Mitsubishi Electric QJ71MT91 User manual

MODBUS/TCP Interface Module User's Manual
-QJ71MT91
-GX Configurator-MB (SW1D5C-QMBU-E)

A-1 A-1
SAFETY PRECAUTIONS 
(Always read these instructions before using this equipment.)
Before using this product, please read this manual and the relevant manuals introduced in this manual
carefully and pay full attention to safety to handle the product correctly.
The instructions given in this manual are concerned with this product. For the safety instructions of the
programmable controller system, please read the user's manual of the CPU module to use.
In this manual, the safety precautions are classified into two levels: " WARNING" and " CAUTION".
Under some circumstances, failure to observe the precautions given under " CAUTION" may lead to
serious consequences.
Observe the precautions of both levels because they are important for personal and system safety.
Make sure that the end users read this manual and then keep the manual in a safe place for future
reference.
[Design Precautions]
WARNING
When connecting a peripheral with the CPU module or connecting a personal computer with an
intelligent function module to modify data of a running programmable controller, configure an
interlock circuit in the sequence program to ensure that the entire system will always operate
safely. For other forms of control (such as program modification, parameter change, forced
output, or operating status change) of a running programmable controller, read the relevant
manuals carefully and ensure that the operation is safe before proceeding.
Especially in the above mentioned control operations that are performed from an external
device to a remote programmable controller, any problems on the programmable controller side
may not be dealt with promptly due to a data communication error. To prevent this, configure an
interlock circuit in the sequence program, and determine corrective actions to be taken between
the external device and programmable controller in case of a communication failure.
Do not write any data in the "system area (Use prohibited)" of the buffer memory of the
intelligent function module. Also, do not output (turn on) the "use prohibited" signal, which is one
of the output signals from the programmable controller CPU to the intelligent function module. If
data is written to the "system area (Use prohibited)" or the "use prohibited" signal is output, there
is a risk that the programmable controller system may malfunction.

A-2 A-2
CAUTION
Do not bundle the control wires and the communication cables with the main circuit and the
power wires, and do not install them close to each other. They should be installed at least 100
mm (3.94 in.) away from each other. Failure to do so may generate noise that may cause
malfunctions.
[Installation Precautions]
CAUTION
Be sure to shut off all phases of the external power supply used by the system before mounting
or removing the module.
Failure to do so may damage the module.
Use the programmable controller in the operating environment that meets the general
specifications described in the user's manual of the CPU Module to use. Using the
programmable controller in any other operating environments may cause electric shocks, fires
or malfunctions, or may damage or degrade the module.
To mount the module, while pressing the module mounting lever located in the lower part of the
module, fully insert the module fixing projection(s) into the hole(s) in the base unit and press the
module until it snaps into place.
Incorrect module mounting may cause a malfunction, failure, or drop of the module.
In an environment of frequent vibrations, secure the module with the screw.
Be sure to tighten the screws using the specified torque. If the screws are loose, it may cause
the module to short-circuit, malfunction or fall off. If the screws are tightened excessively, it may
damage the screws and cause the module to short-circuit, malfunction or fall off.
Do not directly touch any conductive part or electronic component of the module.
Doing so may cause a malfunction or failure of the module.
[Wiring Precautions]
WARNING
Shut off the external power supply (all phases) used in the system before wiring.
Failure to do so may result in electric shock or damage to the product.

