Mitsubishi Electric MELSEC iQ-F FX5 Owner's manual

MELSEC iQ-F
FX5 Programming Manual (Program Design)

1
SAFETY PRECAUTIONS
(Read these precautions before using this product.)
Before using the FX5 PLCs, please read the manual supplied with each product and the relevant manuals introduced in that
manual carefully and pay full attention to safety to handle the product correctly.
Store this manual in a safe place so that it can be taken out and read whenever necessary. Always forward it to the end user.
INTRODUCTION
This manual describes the instructions and functions required for programming of the FX5. Please read this manual and the
relevant manuals and understood the functions and performance of the FX5 PLCs before attempting to use the unit.
It should be read and understood before attempting to install or use the unit. Store this manual in a safe place so that you can
take it out and read it whenever necessary. Always forward it to the end user.
When utilizing the program examples introduced in this manual to the actual system, always confirm that it poses no problem
for control of the target system.
Regarding use of this product
• This product has been manufactured as a general-purpose part for general industries, and has not been designed or
manufactured to be incorporated in a device or system used in purposes related to human life.
• Before using the product for special purposes such as nuclear power, electric power, aerospace, medicine or passenger
movement vehicles, consult with Mitsubishi Electric.
• This product has been manufactured under strict quality control. However when installing the product where major
accidents or losses could occur if the product fails, install appropriate backup or failsafe functions in the system.
Note
• If in doubt at any stage during the installation of the product, always consult a professional electrical engineer who is
qualified and trained to the local and national standards. If in doubt about the operation or use, please consult the nearest
Mitsubishi Electric representative.
• Since the examples indicated by this manual, technical bulletin, catalog, etc. are used as a reference, please use it after
confirming the function and safety of the equipment and system. Mitsubishi Electric will accept no responsibility for actual
use of the product based on these illustrative examples.
• This manual content, specification etc. may be changed without a notice for improvement.
• The information in this manual has been carefully checked and is believed to be accurate; however, if you have noticed a
doubtful point, a doubtful error, etc., please contact the nearest Mitsubishi Electric representative. When doing so, please
provide the manual number given at the end of this manual.

2
CONTENTS
SAFETY PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
RELEVANT MANUALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
TERMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
CHAPTER 1 OUTLINE 7
CHAPTER 2 PROGRAM CONFIGURATION 9
2.1 Program Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
CHAPTER 3 PROGRAM ORGANIZATION UNIT (POU) 11
3.1 Function (FUN). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.2 Function Block (FB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
CHAPTER 4 LABELS 22
4.1 Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.2 Class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.3 Data Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.4 Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.5 Structures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
4.6 Constant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.7 Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
CHAPTER 5 LADDER DIAGRAM 33
5.1 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Ladder symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Program execution order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5.2 Inline ST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
5.3 Statements and Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
CHAPTER 6 ST LANGUAGE 37
6.1 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Delimiter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Constant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Label and device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Comment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
CHAPTER 7 FBD/LD language 49
7.1 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Program unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Worksheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Constant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Labels and devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
7.2 Program execution order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
The order of executions of program units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

3
CONTENTS
INDEX 56
REVISIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58
WARRANTY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59
TRADEMARKS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60

4
RELEVANT MANUALS
User's manuals for the applicable modules
Manual name <manual number> Description
MELSEC iQ-F FX5 User's Manual (Startup)
<JY997D58201>
Performance specifications, procedures before operation, and troubleshooting of the
CPU module.
MELSEC iQ-F FX5U User's Manual (Hardware)
<JY997D55301>
Describes the details of hardware of the FX5U CPU module, including input/output
specifications, wiring, installation, and maintenance.
MELSEC iQ-F FX5UC User's Manual (Hardware)
<JY997D61401>
Describes the details of hardware of the FX5UC CPU module, including input/output
specifications, wiring, installation, and maintenance.
MELSEC iQ-F FX5 User's Manual (Application)
<JY997D55401>
Describes basic knowledge required for program design, functions of the CPU
module, devices/labels, and parameters.
MELSEC iQ-F FX5 Programming Manual (Program Design)
<JY997D55701> (This manual)
Describes specifications of ladders, ST, FBD/LD, and other programs and labels.
MELSEC iQ-F FX5 Programming Manual (Instructions, Standard
Functions/Function Blocks)
<JY997D55801>
Describes specifications of instructions and functions that can be used in programs.
MELSEC iQ-F FX5 User's Manual (Serial Communication)
<JY997D55901>
Describes N:N network, MELSEC Communication protocol, inverter communication,
non-protocol communication, and predefined protocol support.
MELSEC iQ-F FX5 User's Manual (MODBUS Communication)
<JY997D56101>
Describes MODBUS serial communication.
MELSEC iQ-F FX5 User's Manual (Ethernet Communication)
<JY997D56201>
Describes the functions of the built-in Ethernet port communication function.
MELSEC iQ-F FX5 User's Manual (SLMP)
<JY997D56001>
Explains methods for the device that is communicating with the CPU module by
SLMP to read and write the data of the CPU module.
MELSEC iQ-F FX5 User's Manual (Positioning Control)
<JY997D56301>
Describes the built-in positioning function.
MELSEC iQ-F FX5 User's Manual (Analog Control)
<JY997D60501>
Describes the analog function.
GX Works3 Operating Manual
<SH-081215ENG>
System configuration, parameter settings, and online operations of GX Works3.

