Contents

SAFETY PRECAUTIONS
CONDITIONS OF USE FOR THE PRODUCT
REVISIONS
INTRODUCTION
CONTENTS
COMPLIANCE WITH EMC AND LOW VOLTAGE DIRECTIVES
THE MANUAL'S USAGE AND STRUCTURE
ABOUT THE GENERIC TERMS AND ABBREVIATIONS
MEANINGS AND DEFINITIONS OF TERM
PRODUCT CONFIGURATION
CHAPTER1 OVERVIEW
- 1.1 Features
CHAPTER2 SYSTEM CONFIGURATION
- 2.1 Applicable Systems
- 2.2 Network Configuration
- 2.3 Precautions for System Configuration
- 2.4 How to Check the Function Version/Software Version
CHAPTER3 SPECIFICATIONS
- 3.1 Performance Specifications
- 3.2 RS-232 Interface Specification
  - 3.2.1 RS-232 connector specification
  - 3.2.2 RS-232 cable specification
- 3.3 RS-422/485 Interface Specification
  - 3.3.1 RS-422/485 terminal block specification
  - 3.3.2 RS-422/485 cable specification
  - 3.3.3 Precautions when transferring data using RS-422/485 line
- 3.4 I/O Signals for Programmable Controller CPU
  - 3.4.1 I/O signal list
- 3.5 Applications and Assignment of Buffer Memory
  - 3.5.1 Buffer memory list
CHAPTER4 MODBUS STANDARD FUNCTIONS
- 4.1 MODBUS Standard Function Support List
- 4.2 Frame Specifications
  - 4.2.1 Frame mode
- 4.3 Protocol Data Unit Formats by Functions
- 4.4 Read Coils (FC: 01)
- 4.5 Read Discrete Inputs (FC: 02)
- 4.6 Read Holding Registers (FC: 03)
- 4.7 Read Input Registers (FC: 04)
- 4.8 Write Single Coil (FC: 05)
- 4.9 Write Single Register (FC: 06)
- 4.10 Read Exception Status (FC: 07)
- 4.11 Diagnostics (FC: 08)
  - 4.11.1 Return query data (sub-function code: 00)
  - 4.11.2 Restart communications option (sub-function code: 01)
  - 4.11.3 Return diagnostic register (sub-function code: 02)
  - 4.11.4 Change ASCII input delimiter (sub-function code: 03)
  - 4.11.5 Force listen only mode (sub-function code: 04)
  - 4.11.6 Clear counters and diagnostic register (sub-function code: 10)
  - 4.11.7 Return bus message count (sub-function code: 11)
  - 4.11.8 Return bus communication error count (sub-function code: 12)
  - 4.11.9 Return bus exception error count (sub-function code: 13)
  - 4.11.10 Return slave message count (sub-function code: 14)
  - 4.11.11 Return slave no response count (sub-function code: 15)
  - 4.11.12 Return slave NAK count (sub-function code: 16)
  - 4.11.13 Return slave busy count (sub-function code: 17)
  - 4.11.14 Return bus character overrun count (sub-function code: 18)
  - 4.11.15 Return IOP overrun error count (sub-function code: 19)
  - 4.11.16 Clear overrun counter and flag (sub-function code: 20)
- 4.12 Get Communications Event Counter (FC: 11)
- 4.13 Get Communications Event Log (FC: 12)
- 4.14 Write Multiple Coils (FC: 15)
- 4.15 Write Multiple Registers (FC: 16)
- 4.16 Report Slave ID (FC: 17)
- 4.17 Read File Record (FC: 20) (SC: 06)
- 4.18 Write File Record (FC: 21) (SC: 06)
- 4.19 Mask Write Register (FC: 22)
- 4.20 Read/Write Multiple Registers (FC: 23)
CHAPTER5 FUNCTIONS
- 5.1 Function List
- 5.2 Master Function
  - 5.2.1 Automatic communication function
  - 5.2.2 Communication by dedicated instructions
- 5.3 Slave Function
  - 5.3.1 Automatic response function
  - 5.3.2 MODBUS device assignment function
  - 5.3.3 Link operation function
CHAPTER6 PRE-OPERATIONAL PROCEDURES AND SETTINGS
- 6.1 Handling Precautions