A-3 A-3
CAUTION
Connectors for external connection must be crimped or pressed with the tool specified by the
manufacturer, or must be correctly soldered.
Incomplete connections could result in short circuit, fire, or malfunction.
Securely connect the connector to the module. Failure to do so may cause malfunction.
Place the cables in a duct or clamp them. If not, dangling cable may swing or inadvertently be
pulled, resulting in damage to the module or cables or malfunction due to poor contact.
In addition, the weight of the cables may put stress on modules in an environment of strong
vibrations and shocks.
Before connecting the cables, check the type of interface to be connected.
Connecting or erroneous wiring to the wrong interface may cause failure to the module and
external devices.
When disconnecting the cable from the module, do not pull the cable by the cable part.
For the cable with connector, hold the connector part of the cable.
Pulling the cable connected to the module may result in malfunction or damage to the module or
cable.
Be careful not to let any foreign matter such as wire chips get inside the module.
They may cause fire, as well as breakdowns and malfunctions of the module.
A protective film is attached to the top of the module to prevent foreign matter, such as wire
chips, from entering the module during wiring.
Do not remove this protective sheet during wiring work. However, be sure to remove the
protective sheet before operating the module to allow heat radiation during operation.
[Setup and Maintenance Precautions]
WARNING
Do not touch the terminals while the power is on. Doing so will cause electric shock or
malfunction.
Before cleaning the module or retightening the module mounting screws, make sure to shut off
all phases of the external power supply used by the system. Failure to do so may cause the
module to electric shocks, breakdown or malfunction.

A-4 A-4
CAUTION
Before performing online operations (especially, program modification, forced output or
operating status change) by connecting a peripheral device to a running CPU, read the manual
carefully and ensure the safety. Incorrect operation will cause mechanical damage or accidents.
Never disassemble or modify the module. This may cause breakdowns, malfunctions, injuries or
fire.
When using a wireless communication device such as a cellular phone, keep a distance of 25cm
(9.85 inch) or more from the programmable controller in all directions. Failure to do so can
cause a malfunction.
Before mounting/dismounting the module, be sure to shut off all phases of the external power
supply used by the system. Failure to do so may cause module failure or malfunctions.
After the first use of the product, do not mount/remove the module to/from the base unit more
than 50 times ((IEC 61131-2/JIS B 3502 compliant).
Failure to do so may cause malfunction.
Before handling the module, touch a conducting object such as a grounded metal to discharge
the static electricity from the human body.
Failure to do so may cause a failure or malfunctions of the module.
[Operating Precautions]
CAUTION
When changing data and operating status, and modifying program of the running programmable
controller from an external device such as a personal computer connected to an intelligent
function module, read relevant user's manuals carefully and ensure the safety before operation.
Incorrect modifications of data, programs and operating status may cause system malfunctions,
damages to the machines, or accidents.
[Disposal Precautions]
CAUTION
Dispose of this product as an industrial waste.

A-5 A-5
CONDITIONS OF USE FOR THE PRODUCT 

A-6 A-6
REVISIONS
The manual number is given on the bottom left of the back cover.
Print Date Manual Number Revision
Jan., 2004 SH (NA) -080446ENG-A First Edition
Mar., 2004 SH (NA) -080446ENG-B Modifications
Section 7.2.2, 8.3.2, 8.4, 8.6, 8.7, 9.2.2, 11.1, 11.4, 11.5
Nov., 2005 SH (NA) -080446ENG-C Modifications
Section 4.3.10, 5.2.1, 6.1, 6.2, 6.6, 7.1, 7.3.1, 7.4.1 to 7.4.5, 8.2.2,
8.3.1, 8.3.3, 8.7.2, 9.1, 10.2, 10.3, 11.1, 11.2, 11.3.2, 11.3.3, 11.4
Feb., 2006 SH (NA) -080446ENG-D Modifications
Section 2.1, 2.4, 10.1
Jan., 2008 SH (NA) -080446ENG-E Modifications
SAFETY PRECAUTIONS, Conformation to the EMC Directive and
Low Voltage Instruction, About the Generic Terms and
Abbreviations, Section 2.1, 2.5, 3.1, 3.2.1, 5.1, 5.2.1, 5.5, 6.1, 6.4,
6.6, 7.2.2, 7.4.1, 7.4.2, 7.4.4, Chapter 8, Section 9.1.3, 9.3.1, 9.3.2,
9.3.3, 10.2, 10.3, 11.1, 11.2, 11.3.1, 11.3.3, 11.4.1, 11.4.2, 11.5.1
Addition
Section 2.4
May, 2008 SH (NA) -080446ENG-F Change of a term
"PLC" was changed to "programmable controller".
Modifications
SAFETY PRECAUTIONS, Compliance with the EMC and Low
Voltage Directives, About the Generic Terms and Abbreviations,
Section 2.1, 3.1, 6.1, 6.6, 7.4.2, 8.2.1, 8.3.1, 8.3.3, 8.6, 10.2, 10.3,
11.2, 11.3.3, Appendix 3
Nov., 2010 SH (NA)-080446ENG-G Modifications
SAFETY PRECAUTIONS, About the Generic Terms and
Abbreviations, Section 2.1, 2.5, 6.3, 6.6, 8.2.1, 11.2, Appendix,
WARRANTY
Addition
CONDITIONS OF USE FOR THE PRODUCT

