalator,
Incineration and Fuel devices, Vehicles, Manned transportation, Equipment for Recreation and Amusement, and
Safety devices, handling of Nuclear or Hazardous Materials or Chemicals, Mining and Drilling, and/or other
applications where there is a significant risk of injury to the public or property.
Notwithstanding the above restrictions, Mitsubishi may in its sole discretion, authorize use of the PRODUCT in one or
more of the Prohibited Applications, provided that the usage of the PRODUCT is limited only for the specific
applications agreed to by Mitsubishi and provided further that no special quality assurance or fail-safe, redundant or
other safety features which exceed the general specifications of the PRODUCTs are required. For details, please
contact the Mitsubishi representative in your region.

2
INTRODUCTION
Thank you for purchasing the Mitsubishi Electric MELSEC-Q, -L, or -F series programmable controllers.
Before using this product, please read this manual and the relevant manuals carefully and develop familiarity with the
programming specifications to handle the product correctly.
When applying the program examples introduced in this manual to an actual system, ensure the applicability and confirm that
it will not cause system control problems.
Applicable CPU modules
Compatible software package
The following programming tool is used for creating, editing, and monitoring the programs in the Structured project.
■What is GX Works2?
GX Works2 is a software package used for editing and debugging sequence programs, monitoring programmable controller
CPUs, and other operations. It runs on a personal computer in the MicrosoftWindowsOperating System environment.
Created sequence programs are managed in units of 'projects' for each programmable controller CPU. Projects are broadly
divided into 'Simple project' and 'Structured project'.
This manual explains the basic programming by referring the Structured project in GX Works2.
CPU module Model
Basic model QCPU Q00JCPU, Q00CPU, Q01CPU
High Performance model QCPU Q02CPU, Q02HCPU, Q06HCPU, Q12HCPU, Q25HCPU
Process CPU Q02PHCPU, Q06PHCPU, Q12PHCPU, Q25PHCPU
Redundant CPU Q12PRHCPU, Q25PRHCPU
Universal model QCPU Q00UJCPU, Q00UCPU, Q01UCPU, Q02UCPU, Q03UDCPU, Q03UDVCPU, Q03UDECPU,
Q04UDHCPU, Q04UDVCPU, Q04UDPVCPU, Q04UDEHCPU, Q06UDHCPU, Q06UDVCPU,
Q06UDPVCPU, Q06UDEHCPU, Q10UDHCPU, Q10UDEHCPU, Q13UDHCPU, Q13UDVCPU,
Q13UDPVCPU, Q13UDEHCPU, Q20UDHCPU, Q20UDEHCPU, Q26UDHCPU, Q26UDVCPU,
Q26UDPVCPU, Q26UDEHCPU, Q50UDEHCPU, Q100UDEHCPU
LCPU L02SCPU, L02SCPU-P, L02CPU, L02CPU-P, L06CPU, L06CPU-P, L26CPU, L26CPU-P, L26CPU-BT,
L26CPU-PBT
FXCPU FX0S, FX0, FX0N, FX1S, FX1N, FX1NC, FX2, FX2C, FX2N, FX2NC, FX3S, FX3G, FX3GC, FX3U, FX3UC
Software package name Model name
GX Works2 SW1DNC-GXW2-E, SW1DND-GXW2-E

3
MEMO

4
CONTENTS
SAFETY PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
CONDITIONS OF USE FOR THE PRODUCT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
MANUALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
TERMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
CHAPTER 1 OVERVIEW 8
1.1 Purpose of This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.2 Features of Structured Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
CHAPTER 2 STRUCTURED DESIGN OF SEQUENCE PROGRAMS 11
2.1 Hierarchical Sequence Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.2 Structured Sequence Program. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
CHAPTER 3 PROCEDURE FOR CREATING PROGRAMS 13
CHAPTER 4 PROGRAM CONFIGURATION 15
4.1 Overview of Program Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Program files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.2 POUs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Types of POU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Program. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Function blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Operators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Ladder blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Programming languages for POUs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Functions, function blocks, and operators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
EN and ENO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
4.3 Labels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Global labels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Local labels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Label classes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Setting labels. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Data types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Expressing methods of constants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.4 Method for Specifying Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Bit data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Word (16 bits) data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Double word (32 bits) data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Single-precision real/double-precision real data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
String data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Time data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
4.5 Device and Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