- 6.2 Pre-Operational Procedures and Settings
- 6.3 Part Names
- 6.4 Unit Tests
  - 6.4.1 Hardware test
  - 6.4.2 Self-loopback test
- 6.5 Connection to a Target Device
  - 6.5.1 How to connect the RS-232 interface
  - 6.5.2 How to connect the RS-422/485 interface
- 6.6 Intelligent Function Module Switch Setting
- 6.7 Maintenance, Inspection
  - 6.7.1 Maintenance, inspection
  - 6.7.2 When removing or installing the module
CHAPTER7 PARAMETER SETTING
- 7.1 Parameter Settings and Setting Procedure
- 7.2 Automatic Communication Parameter
  - 7.2.1 Automatic communication parameter details
- 7.3 MODBUS Device Assignment Parameter
  - 7.3.1 MODBUS device assignment to the programmable controller CPU device memory
  - 7.3.2 MODBUS extended file register assignment to the programmable controller CPU file register
  - 7.3.3 QJ71MB91 buffer memory assignment
  - 7.3.4 Specifying the error status read device
  - 7.3.5 Specifying access target when mounted to MELSECNET/H remote I/O station
  - 7.3.6 Specifying the CPU response monitoring timer
CHAPTER8 UTILITY PACKAGE (GX Configurator-MB)
- 8.1 Functions of the Utility Package
- 8.2 Installing and Uninstalling the Utility Package
  - 8.2.1 Handling precautions
  - 8.2.2 Operating environment
- 8.3 Utility Package Operation
  - 8.3.1 Common utility package operations
  - 8.3.2 Operation overview
  - 8.3.3 Starting the Intelligent function module utility
- 8.4 Initial Setting
  - 8.4.1 Automatic communication parameter
  - 8.4.2 MODBUS device assignment parameter
- 8.5 Auto Refresh Setting
- 8.6 Monitor/Test
  - 8.6.1 X/Y Monitor/test
  - 8.6.2 MODBUS device assignment parameter status
  - 8.6.3 Automatic communication status
  - 8.6.4 Error log
  - 8.6.5 Communication status
CHAPTER9 PROGRAMMING
- 9.1 Parameter Setting
  - 9.1.1 Automatic communication parameters
  - 9.1.2 MODBUS device assignment parameters
- 9.2 Program Example for Normal System Configuration
  - 9.2.1 Automatic communication parameters
  - 9.2.2 MODBUS device assignment parameters
  - 9.2.3 When using the automatic communication function and the communication by dedicated instructions on the same channel
- 9.3 Program Examples for Use in MELSECNET/H Remote I/O Network
  - 9.3.1 Automatic communication parameters
  - 9.3.2 MODBUS device assignment parameters
- 9.4 Program Examples for the Redundant System
CHAPTER10 DEDICATED INSTRUCTIONS
- 10.1 Dedicated Instruction List and Available Devices
- 10.2 Z(P).MBRW
- 10.3 Z(P).MBREQ
- 10.4 ZP.UINI
CHAPTER11 TROUBLESHOOTING
- 11.1 Troubleshooting
- 11.2 Checking QJ71MB91 Status
- 11.3 Checking the Communication Status of QJ71MB91
- 11.4 Error Codes
  - 11.4.1 Error code storage area
  - 11.4.2 Exception code list
  - 11.4.3 Error code list
- 11.5 Turning Off the ERR. LED
  - 11.5.1 Turning off the ERR. LED by GX Configurator-MB
  - 11.5.2 Turning off the ERR. LED by sequence program
  - 11.5.3 Turning off the ERR. LED by request message from the master
APPENDICES
- Appendix 1 Function Upgrade of the QJ71MB91
- Appendix 2 A Series Modules
  - Appendix 2.1 Comparisons in performance specifications
  - Appendix 2.2 Functional comparisons
  - Appendix 2.3 Utilization of existing programs
- Appendix 3 Processing Time
- Appendix 4 External Dimensions
INDEX
WARRANTY