5
TERMS
Unless otherwise specified, this manual uses the following terms.
• indicates a variable part to collectively call multiple models or versions.
(Example) FX5U-32MR/ES, FX5U-32MT/ES FX5U-32M/ES
• For details on the FX3 devices that can be connected with the FX5, refer to FX5 User’s Manual (Hardware).
Terms Description
■Devices
FX5 Abbreviation of FX5 PLCs
FX3 Generic term for FX3S, FX3G, FX3GC, FX3U, and FX3UC PLCs
FX5 CPU module Generic term for FX5U CPU module and FX5UC CPU module
FX5U CPU module Generic term for FX5U-32MR/ES, FX5U-32MT/ES, FX5U-32MT/ESS, FX5U-64MR/ES, FX5U-64MT/ES,
FX5U-64MT/ESS, FX5U-80MR/ES, FX5U-80MT/ES, and FX5U-80MT/ESS
FX5UC CPU module Generic term for FX5UC-32MT/D and FX5UC-32MT/DSS
Extension module Generic term for FX5 extension modules and FX3 function modules
• FX5 extension module Generic term for I/O modules, FX5 extension power supply module, and FX5 intelligent function module
• FX3 extension module Generic term for FX3 extension power supply module and FX3 special function blocks
Extension module (extension cable type) Input modules (extension cable type), Output modules (extension cable type), Bus conversion module
(extension cable type), and Intelligent function modules
Extension module (extension connector type) Input modules (extension connector type), Output modules (extension connector type), Input/output
modules, Bus conversion module (extension connector type), and Connector conversion module (extension
connector type)
I/O module Generic term for input modules, output modules, Input/output modules, and powered input/output modules
Input module Generic term for Input modules (extension cable type) and Input modules (extension connector type)
• Input module (extension cable type) Generic term for FX5-8EX/ES and FX5-16EX/ES
• Input module (extension connector type) Generic term for FX5-C32EX/D and FX5-C32EX/DS
Output module Generic term for output modules (extension cable type) and output modules (extension connector type)
• Output module (extension cable type) Generic term for FX5-8EYR/ES, FX5-8EYT/ES, FX5-8EYT/ESS, FX5-16EYR/ES, FX5-16EYT/ES, and
FX5-16EYT/ESS
• Output module (extension connector type) Generic term for FX5-C32EYT/D and FX5-C32EYT/DSS
Input/output modules Generic term for FX5-C32ET/D and FX5-C32ET/DSS
Powered input/output module Generic term for FX5-32ER/ES, FX5-32ET/ES, and FX5-32ET/ESS
Extension power supply module Generic term for FX5 extension power supply module and FX3 extension power supply module
• FX5 extension power supply module Different name for FX5-1PSU-5V
• FX3 extension power supply module Different name for FX3U-1PSU-5V
Intelligent module The abbreviation for intelligent function modules
Intelligent function module Generic term for FX5 intelligent function modules and FX3 intelligent function modules
• FX5 intelligent function module Generic term for FX5 intelligent function modules
• FX3 intelligent function module Generic term for FX3 special function blocks
Simple motion module Different name for FX5-40SSC-S
Expansion board Generic term for board for FX5U CPU module
• Communication board Generic term for FX5-232-BD, FX5-485-BD, and FX5-422-BD-GOT
Expansion adapter Generic term for adapter for FX5 CPU module
• Communication adapter Generic term for FX5-232ADP and FX5-485ADP
• Analog adapter Generic term for FX5-4AD-ADP and FX5-4DA-ADP
Bus conversion module Generic term for Bus conversion module (extension cable type) and Bus conversion module (extension
connector type)
• Bus conversion module (extension cable
type)
Different name for FX5-CNV-BUS
• Bus conversion module (extension connector
type)
Different name for FX5-CNV-BUSC
Battery Different name for FX3U-32BL
Peripheral device Generic term for engineering tools and GOTs
GOT Generic term for Mitsubishi Graphic Operation Terminal GOT1000 and GOT2000 series