5
CONTENTS
Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Correspondence between devices and addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
4.6 Index Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
4.7 Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
User libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
4.8 Precautions on Assigning a Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
CHAPTER 5 WRITING PROGRAMS 73
5.1 ST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Standard format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Operators in ST language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Syntax in ST language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Calling functions in ST language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Calling function blocks in ST language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Precautions when using conditional syntax and iteration syntax. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Operations when the master control instruction is used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
5.2 Structured Ladder/FBD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Standard format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Ladder symbols in structured ladder/FBD language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Executing order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Ladder branches and compilation results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Precautions on creating programs with structured ladder/FBD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
APPENDICES 93
Appendix 1 Correspondence Between Generic Data Types and Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Internal user device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Internal system device. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Link direct device. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Intelligent function module device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Index register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
File register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Nesting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Constant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
String constant. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Appendix 2 Character Strings That Cannot Be Used in Label Names and Data Names . . . . . . . . . . . . . . . . . . . 100
Appendix 3 Recreating Ladder Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Procedure for creating a structured program. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Example of creating a structured program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
INDEX 108
REVISIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
WARRANTY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
TRADEMARKS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

6
MANUALS
Related Manuals
The manuals related to this product are listed below. Please place an order as needed.
■Structured programming
■Operation of GX Works2
Manual name
<Manual number>
Description
MELSEC-Q/L Structured Programming Manual (Common
Instructions)
<SH-080783ENG>
Specifications and functions of common instructions, such as sequence instructions, basic
instructions, and application instructions, that can be used in structured programs
MELSEC-Q/L Structured Programming Manual (Application
Functions)
<SH-080784ENG>
Specifications and functions of application functions that can be used in structured programs
MELSEC-Q/L Structured Programming Manual (Special
Instructions)
<SH-080785ENG>
Specifications and functions of special instructions, such as module dedicated instructions,
PID control instructions, and built-in I/O function instructions, that can be used in structured
programs
FXCPU Structured Programming Manual [Device & Common]
<JY997D26001>
Devices and parameters for structured programming provided in GX Works2
FXCPU Structured Programming Manual [Basic & Applied
Instruction]
<JY997D34701>
Sequence instructions for structured programming provided in GX Works2
FXCPU Structured Programming Manual [Application
Functions]
<JY997D34801>
Application functions for structured programming provided in GX Works2
Manual name
<Manual number>
Description
GX Works2 Version 1 Operating Manual (Common)
<SH-080779ENG>
System configuration, parameter settings, and online operations of GX Works2, which are
common to Simple projects and Structured projects
GX Works2 Version 1 Operating Manual (Structured Project)
<SH-080781ENG>
Operations, such as programming and monitoring in Structured projects, of GX Works2
GX Works2 Beginner's Manual (Structured Project)
<SH-080788ENG>
Basic operations, such as programming, editing, and monitoring in Structured projects, of GX
Works2. This manual is intended for first-time users of GX Works2.

