Mitsubishi Electric MELSEC iQ-R Series Owner's manual

MELSEC iQ-R Programming Manual
(Program Design)

1
SAFETY PRECAUTIONS
(Read these precautions before using this product.)
Before using the Mitsubishi Electric MELSEC iQ-R series programmable controllers, please read the manuals for the 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 this manual and then keep the manual 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
• For Safety CPUs
(1) Although MELCO has obtained the certification for Product's compliance to the international safety standards
IEC61508, EN954-1/ISO13849-1 from TUV Rheinland, this fact does not guarantee that Product will be free from any
malfunction or failure. The user of this Product shall comply with any and all applicable safety standard, regulation or
law and take appropriate safety measures for the system in which the Product is installed or used and shall take the
second or third safety measures other than the Product. MELCO is not liable for damages that could have been
prevented by compliance with any applicable safety standard, regulation or law.
(2) MELCO prohibits the use of Products with or in any application involving, and MELCO shall not be liable for a default, a
liability for defect warranty, a quality assurance, negligence or other tort and a product liability in these applications.
(a) power plants,
(b) trains, railway systems, airplanes, airline operations, other transportation systems,
(c) hospitals, medical care, dialysis and life support facilities or equipment,
(d) amusement equipments,
(e) incineration and fuel devices,
(f) handling of nuclear or hazardous materials or chemicals,
(g) mining and drilling,
(h) and other applications where the level of risk to human life, health or property are elevated.

3
INTRODUCTION
Thank you for purchasing the Mitsubishi Electric MELSEC iQ-R series programmable controllers.
This manual describes the program structures and data required for programming.
Before using this product, please read this manual and the relevant manuals carefully and develop familiarity with the
functions and performance of the MELSEC iQ-R series programmable controller to handle the product correctly.
When applying the program examples provided in this manual to an actual system, ensure the applicability and confirm that it
will not cause system control problems.
Please make sure that the end users read this manual.
Most of the information in this manual is described using labels. Devices can be used in the same way as
labels.

4
MEMO

5
CONTENTS
CONTENTS
SAFETY PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
CONDITIONS OF USE FOR THE PRODUCT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
RELEVANT MANUALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
TERMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
CHAPTER 1 OVERVIEW 9
CHAPTER 2 PROGRAM CONFIGURATION 11
CHAPTER 3 PROGRAM ORGANIZATION UNITS 13
3.1 Program Blocks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2 Functions (FUN). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.3 Function Blocks (FB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.4 Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.5 When a Safety Program Is Used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Safety functions (Safety FUN). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Safety function blocks (Safety FB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
CHAPTER 4 LABELS 38
4.1 Label Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.2 Classes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.3 Data Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
4.4 Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4.5 Structures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
4.6 Constants. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
4.7 Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
4.8 When a Safety Program Is Used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Safety label types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Data types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
CHAPTER 5 LADDER DIAGRAM 54
5.1 Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Ladder symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Program execution order. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
5.2 Inline ST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
5.3 Statements and Notes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
CHAPTER 6 STRUCTURED TEXT LANGUAGE 59
6.1 Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Delimiters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Operators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Control statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Constants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Labels and devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

6
CHAPTER 7 FBD/LD 75
7.1 Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Program elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Constant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Labels and devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
7.2 Program Execution Order. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Execution order of program elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
CHAPTER 8 SFC PROGRAM 87
8.1 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
8.2 Structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
Step . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Action. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Transition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
8.3 SFC Control Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
8.4 SFC Information Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
8.5 SFC Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
CPU parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
SFC block setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
8.6 SFC Program Execution Order. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
Whole program processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
SFC program processing sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
8.7 SFC Program Execution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
Starting and stopping the SFC program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
Starting and ending a block. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
Pausing and restarting a block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Activating and deactivating a step. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Behavior when an active step is activated. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Operation when a program is modified . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
Checking SFC program operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
APPENDIX 152
Appendix 1 Operations of when the MC/MCR instructions are used to control EN . . . . . . . . . . . . . . . . . . . . . . 152
INDEX 158
REVISIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .160
WARRANTY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .161
TRADEMARKS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .162