6
■Software packages
Engineering tool The product name of the software package for the MELSEC programmable controllers
GX Works3 The product name of the software package, SWnDND-GXW3, for the MELSEC programmable controllers
(The 'n' represents a version.)
■Manuals
User's manual Generic term for separate manuals
• User's manual (Startup) Abbreviation of MELSEC iQ-F FX5 User's Manual (Startup)
• FX5 User's manual (Hardware) Generic term for MELSEC iQ-F FX5U User's Manual (Hardware) and MELSEC iQ-F FX5UC User's Manual
(Hardware)
• FX5U User's manual (Hardware) Abbreviation of MELSEC iQ-F FX5U User's Manual (Hardware)
• FX5UC User's manual (Hardware) Abbreviation of MELSEC iQ-F FX5UC User's Manual (Hardware)
• User's manual (Application) Abbreviation of MELSEC iQ-F FX5 User's Manual (Application)
Programming manual (Program Design) Abbreviation of MELSEC iQ-F FX5 Programming Manual (Program Design)
Programming manual (Instructions, Standard
Functions/Function Blocks)
Abbreviation of MELSEC iQ-F FX5 Programming Manual (Instructions, Standard Functions/Function Blocks)
Communication manual Generic term for MELSEC iQ-F FX5 User's Manual (Serial Communication), MELSEC iQ-F FX5 User's
Manual (MODBUS Communication), MELSEC iQ-F FX5 User's Manual (Ethernet Communication), and
MELSEC iQ-F FX5 User's Manual (SLMP)
• Serial communication manual Abbreviation of MELSEC iQ-F FX5 User's Manual (Serial Communication)
• MODBUS communication manual Abbreviation of MELSEC iQ-F FX5 User's Manual (MODBUS Communication)
• Ethernet communication manual Abbreviation of MELSEC iQ-F FX5 User's Manual (Ethernet Communication)
• SLMP manual Abbreviation of MELSEC iQ-F FX5 User's Manual (SLMP)
Positioning manual Abbreviation of MELSEC iQ-F FX5 User's Manual (Positioning Control)
Analog manual Abbreviation of MELSEC iQ-F FX5 User's Manual (Analog Control)
■Program
Operand A generic term for items, such as source data (s), destination data (d), number of devices (n), and others,
used to configure instructions and functions
Device A device (X, Y, M, D, or others) in a CPU module
Buffer memory A memory in an intelligent function module, where data (such as setting values and monitoring values) are
stored.
POU Defined unit of a program. Use of POUs enables a program to be divided into units according to process or
function, and each unit to be programmed individually.
Terms Description

1 OUTLINE
7
1
1OUTLINE
This manual describes program configurations, content, and method for creating programs.
For how to create, edit, or monitor programs using the engineering tool, refer to the following.
GX Works3 Operating Manual
Type of programming languages
With the FX5 series, the optimal programming language can be selected according to the application.
■Ladder diagram
When using ladder diagram, refer to the following.
Page 33 LADDER DIAGRAM
■ST language
When using ST language, refer to the following.
Page 37 ST LANGUAGE
■FBD/LD language
When using FBD/LD language, refer to the following.
Page 49 FBD/LD language
Programming language Description
Ladder diagram Ladder diagram is a graphic language that indicates circuits using contacts, coils, and others.
The ladder diagram describes logic circuits with symbolized contacts and coils for easy-to-understand
sequence control.
Structured text language (ST language) ST language is a text language that describes programs with IF statements, operators, and others.
Because operation processing that is difficult to describe in ladder diagram can be easily and briefly
described with ST language, ST language is suitable for applications requiring complicated arithmetic
operation or comparative operation. With ST language, programs can be easily described with syntax
using selective branches with conditional statements and repetition by repetitive statements in the
same way as C language.
Function block diagram/ladder diagram
(FBD/LD language)
This is a graphic language that describes a program by wiring blocks for specific processing (function
elements, FB elements), variable elements, and constant elements along with the flows of data and
signals.
You can easily create a program that may be complicated to create by using a ladder program. So you
can enhance the productivity of programs.