Mitsubishi Electric MELSEC Q QJ71MB91 User's Manual

Mitsubishi Electric MELSEC Q QJ71MB91 manual cover

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Mitsubishi Electric MELSEC Q QJ71MB91 Specification

The Mitsubishi Electric MELSEC Q Series QJ71MB91 is a high-performance Modbus Plus network interface module designed to integrate seamlessly within the MELSEC Q Series PLC systems. This module is engineered to facilitate efficient communication between the MELSEC Q Series CPU and Modbus Plus devices, offering a robust solution for industrial automation systems requiring reliable data exchange. The QJ71MB91 supports the Modbus Plus protocol, enabling connectivity with a wide array of devices such as HMIs, remote I/O modules, and various field devices that utilize this widely-recognized communication standard.

The module features a single Modbus Plus network port, allowing it to connect to a Modbus Plus network operating at a speed of 1 Mbps. It is capable of supporting up to 32 nodes per network, providing ample connectivity for complex systems. The QJ71MB91 facilitates cyclic data exchange and supports both master and slave functionality, ensuring flexible integration options within diverse network architectures. Its design incorporates advanced diagnostic capabilities, enabling users to efficiently monitor network status and troubleshoot communication issues.

The module is designed to fit seamlessly into the Q Series base rack, utilizing the same compact and modular design principles that characterize the MELSEC Q Series. This ensures easy installation and scalability, allowing users to expand their systems with minimal effort. Additionally, the QJ71MB91 is equipped with a range of status indicators and configuration options accessible via the MELSOFT software suite, facilitating efficient setup and operation within industrial environments. Overall, the Mitsubishi Electric MELSEC QJ71MB91 offers a reliable and adaptable networking solution for integrating Modbus Plus devices into modern automation systems.

Mitsubishi Electric MELSEC Q QJ71MB91 F.A.Q.

How do I configure the QJ71MB91 module for Modbus communication?

To configure the QJ71MB91 module for Modbus communication, set up the communication parameters using GX Works2 or GX Developer. Define the station number, baud rate, parity, and other relevant settings in the network parameters. Ensure the module is inserted in the correct slot and the correct dip switches are set.

What are the primary troubleshooting steps if the QJ71MB91 module is not communicating?

First, verify the physical connections and ensure the cables are correctly attached. Check the LED indicators on the module for error codes. Use the diagnostics tools in GX Works2 to identify configuration errors. Ensure that the Modbus addresses and parameters match those of the connected devices.

How can I update the firmware of the QJ71MB91 module?

To update the firmware, download the latest firmware version from the Mitsubishi Electric website. Connect to the module using GX Works2, and follow the instructions provided in the firmware update guide to transfer and install the new firmware. Ensure all data is backed up before proceeding.

What maintenance is required for the QJ71MB91 module?

Regularly check and clean the module to prevent dust accumulation which can impact performance. Inspect the module connections and cables for wear or damage. Ensure the firmware is up-to-date and periodically review the configuration settings for any necessary adjustments.

How do I set up a QJ71MB91 module to act as a Modbus master?

In the GX Works2 software, configure the QJ71MB91 as a master by setting the operating mode to 'Master'. Define the slave devices and their parameters under the network configuration. Ensure that the master settings match the communication requirements of the slave devices.

Can the QJ71MB91 module be used with third-party Modbus devices?

Yes, the QJ71MB91 module can be used with third-party Modbus devices. Ensure that the communication parameters such as baud rate, parity, and data bits are compatible. Configure the Modbus addresses and functions to match the third-party devices.

What should I do if the QJ71MB91 module shows a communication timeout error?

Check the network cables and connections for any issues. Verify that the slave devices are powered on and correctly configured. Adjust the timeout settings in the QJ71MB91 configuration to accommodate the network conditions.

How do I integrate the QJ71MB91 module into an existing MELSEC Q series system?

Insert the QJ71MB91 module into an available slot in the MELSEC Q series rack. Use GX Works2 to configure the module in the existing project. Update the network parameters to include the module and adjust any necessary settings to integrate it with the existing system.

What are the common causes of data transmission errors in the QJ71MB91 module?

Common causes include incorrect configuration settings, physical connection problems, incompatible communication parameters, and electromagnetic interference. Review the setup and use diagnostic tools to pinpoint the source of errors.

Is it possible to use the QJ71MB91 module with a wireless network?

While the QJ71MB91 module itself does not support wireless communication, it can be integrated into a system that includes wireless devices by using a wireless Modbus gateway. Ensure that the gateway is compatible and properly configured to relay data between the QJ71MB91 and the wireless network.