7
RELEVANT MANUALS
e-Manual refers to the Mitsubishi Electric FA electronic book manuals that can be browsed using a dedicated
tool.
e-Manual has the following features:
• Required information can be cross-searched in multiple manuals.
• Other manuals can be accessed from the links in the manual.
• The hardware specifications of each part can be found from the product figures.
• Pages that users often browse can be bookmarked.
• Sample programs can be copied to an engineering tool.
Manual name [manual number] Description Available form
MELSEC iQ-R Programming Manual (Program Design)
[SH-081265ENG] (this manual)
Program specifications ( ladder, ST, FBD/LD, and SFC
programs) and labels
e-Manual
PDF
MELSEC iQ-R Programming Manual (Instructions, Standard Functions/
Function Blocks)
[SH-081266ENG]
Instructions for the CPU module, dedicated instructions for the
intelligent function modules, and standard functions/function
blocks
e-Manual
PDF
MELSEC iQ-R Programming Manual (Process Control Function Blocks)
[SH-081749ENG]
Standard process function blocks, tag access function blocks,
and tag function blocks designed for the process control
e-Manual
PDF
GX Works3 Operating Manual
[SH-081215ENG]
System configuration, parameter settings, and online
operations of GX Works3
e-Manual
PDF

8
TERMS
Unless otherwise specified, this manual uses the following terms.
The following terms are used to explain a safety programmable controller system using the Safety CPU.
Term Description
Buffer memory Memory in an intelligent function module for storing data such as setting values and monitored values.
Buffer memory in a CPU module stores setting values and monitored values of the Ethernet function and data used for
data communications among the CPU modules in a multiple CPU system.
CPU module A generic term for the MELSEC iQ-R series CPU modules
Device A device (X, Y, M, D, or others) in a CPU module
Engineering tool The product name of the software package for the MELSEC programmable controllers
GX Works3 The product name of the software package, SWnDNC-GXW3, for the MELSEC programmable controllers (The 'n'
represents a version.)
I/O module A generic term for the input module, output module, I/O combined module, and interrupt module
Intelligent function module A module that has functions other than input and output, such as an A/D converter module and D/A converter module
Label A label that represents a device in a given character string
Module label A label that represents one of memory areas (I/O signals and buffer memory areas) specific to each module in a given
character string. For the module used, the engineering tool automatically generates this label, which can be used as a
global label.
Multiple CPU system A system where two to four CPU modules separately control I/O modules and intelligent function modules
Network module A generic term for the following modules:
• Ethernet interface module
• CC-Link IE Controller Network module
• Module on CC-Link IE Field Network
• MELSECNET/H network module
• MELSECNET/10 network module
• RnENCPU (network part)
Operand A generic term for the devices, such as source data (s), destination data (d), number of devices (n), and others, used
as parts to configure instructions and functions
POU A unit that configures a program. Units are categorized and provided in accordance with functions. Use of POUs
enables dividing the lower-layer processing in a hierarchical program into some units in accordance with processing or
functions, and creating programs for each unit.
Predefined protocol support function A function of GX Works3.
This function sets protocols appropriate to each external device and reads/writes protocol setting data.
Standard/safety shared label A label that can be used in both standard programs and safety programs. This label is used to pass data between
safety programs and standard programs.
Term Description
Safety control Machine control by safety programs and safety data communications. When an error occurs, the machine in operation
is securely stopped.
Safety communications Communication service that performs send/receive processing in the safety layer of the safety communication protocol
Safety device A device that can be used in safety programs
Safety program A program that performs safety control
Standard CPU A generic term for MELSEC iQ-R series CPU modules (other than Safety CPU) that perform standard control (This
term is used to distinguish from the Safety CPU.)
Standard control Machine control by standard programs and standard data communications. Programmable controllers other than the
safety programmable controller perform only standard control. (This term is used to distinguish from safety control.)
Standard communications Communications other than safety communications, such as cyclic transmission and transient transmission of CC-Link
IE Field Network
Standard device A device (X, Y, M, D, or others) in a CPU module. (Safety devices are excluded.) This device can be used only in
standard programs. (This term is used to distinguish from a safety device.)
Standard program A program that performs sequence control. (Safety programs are excluded.) (This term is used to distinguish from a
safety program.)