A
-7 A-7
The manual number is given on the bottom left of the back cover.
Print Date Manual Number Revision
Oct., 2014 SH (NA)-080446ENG-H Modifications
COMPLIANCE WITH THE EMC AND LOW VOLTAGE
DIRECTIVES, ABOUT THE GENERIC TERMS AND
ABBREVIATIONS, MEANINGS AND DEFINITIONS OF TERMS,
Chapter 1, Section 2.1, 2.2, 2.4, 2.5, 3.1, 3.3.1, 4.3, 4.3.12, 5.1, 6.2,
6.3, 6.5.1, 6.5.2, 6.6, 6.6.1, 7.1, 7.2.2, 7.3.1, 7.4.2, 7.4.4, 8.2.1,
8.2.2, 8.6, 9.1.1, 9.2.2, 9.2.3, 9.3.2, 9.3.3, 10.2, 10.3, 11.1,
11.2,11.3.2, 11.3.3, Appendix 1
Addition
Appendix 2
Change
Appendix 2→Appendix 3, Appendix 3→Appendix 4
Jun., 2019 SH (NA)-080446ENG-I Modifications
SAFETY PRECAUTIONS, Section 2.1, 2.2, 3.1, 4.3.7, 4.3.8, 4.3.10,
4.3.12, 5.2.1, 5.2.2, 5.6, 6.1, 6.4, 7.2.2, 8.3.1, 10.2, 11.1,
WARRANTY
Japanese Manual Version SH(NA)-080445-K
This manual confers no industrial property rights or any rights of any other kind, nor does it confer any patent
licenses. Mitsubishi Electric Corporation cannot be held responsible for any problems involving industrial property
rights which may occur as a result of using the contents noted in this manual.
2004 MITSUBISHI ELECTRIC CORPORATION