81 OUTLINE
• Ladder diagram and FBD/LD language are for customers who have knowledge or experience of sequence
control and logic circuits.
• ST language is for customers who have knowledge or experience of the C language programming.
• By using labels in a program, the readability of the program is improved, and activating a program for the
system with a different module configuration is easy.

2 PROGRAM CONFIGURATION
9
2
2PROGRAM CONFIGURATION
Using the engineering tool, multiple programs and POUs (Program Organization Units) can be created.
Thus, programs and POUs can be sorted by processing.
This chapter describes the program configuration.
For the POU, refer to the following.
Page 11 PROGRAM ORGANIZATION UNIT (POU)
Project
A project is a collection of data (including programs and parameters) to be executed by the CPU module.
Only one project can be written to one CPU module.
For one project, one or more program files need to be created.
Program file
A program file is a collection of programs and POUs.
One program file consists of one or more program blocks.
The operation on the program file level can be changed, such as, the execution type of a program can be switched from scan
execution type to standby type, or whether to write data to the CPU module.
Project
Program file 1
Program block Program block
Function block
Function block
Function
Function
Function
Program block
Program file 2 POUs

10 2 PROGRAM CONFIGURATION
2.1 Program Block
2.1 Program Block
A program block is a unit of a program.
Multiple program blocks can be created in one program file, and are executed in the registered order.
By dividing program blocks by functions or processing, changing the program order or replacing the program becomes easy.
Program blocks are stored in program files of each program in the registration destination.
Creating main routine programs, subroutine programs, and interrupt programs for each program block makes the program
easy to read.
For details on the main routine program, subroutine program, and interrupt program, refer to the following.
User's manual (Application)
• Create subroutine programs and interrupt programs after the FEND instruction. The program area after the FEND
instruction is not executed as the main routine program. For example, when the FEND instruction is used at the end of the
second program block, the third program block and later are handled as subroutine programs or interrupt programs.
• To make the program easy to read, use twin instructions, such as FOR and NEXT instructions and MC and MCR
instructions, in the same program block.
• A simple program can be executed by the CPU module with just a main routine program in one program block.
Type Description
Main routine program Program segment from the step 0 to the FEND instruction
Subroutine program Program segment from a pointer (P) to the RET instruction
Executed only when a subroutine call instruction (CALL instruction etc.) is executed.
Interrupt program Program segment from an interrupt pointer (I) to the IRET instruction
When an interrupt is triggered, the interrupt program corresponding to the interrupt pointer number is executed.
Program file
Program block 1
Program block 2

3 PROGRAM ORGANIZATION UNIT (POU)
11
3
3PROGRAM ORGANIZATION UNIT (POU)
The POU includes the following types.
• Function
• Function block
The processing of each POU can be described in a programming language according to the control. POUs are called from a
program block, and then executed.
A structured program is a program created by components. Processes in lower levels of hierarchical program
are divided to several components according to their processing information and functions.
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 program
• A process that can be divided into functions
This chapter describes two types of POUs using labels.
Devices can also be used in the program of a function or function block. For details on devices, refer to the following.
User's manual (Application)
Project
Program file
POU folder
POU
Program block
POU
Function block
POU
Function
Use

12 3 PROGRAM ORGANIZATION UNIT (POU)
3.1 Function (FUN)
3.1 Function (FUN)
Functions are a type of POU used by program blocks, function blocks, or other functions.
The function sends back a value to the call source after execution. The value is called return values.
The function always outputs the same return value as the processing result in response to the same input.
The function can be re-used effectively by defining a simple, independent, and frequently used algorithm.
Input variable and output variable
For a function, input variables and output variables can be defined. Output variable can be created to output data separate
from the return value.
For classes for which input variables or output variables can be set, refer to the following.
Page 23 Class
Variables defined in a function are overwritten every time the function is called.
To retain the variable values at each call, use a function block or design a program so that an output variable
is saved in a different variable.
Case of ladder diagram Case of FBD/LD language
(1) Function name
(2) Input variables
(3) Output variables
FUN
FB or FUNFUN
Function
Function block
or function
Program block
Program block
(1)
(2)
(3)
(1)
(2)
(3)