1 OVERVIEW
9
1
1OVERVIEW
This manual describes program configurations, contents, and coding methods required for programming.
For information on creating, editing, and monitoring programs using an engineering tool, refer to the following.
GX Works3 Operating Manual
Programming languages
With the MELSEC iQ-R series, an optimal programming language can be selected and used according to the application.
■Ladder diagram (Ladder)
For details, refer to the following.
Page 54 LADDER DIAGRAM
■Structured text language (ST)
For details, refer to the following.
Page 59 STRUCTURED TEXT LANGUAGE
Programming language Description
Ladder diagram (Ladder) A graphic language which describes ladders consisting of contacts and coils.
This language is used to describe logical ladders using symbolized contacts and coils to enable
easy-to-understand sequence control.
Structured text language (ST) A textual language used to describe programs using statements (such as IF) and operators.
Compared with the ladder diagram, this language can describe hard-to-describe operation
processing concisely and legibly, and therefore is suitable for programming complicated
arithmetic operations and comparison operations. Also, as with C, ST language can describe
syntax control such as selective branches with conditional statements and repetitions with
iteration statements, and thus can describe easy-to-understand, concise programs.
Function block diagram/ladder diagram (FBD/LD) A graphic language which describes programs by connecting blocks that perform predefined
processing, variable elements, and constant elements along the flow of data and signals.
This language facilitates programming of DDC (direct digital control) processing which is difficult
to describe in ladder diagram, and improves the productivity of programs.
Sequential function chart (SFC program) SFC is a program description format in which a sequence of control operations is split into a
series of steps to enable a clear expression of each program execution sequence and execution
conditions.

10 1 OVERVIEW
■Function block diagram/ladder diagram (FBD/LD)
For details, refer to the following.
Page 75 FBD/LD
■SFC program
For details, refer to the following.
Page 87 SFC PROGRAM
• Programming in ladder is suitable for users who have knowledge and experience of sequence control and
logical ladders. Programming in ST is suitable for users who have knowledge and experience of C
programming. Programming in FBD/LD is suitable for users who perform process control. SFC program is
suitable for creating program blocks for each actual control of machines and controlling the transition of
each operation.
• Using labels in programs can improve readability of programs, and make it easy to immigrate programs to a
system having a different module configuration.

2 PROGRAM CONFIGURATION
11
2
2PROGRAM CONFIGURATION
Using the engineering tool, multiple programs and program organization units (POUs) can be created.
Programs and POUs can be divided according to processing.
This chapter describes the program configuration.
For POUs, refer to the following.
Page 13 PROGRAM ORGANIZATION UNITS
Project
A project is a group of data (such as programs and parameters) to be executed in a CPU module.
Only one project can be written to a single CPU module.
At least one program file needs to be created in a project.
Program file
A program file is a group of programs and POUs.
A program file consists of at least one program block. (Page 14 Program Blocks)
The following operations are performed in units of program file: changing the program execution type from the fixed scan
execution type to the standby type and writing data to the CPU module.
·
Project
Program file 2
Program block
Program file 1
Program block
Program block
FB/FUN file
Function block
Function block
Function
Function
Function

12 2 PROGRAM CONFIGURATION
MEMO

3 PROGRAM ORGANIZATION UNITS
13
3
3PROGRAM ORGANIZATION UNITS
There are three types of program organization units (POUs).
• Program block
• Function
• Function block
Processing can be described in the programming language that suits the control performed in each POU. Processing can be
described in the ladder diagram, structured text language, or FBD/LD in a function or a function block.
Functions and function blocks are called and executed by program blocks.
A structured program is a program created by components. Processes in lower levels of hierarchical
sequence program are divided into several components according to their processing information and
functions.
Each component of a program is specified to have a high degree of independence for easy addition and
replacement.
The following are the examples of processing that would be ideal to be structured.
• Processing which is used repeatedly in a program
• Processing which can be separated as one function
This chapter describes two types of POUs using labels.
Devices can also be used in the program (worksheet) of each POU. For details on devices, refer to the following.
MELSEC iQ-R CPU Module User's Manual (Application)
Up to 32 worksheets can be created in one POU in the structured text language and FBD/LD.
Set the execution order of multiple worksheets on the "Worksheet Execution Order Setting" window of the
engineering tool. (GX Works3 Operating Manual)
Project
Program file
POU folder
POU
Function block
POU
Program block
POU
POU
Function
Used