A-8 A-8
INTRODUCTION
Thank you for purchasing the Mitsubishi Electric MELSEC-Q series programmable controller.
Before using the equipment, please read this manual carefully to develop full familiarity with the functions
and performance of the Q series programmable controller you have purchased, so as to ensure correct use.
CONTENTS
SAFETY PRECAUTIONS...............................................................................................................................A- 1
CONDITIONS OF USE FOR THE PRODUCT ..............................................................................................A- 5
REVISIONS.....................................................................................................................................................A- 6
INTRODUCTION.............................................................................................................................................A- 8
CONTENTS.....................................................................................................................................................A- 8
COMPLIANCE WITH THE EMC AND LOW VOLTAGE DIRECTIVES.......................................................A-12
THE MANUAL'S USAGE AND STRUCTURE..............................................................................................A-12
ABOUT THE GENERIC TERMS AND ABBREVIATIONS...........................................................................A-14
MEANINGS AND DEFINITIONS OF TERMS...............................................................................................A-15
PRODUCT CONFIGURATION .....................................................................................................................A-15
1 OVERVIEW 1- 1 to 1- 5
1.1 Features .................................................................................................................................................... 1- 1
2 SYSTEM CONFIGURATION 2- 1 to 2-10
2.1 Applicable Systems................................................................................................................................... 2- 1
2.2 Devices Necessary for Network Configuration ........................................................................................ 2- 3
2.3 System Configuration and Access Range ............................................................................................... 2- 5
2.4 Precautions for System Configuration...................................................................................................... 2- 7
2.5 Checking Function Version and Software Version .................................................................................. 2- 8
3 SPECIFICATIONS 3- 1 to 3-10
3.1 Performance Specifications...................................................................................................................... 3- 2
3.2 I/O Signals for Programmable Controller CPU ........................................................................................ 3- 3
3.2.1 I/O signal list ....................................................................................................................................... 3- 3
3.3 Applications and Assignment of Buffer Memory...................................................................................... 3- 5
3.3.1 Buffer memory list .............................................................................................................................. 3- 5
4 MODBUS STANDARD FUNCTIONS 4- 1 to 4-20
4.1 MODBUS Standard Function Support List............................................................................................... 4- 1
4.2 Frame Specifications ................................................................................................................................ 4- 3
4.3 PDU Formats by Functions ...................................................................................................................... 4- 4
4.3.1 Read coils (FC: 01) ............................................................................................................................ 4- 6
4.3.2 Read discrete inputs (FC: 02)............................................................................................................ 4- 7
4.3.3 Read holding registers (FC: 03)......................................................................................................... 4- 8
4.3.4 Read input registers (FC: 04) ............................................................................................................ 4- 9
4.3.5 Write single coil (FC: 05)................................................................................................................... 4-10
4.3.6 Write single register (FC: 06) ............................................................................................................ 4-11
4.3.7 Write multiple coils (FC: 15).............................................................................................................. 4-12

A-9 A-9
4.3.8 Write multiple registers (FC: 16) ....................................................................................................... 4-14
4.3.9 Read file record (FC: 20) (SC: 06).................................................................................................... 4-15
4.3.10 Write file record (FC: 21) (SC: 06) .................................................................................................. 4-17
4.3.11 Mask write register (FC: 22) ........................................................................................................... 4-19
4.3.12 Read/Write multiple registers (FC: 23) ........................................................................................... 4-20
5 FUNCTIONS 5- 1 to 5-15
5.1 Function List .............................................................................................................................................. 5- 1
5.2 Master Function ........................................................................................................................................ 5- 3
5.2.1 Automatic communication function.................................................................................................... 5- 3
5.2.2 Dedicated instructions........................................................................................................................ 5- 9
5.3 Slave Function.......................................................................................................................................... 5-10
5.3.1 Automatic response function ............................................................................................................ 5-10
5.3.2 MODBUS device assignment function ............................................................................................. 5-11
5.4 KeepAlive Function .................................................................................................................................. 5-12
5.5 Router Relay Function ............................................................................................................................. 5-14
5.6 GX Developer Connection Function........................................................................................................ 5-15
6 PRE-OPERATIONAL PROCEDURES AND SETTING 6- 1 to 6-20
6.1 Handling Precautions................................................................................................................................ 6- 1
6.2 Pre-Operational Procedures and Setting ................................................................................................. 6- 2
6.3 Part Names ............................................................................................................................................... 6- 4
6.4 Connection to Ethernet ............................................................................................................................. 6- 6
6.5 Unit Tests .................................................................................................................................................. 6- 8
6.5.1 Hardware test ..................................................................................................................................... 6- 8
6.5.2 Self-loopback test............................................................................................................................... 6- 9
6.6 Intelligent Function Module Switch Setting ............................................................................................. 6-10
6.6.1 Communication starting conditions depending on basic parameter/MODBUS device assignment
parameter starting method setting .................................................................................................... 6-16
7 PARAMETER SETTING 7- 1 to 7-33
7.1 Parameter Settings and Setting Procedure ............................................................................................. 7- 1
7.2 Basic Parameters...................................................................................................................................... 7- 6
7.2.1 Basic parameters details.................................................................................................................... 7- 6
7.2.2 TCP/UDP/IP setting ........................................................................................................................... 7- 8
7.2.3 GX Developer connection information setting.................................................................................. 7-16
7.2.4 MODBUS/TCP setting ...................................................................................................................... 7-17
7.3 Automatic Communication Parameters .................................................................................................. 7-19
7.3.1 Automatic communication parameters details ................................................................................. 7-19
7.4 MODBUS Device Assignment Parameters............................................................................................. 7-23
7.4.1 MODBUS device sizes...................................................................................................................... 7-25
7.4.2 MODBUS device assignment parameters details............................................................................ 7-26
7.4.3 Default assignment parameters........................................................................................................ 7-29
7.4.4 MODBUS extended file register assignment ................................................................................... 7-31
7.4.5 QJ71MT91 buffer memory assignment............................................................................................ 7-32