3 PROGRAM ORGANIZATION UNIT (POU)
3.1 Function (FUN) 13
3
EN/ENO
An EN (enable input) and ENO (enable output) can be appended to a function to control its execution.
• A Boolean variable used as an executing condition of a function is set to an EN.
• A function with an EN is executed only when the executing condition of the EN is TRUE.
• A Boolean variable used as an output of function execution result is set to an ENO.
For the Boolean variable, refer to the following.
Page 23 Data Type
The table below shows the "ENO" status corresponding to the "EN" status and the operation result.
• Setting an output label to an ENO is not required.
• When an EN or ENO is used for standard functions, functions with an EN are shown as "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 by instructions (Not applicable as a label indicating a program step), : Not applicable
*1 The timer, retentive timer, counter and long counter types cannot be used.
EN ENO Operation result
TRUE (Executes operation) TRUE Operation output value
FALSE (Stops operation) FALSE Indefinite 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 User's manual (Startup)
Type of device/label Availability
Label (other than pointer type) Global label 
Local label *1
Label (pointer type) Pointer type global label 
Pointer type local label 
Device Global device 
Pointer Global pointer 

14 3 PROGRAM ORGANIZATION UNIT (POU)
3.1 Function (FUN)
Operation overview
The program of a function is stored in the FB/FUN file and called by the calling source program when executed
You can nest all function blocks and functions up to 32 times.
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 that can be defined by a function, refer to the following.
Page 23 Class
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.
Number of steps
To call a function, the number of steps required is not only for the program itself but also for the processing that passes the
argument and return value, the processing that calls the program, and additional steps used by the system.
■Program
The number of steps required for a function program is the total number of instruction steps plus at least additional 13 steps
used by the system. For the number of steps required for each instruction, refer to the following.
Programming manual (Instructions, Standard Functions/Function Blocks)
FUN1
(Program file)
Main program (FB file)
FUN1 program (FB file)
FUN3 program
(FB file)
FUN2 program
FUN3
FUN2
Execution flow
123
4
5
7
6
Main program being
executed
Main program being
executed
Main program being
executed
FUN1 being executed
(before FUN3 is called)
FUN1 being executed
(after FUN3 is executed)
FUN3 being executed
FUN2 being executed
Label area of FUN1
Label area of FUN2
Label area of FUN1 Label area of FUN1
Label area of FUN3
1 2 3 4
5 6 7

3 PROGRAM ORGANIZATION UNIT (POU)
3.1 Function (FUN) 15
3
■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
At least 16 steps are required to call the program of a function.
Passing the return value
The instruction and the number of steps used for passing the return value are identical to those for passing the argument.
EN/ENO
The following table lists the number of steps required for EN/ENO.
Precautions
■Global pointer/local pointer/pointer type global labels
Global pointer, local pointer, and pointer type global labels cannot be used as labels indicating program steps in the function
program.
(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
(Which of the above instructions is used is
determined by the combination of the
programming language, type of function, and
type of input argument.)
For the number of steps required for
each instruction, refer to the
following.
Programming manual
(Instructions, Standard Functions/
Function Blocks)
Word [Unsigned]/Bit String [16-bit]
Double Word [Unsigned]/Bit String [32-bit]
Word [Signed]
Double Word [Signed]
LD+MOV
LD+DMOV
FLOAT [Single Precision] LD+EMOV
Time LD+DMOV
String(32) LD+$MOV
Array, Structure LD+BMOV
Argument class Data type Instruction used Number of steps
VAR_OUTPUT Same as for passing the argument Same as for passing the argument Same as for passing the argument
Item Number of steps
EN 6
ENO 4
FUN1
M0
M0
MOV D0 XX
(1)
(2)
(3)
Calling the function
FUNCall FUN1
Y20
…
Y20
D0
FUN2
M10 Y40
D10
Program block 1
(displayed) Program file
FB file
FUN1 program
The call-target program
is replaced with the call
instruction.