14 3 PROGRAM ORGANIZATION UNITS
3.1 Program Blocks
3.1 Program Blocks
A program block is a unit for making up a program.
Multiple program blocks can be created in a program file and executed in the order specified in the program file setting. If the
order is not specified in the program file setting, the program blocks are executed in ascending order of their names.
By separating program blocks for individual functions and processing, the order of programs can be changed easily and
programs can be exchanged easily.
The program of a program block is stored by each registration destination program in a program file.
Creating a main routine program, subroutine program, and interrupt program separately in individual program blocks enables
creation of easy-to-understand programs. *1
*1 Subroutine programs and interrupt programs cannot be created in safety programs. Subroutine programs cannot be executed from
safety programs.
For details on the main routine program, subroutine program, and interrupt program, refer to the following.
MELSEC iQ-R CPU Module User's Manual (Application)
• Create a subroutine program and interrupt program after the FEND instruction of the main routine program. Any program
after the FEND instruction is not executed as a main routine program. For example, when the FEND instruction is used at
the end of the second program block, the third program block or later runs as a subroutine program or interrupt program.
• To create an easy-to-understand program, use a pair of instructions, such as the FOR and NEXT instructions or the MC
and MCR instructions, within a single program block.
• A simple program can be executed in the CPU module simply by writing the main routine in one program block.
Program type Description
Main routine program A program beginning with step 0 and ending with the FEND instruction
Subroutine program A program beginning with a pointer (P) and ending with the RET instruction.
This program is executed only when it is called by a subroutine call instruction (such as the CALL and ECALL
instructions).
Interrupt program A program beginning with an interrupt pointer (I) and ending with the IRET instruction.
When an interrupt factor occurs, the interrupt program corresponding to the interrupt pointer number is executed.
Program file
Program block 1
Program block 2

3 PROGRAM ORGANIZATION UNITS
3.2 Functions (FUN) 15
3
3.2 Functions (FUN)
A function is a POU called and executed by program blocks, function blocks, and other functions.
After the processing completes, a function passes a value to the calling source. This value is called a return value.
A function always outputs the same return value, as the processing result, for the same input.
By defining simple, independent algorithms that are frequently used, functions can be reused efficiently.
Input variables and output variables
Input and output variables can be defined in functions. Output data which is different from the return value can be assigned to
the output variable.
For the classes in which input and output variables can be set, refer to the following.
Page 39 Classes
Variables defined in the function are overwritten every time the function is called.
To hold the data in the variables, create a program by using function blocks or so that the data in the output
variable is saved in another variable.
Ladder program FBD/LD program
The return value of the function is not displayed.
(1) Function name
(2) Input variable
(3) Output variable
FUN
FB or FUNFUN
Program
blockFunction
Function block
or
function
Program
block
(1)
(2)
(3)
(1)
(2)
(3)