A-10 A-10
8 UTILITY PACKAGE (GX Configurator-MB) 8- 1 to 8-36
8.1 Functions of the Utility Package ............................................................................................................... 8- 1
8.2 Installing and Uninstalling the Utility Package ......................................................................................... 8- 2
8.2.1 Handling precautions ......................................................................................................................... 8- 2
8.2.2 Operating environment....................................................................................................................... 8- 4
8.3 Utility Package Operation ......................................................................................................................... 8- 6
8.3.1 Common utility package operations .................................................................................................. 8- 6
8.3.2 Operation overview ............................................................................................................................ 8- 9
8.3.3 Starting the Intelligent function module utility................................................................................... 8-11
8.4 Initial Setting ............................................................................................................................................. 8-13
8.5 Auto Refresh Setting................................................................................................................................ 8-15
8.6 Monitor/Test ............................................................................................................................................. 8-17
8.6.1 X/Y Monitor/test................................................................................................................................. 8-21
8.6.2 Basic/MODBUS device assignment parameter status .................................................................... 8-23
8.6.3 Automatic communication status ...................................................................................................... 8-24
8.6.4 Error log ............................................................................................................................................. 8-26
8.6.5 Communication status....................................................................................................................... 8-27
8.6.6 PING test ........................................................................................................................................... 8-29
8.7 Parameter Setting Using GX Configurator-MB ....................................................................................... 8-30
8.7.1 Basic parameters .............................................................................................................................. 8-30
8.7.2 Automatic communication parameters ............................................................................................. 8-33
8.7.3 MODBUS device assignment parameters ....................................................................................... 8-35
9 PROGRAMMING 9- 1 to 9-49
9.1 Parameter Setting ..................................................................................................................................... 9- 1
9.1.1 Basic parameter setting ..................................................................................................................... 9- 1
9.1.2 Automatic communication parameter setting.................................................................................... 9- 4
9.1.3 MODBUS device assignment parameter setting .............................................................................. 9- 7
9.2 Program Example for Normal System Configuration ............................................................................. 9-11
9.2.1 System configuration and program conditions................................................................................. 9-11
9.2.2 Program using utility package........................................................................................................... 9-18
9.2.3 Program without using utility package.............................................................................................. 9-22
9.3 Program Example for Use in MELSECNET/H Remote I/O Network ..................................................... 9-29
9.3.1 System configuration and program conditions................................................................................. 9-29
9.3.2 Program using utility package........................................................................................................... 9-35
9.3.3 Program without using utility package.............................................................................................. 9-39
10 DEDICATED INSTRUCTIONS 10- 1 to 10-18
10.1 Dedicated Instruction List and Available Devices ................................................................................ 10- 1
10.2 Z(P).MBRW ........................................................................................................................................... 10- 2
10.3 Z(P).MBREQ ........................................................................................................................................ 10-11
11 TROUBLESHOOTING 11- 1 to 11-51
11.1 Troubleshooting .................................................................................................................................... 11- 1
11.2 Confirming QJ71MT91 Status .............................................................................................................11-12