7
TERMS
This manual uses the generic terms and abbreviations listed in the following table to discuss the software packages and
programmable controller CPUs. Corresponding module models are also listed if needed.
Term Description
Application function A generic term for the functions, such as functions and function blocks, defined in IEC 61131-3.
(The functions are executed with a set of common instructions in a programmable controller.)
Basic model QCPU A generic term for the Q00JCPU, Q00CPU, and Q01CPU
Common instruction A generic term for the sequence instructions, basic instructions, application instructions, data link instructions,
multiple CPU dedicated instructions, multiple CPU high-speed transmission dedicated instructions, and
redundant system instructions
CPU module A generic term for the QCPU (Q mode), LCPU, and FXCPU
FXCPU A generic term for MELSEC-FX series programmable controllers
(FX0S, FX0, FX0N, FX1, FX1S, FX1N, FX1NC, FX2, FX2C, FX2N, FX2NC, FX3S, FX3G, FX3GC, FX3U, FX3UC)
GX Developer The product name of the software package for the MELSEC programmable controllers
GX Works2
High Performance model QCPU A generic term for the Q02CPU, Q02HCPU, Q06HCPU, Q12HCPU, and Q25HCPU
High-speed Universal model QCPU A generic term for the Q03UDVCPU, Q04UDVCPU, Q06UDVCPU, Q13UDVCPU, and Q26UDVCPU
IEC 61131-3 An abbreviation for the IEC 61131-3 international standard
LCPU A generic term for the L02SCPU, L02SCPU-P, L02CPU, L02CPU-P, L06CPU, L06CPU-P, L26CPU, L26CPU-P,
L26CPU-BT, and L26CPU-PBT
Personal computer The generic term for personal computers where Windowsoperates
Process CPU A generic term for the Q02PHCPU, Q06PHCPU, Q12PHCPU, and Q25PHCPU
QCPU (Q mode) A generic term for the Basic model QCPU, High Performance model QCPU, Process CPU, Redundant CPU,
and Universal model QCPU
QnU(D)(H)CPU A generic term for the Q02UCPU, Q03UDCPU, Q04UDHCPU, Q06UDHCPU, Q10UDHCPU, Q13UDHCPU,
Q20UDHCPU, and Q26UDHCPU
QnUDE(H)CPU A generic term for the Q03UDECPU, Q04UDEHCPU, Q06UDEHCPU, Q10UDEHCPU, Q13UDEHCPU,
Q20UDEHCPU, Q26UDEHCPU, Q50UDEHCPU, and Q100UDEHCPU
QnUDPVCPU A generic term for the Q04UDPVCPU, Q06UDPVCPU, Q13UDPVCPU, and Q26UDPVCPU
QnUDVCPU A generic term for the Q03UDVCPU, Q04UDVCPU, Q06UDVCPU, Q13UDVCPU, and Q26UDVCPU
Redundant CPU A generic term for the Q12PRHCPU and Q25PRHCPU
Special instruction A generic term for the module dedicated instructions, PID control instructions, socket communication function
instructions, built-in I/O function instructions, and data logging function instructions
Universal model Process CPU A generic term for the Q04UDPVCPU, Q06UDPVCPU, Q13UDPVCPU, and Q26UDPVCPU
Universal model QCPU A generic term for the Q00UJCPU, Q00UCPU, Q01UCPU, Q02UCPU, Q03UDCPU, Q03UDVCPU,
Q03UDECPU, Q04UDHCPU, Q04UDVCPU, Q04UDPVCPU, Q04UDEHCPU, Q06UDHCPU, Q06UDVCPU,
Q06UDPVCPU, Q06UDEHCPU, Q10UDHCPU, Q10UDEHCPU, Q13UDHCPU, Q13UDVCPU,
Q13UDPVCPU, Q13UDEHCPU, Q20UDHCPU, Q20UDEHCPU, Q26UDHCPU, Q26UDVCPU,
Q26UDPVCPU, Q26UDEHCPU, Q50UDEHCPU, and Q100UDEHCPU

81 OVERVIEW
1.1 Purpose of This Manual
1OVERVIEW
This manual describes program configurations and content for creating sequence programs using a structured programming
method, and provides basic knowledge for writing programs.
1.1 Purpose of This Manual
This manual explains programming methods, programming languages, and other information necessary for creating
structured programs. Manuals for reference are listed in the following table according to their purpose.
For information such as the contents and number of each manual, refer to the following.
Page 6 Related Manuals
Operation of GX Works2
Operations in each programming language
For details of instructions used in each programming language, refer to the following.
Page 9 Details of instructions in each programming language
*1 MELSAP3 and FX series SFC only
Purpose Summary Detail
Installation Learning the operating environment
and installation method
GX Works2 Installation Instructions
Learning a USB driver installation
method
GX Works2 Version 1 Operating Manual
(Common)
Operation of GX
Works2
Learning all functions of GX Works2 GX Works2 Version 1 Operating Manual
(Common)