16 3 PROGRAM ORGANIZATION UNIT (POU)
3.2 Function Block (FB)
3.2 Function Block (FB)
Function blocks are a type of POU used by program blocks or other function blocks.
Unlike the function, the function block does not output return values.
The function block can save a value in a variable, and thus the input status and processing result are retained.
Because the retained value is used for the next processing, the same result is not always output even with the same input
value.
To use the function block in a program, instances must be defined.
Page 17 Instances
Input variable, output variable, and input/output variable
Input variables, output variables, and input/output variables must be defined for function blocks.
The function block can output multiple operation results and can also be created without any output.
For classes for which input variables, output variables, or input/output variables can be set, refer to the following.
Page 23 Class
Case of ladder diagram Case of FBD/LD language
(1) Instance name
(2) Function block name
(3) Output variables
(4) Input variables
(1) Multiple outputs are returned.
(2) No outputs are returned.
FB
FBFB
Function blockFunction block
Function block Function block
(2)
(1)
(4)
(3)
(2)
(1)
(4)
(3)
_S1 Q1
RESET
IN_Bool
iTim
lCnt
CD Q
CVLOAD
PV
InstanceInstance
Instance
SR SAMPLE_FB1
CTD
(1)
(2)

3 PROGRAM ORGANIZATION UNIT (POU)
3.2 Function Block (FB) 17
3
Internal variable
For the function block, internal variables can be used.
For classes for which internal variables can be set, refer to the following.
Page 23 Class
External variable
For the function block, external variables can be used.
For classes for which external variables can be set, refer to the following.
Page 23 Class
Instances
■Instances
To use the function block, instances must be created.
By creating instances of the function block, the function block can be used by calling from a program or another function
block. Multiple instances can be created from one function block definition.
To create an instance, define it as a global label or local label of the POU that uses the function block. The instance can be
defined as an array.
The same function block can be used in different instances in one POU. For each instance of a function block, labels are
assigned to different areas in memory. Even though the same label names are used, different states are held for each
instance.
Ex.
The above function block starts counting current value when the input variables (Count contact) turn on and turns on the
output variable (Output contact) when the current value held in the internal variable reaches the set value.
Instance A and B are the same function blocks, but instances A and B hold different states because the instance is different.
In the above example, output variable (Output contact) of instance B is already turned ON, but output variable (Output
contact) of instance A is not turned ON. Because the current value of instance A does not reach the set value, output variable
(Output contact) of instance A is not turn ON.
■Structure of instance
An instance consists of the following data areas.
■Capacity of instance
The capacity of each data area of an instance should be calculated as follows.
Local label area
Capacity of local label area of instance = Total capacity of data of non-latched local labels + Capacity of reserved area
Data area Description
Local label area Used to assign local labels of the function block.
Local latch label area Used to assign latched local labels of the function block.
Breakdown Description
Capacity of non-latched local labels Total capacity of the data areas used for local labels.
bLabel3
bLabel1
uLabel2
bLabel6
bLabel4
uLabel5
Instance A
Function block
Count contact
Set value
Output contact
Current value
Count contact
Set value
Output contact
Current value
Instance B
uLabel13 ON
uLabel12 500
uLabel10 ON
uLabel11 500
uLabel12 10
uLabel10 ON
uLabel11 7
uLabel13 OFF

18 3 PROGRAM ORGANIZATION UNIT (POU)
3.2 Function Block (FB)
Local latch label area
Capacity of local latch label area of instance = Total capacity of data of latched local labels + Capacity of reserved area
The local label area capacity is assigned by using the engineering tool. For details, refer to the following.
GX Works3 Operating Manual
EN/ENO
An EN (enable input) and ENO (enable output) can be appended to a function block, in the same way as a function, to control
its execution.
Page 13 EN/ENO
An actual argument must be assigned to EN when the instance of the function block to which an EN/ENO is added is called.
Creating programs
The program of a function block 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.
■Type of programs
There are two types of function blocks and the program of each function block type is stored in different ways.
• Macro type function block
• Subroutine type function block
For details, refer to the following.
Page 19 Operation overview
The above cannot be selected for module function blocks, standard functions, and standard function blocks.
■Applicable devices and labels
The following table lists the devices and labels that can be used by function block programs.
: Applicable, : Applicable only by instructions (Not applicable as a label indicating a program step)
Capacity of reserved area The capacity of the area reserved to add non-latched local labels and local
instances when executing the online program change function. (fixed at 48
words)
Breakdown Description
Capacity of latched local labels Total capacity of the data areas used for latched local labels.
Capacity of reserved area The capacity of the area reserved to add latched local labels and local
instances when executing the online program change function. (fixed at 16
words)
Item Reference
How to create function programs GX Works3 Operating Manual
Number of FB/FUN files that can be written to a CPU module User's manual (Startup)
Type of device/label Availability
Label (other than pointer type) Global label 
Local label 
Label (pointer type) Pointer-type global label 
Pointer-type local label 
Device Global device 
Pointer Global pointer 
Breakdown Description