A-11 A-11
11.3 Error Codes .......................................................................................................................................... 11-15
11.3.1 Error code storage areas .............................................................................................................. 11-15
11.3.2 Exception code list ........................................................................................................................ 11-21
11.3.3 Error code list ................................................................................................................................ 11-23
11.4 Turning Off the COM.ERR. LED .........................................................................................................11-40
11.4.1 From GX Configurator-MB............................................................................................................ 11-40
11.4.2 Program example for use of sequence program .........................................................................11-43
11.5 Conducting PING Test to Check QJ71MT91 Connection .................................................................. 11-44
11.5.1 From GX Configurator-MB............................................................................................................ 11-45
11.5.2 Program example for use of sequence program .........................................................................11-49
APPENDICES APPX- 1 to APPX- 8
Appendix 1 External Dimensions........................................................................................................... APPX - 1
Appendix 2 Function Upgrade of the QJ71MT91 ................................................................................. APPX - 2
Appendix 3 Processing Time................................................................................................................. APPX - 2
Appendix 4 GX Developer Connection Setup Example ....................................................................... APPX - 6
INDEX IND- 1 to IND- 4

A-12 A-12
COMPLIANCE WITH THE EMC AND LOW VOLTAGE DIRECTIVES
(1) Method of ensuring compliance
To ensure that Mitsubishi programmable controllers maintain EMC and Low
Voltage Directives when incorporated into other machinery or equipment,
certain measures may be necessary. Please refer to one of the following
manuals.
QCPU User's Manual (Hardware Design, Maintenance and Inspection)
Safety Guidelines
(This manual is included with the CPU module or base unit.)
The CE mark on the side of the programmable controller indicates compliance
with EMC and Low Voltage Directives.
(2) Additional measures
To ensure that this product maintains EMC and Low Voltage Directives, please
refer to one of the manuals listed under (1).
THE MANUAL'S USAGE AND STRUCTURE
How to use this manual
This manual describes the pre-operation procedure and functions of the
MODBUS/TCP interface module (QJ71MT91) on a purpose-by-purpose basis.
Refer to the corresponding section when you need to know the following:
(1) Features (Chapter 1)
Chapter 1 describes the features of the QJ71MT91.
(2) System configuration (Chapter 2)
(a) Section 2.1 describes the applicable programmable controller CPUs and
compatible software packages.
(b) Section 2.2 describes the devices necessary to configure a network.
(c) Section 2.3 describes the system configurations that use the QJ71MT91 and
the accessible range.
(3) Performance and specifications (Chapter 3)
(a) Section 3.1 provides the performance specifications of the QJ71MT91.
(b) Section 3.2 and 3.3 give the I/O signal and buffer memory lists of the
QJ71MT91.
(4) MODBUS standard functions supported by the QJ71MT91
(Chapter 4)
(a) Section 4.1 gives a list of MODBUS standard functions supported by the
QJ71MT91.
(b) Section 4.2 and 4.3 provide the frame specifications of the MODBUS
standard functions supported by the QJ71MT91.

A-13 A-13
(5) Usable functions (Chapter 5)
Chapter 5 describes the functions of the QJ71MT91.
(6) Settings and procedures necessary to operate the system (Chapter
6)
Chapter 6 describes the pre-operation settings and procedures.
(7) Parameter setting of the QJ71MT91 (Chapter 7)
Chapter 7 describes the parameter setting procedures and parameter details.
(8) Parameter setting from the utility package (Chapter 8)
Chapter 8 describes the utility package operation method.
(9) Parameter setting from sequence programs (Chapter 9)
Chapter 9 describes the I/O signals used for parameter setting, the I/O signal
timing charts, and program examples.
(10) Operations on MODBUS device data performed by sequence
programs (Chapter 10)
Chapter 10 describes the dedicated instructions used to perform read/write and
other operations on MODBUS device data performed by sequence programs.
(11) Error codes and corresponding corrective actions (Chapter 11)
(a) Section 11.1 describes the troubleshooting.
(b) Section 11.2 describes how to check the module condition.
(c) Section 11.3 describes the error code storage location and details.
(d) Section 11.4 describes how to turn OFF the COM.ERR. LED.
(e) Section 11.5 describes the PING test.
About the notation of the numerical values used in this manual
Among the numerical values used in this manual, "H" is placed to the right of the
units place for hexadecimal notation.
(Example) 10 ..... Decimal
10H... Hexadecimal