16 3 PROGRAM ORGANIZATION UNITS
3.2 Functions (FUN)
EN and ENO
EN (enable input) and ENO (enable output) can be appended to a function to control execution processing.
• Set a boolean variable used as an execution condition of a function to EN.
• A function with EN is executed only when the execution condition of EN is TRUE.
• Set a boolean variable used to output a function execution result to ENO.
For the boolean type, refer to the following.
Page 40 Data Types
The following table lists the ENO states and operation results according to the EN states.
• Setting an output label to ENO is not always required for the program written in ladder or FBD/LD.
• When EN/ENO is used in a standard function, the function with EN is represented by "function-name_E".
Creating programs
The program of a function can be created by using the engineering tool.
[Navigation window] [FB/FUN] Right-click [Add New Data]
The created program is stored in the FB/FUN file.
[CPU Parameter] [Program Setting] [FB/FUN File Setting]
Up to 64 programs can be stored in one FB/FUN file.
For details on program creation, refer to the following.
■Applicable devices and labels
The following table lists the devices and labels that can be used in function programs.
: Applicable, : Applicable only in instructions (Cannot be used to indicate the program step.), : Not applicable
*1 The following data types cannot be used.
Timer, retentive timer, counter, long timer, long retentive timer, and long counter
Program a function name as a label in a function to set a return value of the function. Setting function names
as labels is not necessary. The data type set in "Result Type" in the properties of the function can be used.
EN ENO Operation result
TRUE (executed) TRUE Operation result output value
FALSE (not executed) FALSE Undefined value
Item Reference
How to create function programs GX Works3 Operating Manual
Number of FB/FUN files that can be written to a CPU module MELSEC iQ-R CPU Module User's Manual (Startup)
Type of device/label Availability
Label (other than the pointer type) Global label 
Local label *1
Label (pointer type) Pointer type global label 
Pointer type local label 
Device Global device 
Local device 
Pointer Global pointer 
Local pointer 

3 PROGRAM ORGANIZATION UNITS
3.2 Functions (FUN) 17
3
Operation overview
The program of a function is stored in the FB/FUN file and called by the calling source program when executed.
Up to 32 subroutine type function blocks, macro type function blocks, and functions in total can be nested.
Labels defined by a function
The labels defined by a function are assigned in the temporary areas of the storage-target memory during execution of the
function, and the areas are freed after the processing completes.
The following figure shows the label assignments while the above functions are being executed.
For the types of labels can be defined by a function, refer to the following.
Page 39 Classes
The label to be defined by a function must be initialized by a program before the first access because the label
value will be undefined.
ÒÓÔ
ÕÖ
×
Ø
FUN1
FUN2
FUN3
(Program file)
Main program
(FB file)
FUN1 program
(FB file)
FUN2 program
(FB file)
FUN3 program
Execution
flow
ÒÓÔÕ
Ö×Ø
Label area of FUN3
Main program being
executed
FUN1 being executed
(before FUN3 is called)
FUN3 being executed
Label area of FUN1 Label area of FUN1 Label area of FUN1
FUN1 being executed
(after FUN3 is executed)
Main program being
executed
FUN2 being executed
Label area of FUN2
Main program being
executed

18 3 PROGRAM ORGANIZATION UNITS
3.2 Functions (FUN)
Number of steps
To call a function, the number of steps is required not only for the program itself but also for the processing that passes the
argument and return value and the processing that calls the program.
■Program
The number of steps required for a function program is the total number of instruction steps plus 22 steps. For the number of
steps required for each instruction, refer to the following.
MELSEC iQ-R Programming Manual (Instructions, Standard Functions/Function Blocks)
■Calling source
When calling a function, the calling source generates the processing that passes the argument and return value before and
after the call processing.
• Passing the argument
The instruction used to pass the argument differs depending on the class and data type of the argument. The following table
summarizes the instructions that can be used to pass the argument.
• Calling the program
A total of 26 steps are required to call the program of a function.
(1) Passing the argument
(2) Calling the FUN1 program
(3) Passing the return value
Argument
class
Data type Instruction used Number of steps
VAR_INPUT Bit LD+OUT
LD+MOVB
(Either of the instruction sets is used
depending on the combination of
programming language, function, and input
argument used.)
For the number of steps required for
each instruction, refer to the following.
MELSEC iQ-R Programming
Manual (Instructions, Standard
Functions/Function Blocks)
Word [unsigned]/bit string [16 bits]
Double word [unsigned]/bit string [32 bits]
Word [signed]
Double word [signed]
LD+MOV
LD+DMOV
Single-precision real number LD+EMOV
Double-precision real number LD+EDMOV
Time LD+DMOV
String LD+$MOV
String [Unicode] LD+$MOV_WS
Array, Structure LD+BMOV
(1)
(2)
(3)
FUN1
FUNCall FUN1
FUN2
MOV D0 XX
D0
M0
D10
M10 Y40
Y20
M0
Y20
·
Program file
FUN1 program
FB file
The call-target program is
replaced with the call
instruction.
Program block 1
(displayed)
Calling the function