Learning the project types and
available languages in GX Works2

Learning the basic operations and
operating procedures when creating a
simple project for the first time
GX Works2 Beginner's Manual (Simple
Project)
Learning the basic operations and
operating procedures when creating a
structured project for the first time
GX Works2 Beginner's Manual
(Structured Project)
Learning the operations of available
functions regardless of project type.
GX Works2 Version 1 Operating Manual
(Common)
Learning the functions and operation
methods for programming
GX Works2 Version 1 Operating Manual
(Common)
GX Works2 Version 1 Operating Manual
(Simple Project)
GX Works2 Version 1 Operating Manual
(Structured Project)
Learning data setting methods for
intelligent function module
GX Works2 Version 1 Operating Manual
(Intelligent Function Module)
Purpose Summary Detail
Simple Project Ladder GX Works2 Beginner's Manual (Simple
Project)
GX Works2 Version 1 Operating Manual
(Simple Project)
SFC GX Works2 Beginner's Manual (Simple
Project)*1
ST GX Works2 Beginner's Manual
(Structured Project)
GX Works2 Version 1 Operating Manual
(Structured Project)
Structured Project Ladder GX Works2 Beginner's Manual (Simple
Project)
GX Works2 Version 1 Operating Manual
(Simple Project)
SFC GX Works2 Beginner's Manual (Simple
Project)*1
Structured ladder/FBD GX Works2 Beginner's Manual
(Structured Project)
GX Works2 Version 1 Operating Manual
(Structured Project)
ST

1 OVERVIEW
1.1 Purpose of This Manual 9
1
Details of instructions in each programming language
■QCPU (Q mode)/LCPU
■FXCPU
Purpose Summary Detail
All languages Learning details of programmable
controller CPU error codes, special
relay areas, and special register areas
User's Manual (Hardware Design,
Maintenance and Inspection) for the CPU
module used
Using ladder
language
Learning the types and details of
common instructions
MELSEC-Q/L Programming Manual
(Common Instruction)
Learning the types and details of
instructions for intelligent function
modules
Manual for the intelligent function module
used
Learning the types and details of
instructions for network modules
Manual for the network module used
Learning the types and details of
instructions for the PID control function
MELSEC-Q/L/QnA Programming Manual
(PID Control Instructions)
Learning the types and details of the
process control instructions
MELSEC-Q Programming/Structured
Programming Manual (Process Control
Instructions)
Using SFC
language
Learning details of specifications,
functions, and instructions of SFC
(MELSAP3)
MELSEC-Q/L/QnA Programming Manual
(SFC)
Using structured
ladder/FBD/ST
language
Learning the fundamentals for creating
a structured program
MELSEC-Q/L/F Structured Programming
Manual (Fundamentals)
Learning the types and details of
common instructions
MELSEC-Q/L Structured Programming
Manual (Common Instructions)
Learning the types and details of
instructions for intelligent function
modules
MELSEC-Q/L Structured Programming
Manual (Special Instructions)
Manual for the intelligent function module
used
Learning the types and details of
instructions for network modules
Manual for the network module used
Learning the types and details of
instructions for the PID control function
MELSEC-Q/L/QnA Programming Manual
(PID Control Instructions)
Learning the types and details of
application functions
MELSEC-Q/L Structured Programming
Manual (Application Functions)
Learning the types and details of the
process control instructions
MELSEC-Q Programming/Structured
Programming Manual (Process Control
Instructions)
Purpose Summary Detail
Using ladder
language
Learning the types and details of basic/
application instructions, descriptions of
devices and parameters
Programming manual for the FXCPU
used
Using SFC
language
Learning details of specifications,
functions, and instructions of SFC

Using structured
ladder/FBD/ST
language
Learning the fundamentals for creating
a structured program
MELSEC-Q/L/F Structured Programming
Manual (Fundamentals)
Learning the descriptions of devices,
parameters, and error codes
FXCPU Structured Programming Manual
[Device & Common]
Learning the types and details of
sequence instructions
FXCPU Structured Programming Manual
[Basic & Applied Instruction]
Learning the types and details of
application functions
FXCPU Structured Programming Manual
[Application Functions]