A-14 A-14
ABOUT THE GENERIC TERMS AND ABBREVIATIONS
Unless otherwise specified, this manual uses the following generic terms and
abbreviations to explain the QJ71MT91 MODBUS/TCP interface module.
Generic Term/Abbreviation Description
QJ71MT91 An abbreviation for the QJ71MT91 MODBUS/TCP interface module
MODBUS/TCP A generic term for the protocol designed to use MODBUS protocol messages on a
TCP/IP network
MODBUS serial protocol A generic term for the protocol designed to use MODBUS protocol messages on a
serial interface
FC An abbreviation for the function code
SC An abbreviation for the sub code
Programmable controller CPU A generic term for the Basic model QCPU, High Performance model QCPU, Process
CPU, Redundant CPU, Universal model QCPU
Basic model QCPU A generic term for the Q00JCPU, Q00CPU and Q01CPU
High Performance model
QCPU A generic term for the Q02CPU, Q02HCPU, Q06HCPU, Q12HCPU and Q25HCPU
Process CPU A generic term for the Q02PHCPU, Q06PHCPU, Q12PHCPU and Q25PHCPU
Redundant CPU A generic term for the Q12PRHCPU and Q25PRHCPU
Universal model CPU
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, Q100UDEHCPU
GX Developer The product name of the software package for the MELSEC programmable controllers
GX Works2
Ethernet module The QJ71E71-100 Ethernet interface module
Ethernet Address
A machine-specific address that is also referred to as the MAC (Media Access Control)
address. This is used to identify the addresses of external devices over a network.
The Ethernet address of the QJ71MT91 can be verified on the MAC ADD column of
the rating plate.
MELSECNET/H The MELSECNET/H network system
Master The side from which a request is sent to execute a function
Slave The side where the execution request from the master is processed and its execution
result is sent
Master function The function that allows communication with the MODBUS/TCP compatible slave
device as the master of MODBUS/TCP
Slave function The function that allows communication with the MODBUS/TCP compatible master
device as the slave of MODBUS/TCP
Request message
The message used to give a function execution request to the slave.
In the MODBUS protocol, a function execution request is given from the master to the
slave.
A function execution request cannot be given from the slave to the master.
Response message The message with which the slave returns a function execution result to the master
Target device
A generic term for the communication targets (such as a personal computer, other
QJ71MT91 MODBUS/TCP interface module, and MODBUS protocol compatible
device) connected for data communication.
Personal computer The IBM PC/AT or compatible DOS/V-based personal computer
MBRW The abbreviation for Z.MBRW or ZP.MBRW
MBREQ The abbreviation for Z.MBREQ or ZP.MBREQ

A-15 A-15
Generic Term/Abbreviation Description
Windows 7
A generic term for Microsoft Windows 7 Starter operating system, Microsoft
Windows 7 Home Premium operating system, Microsoft Windows 7 Professional
operating system, Microsoft Windows 7 Ultimate operating system, and Microsoft
Windows 7 Enterprise operating system
Note that the 32-bit version is specified as "32-bit Windows 7", and the 64-bit version
is specified as "64-bit Windows 7".
Windows Vista
A generic term for Microsoft Windows Vista Home Basic operating system, Microsoft
Windows Vista Home Premium operating system, Microsoft Windows Vista Business
operating system, Microsoft Windows Vista Ultimate operating system, and Microsoft
Windows Vista Enterprise operating system
Windows XP A generic term for Microsoft Windows XP Professional operating system, and Microsoft
Windows XP Home Edition operating system
MEANINGS AND DEFINITIONS OF TERMS
The following explains the meanings and definitions of the terms used in this manual.
Term Meaning/Definition
MODBUS device Device used for communication using the MODBUS protocol
Sequence program
Programming system devised to make a contact type sequence compatible with the
programmable controller language as-is. Draw two vertical control buses and describe
contacts or others between the buses to perform programming.
Device memory Memory provided for the programmable controller CPU to record the data handled in
sequence program operation
PRODUCT CONFIGURATION
The following indicates the product configuration of the QJ71MT91 MODBUS/TCP
interface module.
Model Item name Quantity
QJ71MT91 QJ71MT91 MODBUS/TCP interface module 1
SW1D5C-QMBU-E GX Configurator-MB Version 1 (1-license product) (CD-ROM) 1
SW1D5C-QMBU-EA GX Configurator-MB Version 1 (Multiple-license product) (CD-ROM) 1
R
R R R
R R R
R R R
R
R
R
R
R R R
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MELSEC-Q
1 OVERVIEW
1 OVERVIEW
This manual explains the specifications, functions, programming, troubleshooting, and
others of the MELSEC-Q series QJ71MT91 MODBUS/TCP interface module
(hereafter abbreviated to the QJ71MT91).
The QJ71MT91 is used to connect the MELSEC-Q series programmable controller to
a MODBUS/TCP network.
1.1 Features
(1) Supporting master function of MODBUS/TCP communication
The QJ71MT91 supports the master function of MODBUS/TCP communication,
which is an open network system for factory automation, and it is compatible with
various MODBUS/TCP slave devices (hereafter abbreviated to the slaves) of
other manufactures.
The master function supports the following two functions.
(a) Automatic communication function
By setting the automatic communication parameters, MODBUS device data
can be automatically read from or written to the slaves at the specified
intervals using the QJ71MT91 buffer memory. ( 1)
Data can be transferred between the QJ71MT91 buffer memory and
programmable controller CPU device memory by making the auto refresh
setting with the utility package (GX Configurator-MB) or accessing a
intelligent function module device with a sequence program.
1: The MODBUS device indicates the device area of the slave where data can be read/written in response
to a request from the master.
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MELSEC-Q
1 OVERVIEW
(b) Communication using dedicated instruction
Dedicated instructions can be used to make communication from a
sequence program at any timing.
The QJ71MT91 supports the following two dedicated instructions.
1) MBRW instruction
Reads/writes MODBUS device data from/to a slave.
This enables slave data to be read out to the programmable controller
CPU device memory or programmable controller CPU data to be
written to the slave.
2) MBREQ instruction
Can issue user-desired request message format (function code 1 +
data unit) to a slave.
1: Refer to Chapter 4 for the function code.
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MELSEC-Q
1 OVERVIEW
(2) Supporting slave function of MODBUS/TCP communication
The QJ71MT91 supports the slave function of MODBUS/TCP communication,
which is an open network system for factory automation, and it is compatible with
various MODBUS/TCP master devices (hereafter abbreviated to the masters) of
other manufacturers.
The slave function supports the following two functions.
(a) Automatic response function
The QJ71MT91 can automatically respond to a request message received
from the master.
A sequence program for the slave function is not needed.
(b) MODBUS device assignment function
Using MODBUS device assignment parameters, the MODBUS devices are
correlated with the programmable controller CPU device memory.
This enables direct access from the master to the programmable controller
CPU device memory.
Supporting the MODBUS devices of large capacity, the QJ71MT91 allows
all device memory areas of the programmable controller CPU to be
assigned.