10 1 OVERVIEW
1.2 Features of Structured Programs
1.2 Features of Structured Programs
This section explains the features of structured programs.
Structured design
A structured design is a method to program control content performed by a programmable controller CPU, which are divided
into small processing units (components) to create hierarchical structures. A user can design programs knowing the
component structures of sequence programs by using the structured programming.
The following are the advantages of creating hierarchical programs.
• A user can start programming by planning the outline of a program, then gradually work into detailed designs.
• Programs stated at the lowest level of a hierarchical design are extremely simple and each program has a high degree of
independence.
The following are the advantages of creating structured programs.
• The process of each component is clarified, allowing a good perspective of the program.
• Programs can be divided and created by multiple programmers.
• Program reusability is increased, and it improves the efficiency in development.
Multiple programming languages
Multiple programming languages are available for structured programs. A user can select the most appropriate programming
language for each purpose, and combine them for creating programs. Different programming language can be used for each
POU.
For outlines of the programming languages, refer to the following section.
Page 23 Programming languages for POUs
For details on each programming language, refer to the following chapter.
Page 73 WRITING PROGRAMS
The ladder/SFC languages used in the existing GX Developer and Simple projects of GX Works2 can be used.
For details on writing programs, refer to the following manuals.
Programming manuals for each CPU
Improved program reusability
Program components can be stored as libraries. This means program assets can be utilized to improve the reusability of
programs.
Name Description
ST (structured text) A text language similar to C language, aimed for computer engineers.
Structured ladder/FBD Structured ladder A graphic language that is expressed in form of ladder by using elements such as contacts
and coils.
FBD A graphic language that is expressed in form of ladder by connecting elements such as
functions and function blocks with lines.

2 STRUCTURED DESIGN OF SEQUENCE PROGRAMS
2.1 Hierarchical Sequence Program 11
2
2STRUCTURED DESIGN OF SEQUENCE
PROGRAMS
2.1 Hierarchical Sequence Program
The hierarchy is to create a sequence program by dividing control functions performed in a programmable controller CPU into
a number of levels.
In higher levels, the processing order and timing in a fixed range is controlled. With each move from a higher level to a lower
level, control content and processes are progressively subdivided within a fixed range, and specific processes are described
in lower levels.
In the Structured project, hierarchical sequence programs are created with the configuration that states the highest level as
the project, followed by program files, tasks, and POUs (abbreviation for Program Organization Units).
Project
POUs
Task (Initialization)
Initial process
Lamp test
Program file (Operation preparation)
Task (Station A control)
Conveyor drive A
Data process A
Program file (Station A)
Task (Station B control)
Task (Indicator control)
Conveyor drive B
Data process B
Indicator output
Program file (Station B)
Initial process
Lamp test
Conveyor drive A
Conveyor drive B
Data process A
Data process B
Indicator output

12 2 STRUCTURED DESIGN OF SEQUENCE PROGRAMS
2.2 Structured Sequence Program
2.2 Structured Sequence Program
A structured program is a program created by components. Processes in lower levels of hierarchical sequence program are
divided to several components according to their processing information and functions.
In a structured program design, segmenting processes in lower levels as much as possible is recommended. Each
component is designed to have a high degree of independence for easy addition and replacement.
The following shows examples of the process that would be ideal to be structured.
• A process that is used repeatedly in a sequence program.
• A process that can be divided into components.
Aprocess that isused repeatedlyinasequence program
Control content in
aprogrammablecontroller CPU
Control content in
aprogrammablecontroller CPU
CallsProcess A
CallsProcess A
CallsProcess A
DIV
MUL
DIV
MUL
DIV
DIV
MUL
MUL
Process A
Structured
program
Divided
Divided
Control 1
Control a
Structured
program
Control b
Control c
Control d
Control 2
Aprocess that can bedivided into components
Control
content
ina
programmable
controller
CPU
Divided

3 PROCEDURE FOR CREATING PROGRAMS
13
3
3PROCEDURE FOR CREATING PROGRAMS
This section explains the basic procedure for creating a sequence program in the Structured project.
1. Creating the program configuration
• Create program files.
• Create tasks.
2. Creating POUs
•CreatePOUs.
• Define global labels.
• Define local labels.
• Edit the programs of each POU.
3. Setting the programs
Register the POUs in the tasks.
4. Compiling the programs
Compile the programs.
Creating theprogram
configuration Creating POUs Setting theprograms Compiling
theprograms
Program file POU
Task 1
Task 2
Program file
Task 1
Task 2
Program 1
Program 2
Program 3
Program 4
Function block 1
Function block 2
Function 1
Function 2
Sequence
program
Program 1
Program 2
Program 3
Program 4

14 3 PROCEDURE FOR CREATING PROGRAMS
MEMO

4 PROGRAM CONFIGURATION
4.1 Overview of Program Configuration 15
4
4PROGRAM CONFIGURATION
4.1 Overview of Program Configuration
A sequence program created in the Structured project is composed of program files, tasks, and POUs.
For details of program components, refer to the following sections.
The following figure shows the configuration of program files, tasks, and POUs in the project.
Item Reference
Projects Page 16 Project
Program files Page 16 Program files
Tasks Page 17 Tasks
POUs Page 18 POUs
Project
Program file2
POU
Program
POU
Program
POU
Program
Task
Program file1
POU
Program
POU
Program
Task
POU
Program
POU
Program
Task
Program filen
POU
Program
POU
Program
Task
POU
Program
Task

16 4 PROGRAM CONFIGURATION
4.1 Overview of Program Configuration
Project
A project is a generic term for data (such as programs and parameters) to be executed in a programmable controller CPU.
One or more program files need to be created in a project.
Program files
One or more tasks need to be created in a program file. (Created tasks are executed under the control of the program file.)
The execution types (such as scan execution and fixed scan execution) for executing program files in a programmable
controller CPU are set in the program setting of the parameter.
For details of the execution types set in the parameter, refer to the user's manual for the CPU module used.
Program file2Program file2Program file1Program file1 Program filenProgram filen
Project
Program file2
POU
Program
POU
Program
POU
Program
Task
Program file1
POU
Program
POU
Program
Task
POU
Program
POU
Program
Task
Program filen
POU
Program
POU
Program
Task
POU
Program
Task

4 PROGRAM CONFIGURATION
4.1 Overview of Program Configuration 17
4
Tasks
A task is an element that contains multiple POUs, and it is registered to a program file. One or more programs of POU need to
be registered in a task. (Functions and function blocks cannot be registered in a task.)
Task executing condition
The executing conditions in a programmable controller CPU are set for each task that is registered to program files. Executing
processes are determined for each task by setting the executing condition. The following are the types of task executing
condition.
■Always (Default executing condition)
Executes registered programs for each scan.
■Event
Executes tasks when values are set to the corresponding devices or labels.
■Interval
Executes tasks in a specified cycle.
Priority
A priority can be set for each task execution.
When executing conditions of multiple tasks are met simultaneously, the tasks are executed according to the set priority.
• Tasks are executed in the order from the smallest priority level number.
• Tasks set with a same priority level number are executed in the order of task data name.
TaskTaskTaskTask
TaskTask
TaskTask
TaskTask
Project
Program file2
POU
Program
POU
Program
POU
Program
Task
Program file1
POU
Program
POU
Program
Task
POU
Program
POU
Program
Task
Program filen
POU
Program
POU
Program
Task
POU
Program
Task

18 4 PROGRAM CONFIGURATION
4.2 POUs
4.2 POUs
A POU (abbreviation for Program Organization Unit) is a program component defined by each function.
Types of POU
The following three types can be selected for each POU according to the content to be defined.
•Program
• Function
• Function block
Each POU consists of a program and local labels*1.
A process can be described in a programming language that suits the control function for each POU.
*1 Local labels are labels that can be used only in programs of declared POUs. For details of local labels, refer to the following section.
Page 29 Local labels
ProjectProject
Program fileProgram file
TaskTask
Project
Program file
Task
POU folder
POU
Program
POU
Program
POU
Function
POU
Function block
Registration