Mitsubishi QJ71C24N Modbus RTU Communication with Delta VFD-M

Mitsubishi QJ71C24N Modbus RTU Communication with Delta VFD-M Tutorial

Introduction

The Delta VFD-M inverter, once a popular choice in the market, has been discontinued and replaced by newer models such as the Delta MS300 and Delta VFD-L series. Despite its discontinuation, many existing systems still utilize the Delta VFD-M inverter due to its reliability and performance. One of the key features of the Delta VFD-M is its built-in RS485 communication port, which supports the Modbus RTU communication protocol. This tutorial provides a comprehensive guide on how to connect, control, and monitor the Delta VFD-M inverter using the Mitsubishi Q-Series PLC equipped with the QJ71C24N communication module.

1. Mitsubishi QJ71C24N & Delta VFD-M: Wiring Diagram

To establish communication between the Mitsubishi QJ71C24N module and the Delta VFD-M inverter, a proper wiring connection must be set up. The Delta VFD-M features an RS485 communication port, which can be easily connected using a standard desk phone jack (RJ11) connector.

Wiring Diagram for QJ71C24N and Delta VFD-M

Key Notes:

• RS485 Port: The RS485 port on the Delta VFD-M inverter allows for seamless integration with the QJ71C24N module, facilitating efficient data exchange.

2. Delta VFD-M Modbus Parameters Setting

Before controlling the Delta VFD-M inverter via Modbus RTU, specific communication parameters must be configured. These settings ensure that the inverter can properly interpret commands and respond to requests sent from the Mitsubishi QJ71C24N module.

Essential Modbus RTU Parameter Settings:

1. Pr00 = 03: Set Frequency control via RS485.
2. Pr01 = 04: Motor control via RS485.
3. Pr88 = 01: Modbus Slave Address = 1.
4. Pr89 = 01: Baud Rate = 9600bps.
5. Pr92 = 04: Modbus RTU Protocol (8-bit, stop bit = 1, Even parity).
6. Pr157 = 01: Select Modbus RTU for communication.

3. Delta VFD-M Registers Address

Understanding the register addresses is crucial for issuing the correct commands and retrieving accurate data from the Delta VFD-M inverter. Below are the key Modbus register addresses used for controlling and monitoring the inverter.

Modbus Register Addresses:

1. Motor Control Address: 2000 (Hex)
   • Forward Run: Set 2000 (Hex) = 0000.0000.0001.0010 (Bin) = 18 (Dec)
   • Reverse Run: Set 2000 (Hex) = 0000.0000.0010.0010 (Bin) = 34 (Dec)
   • Stop: Set 2000 (Hex) = 0000.0000.0000.0001 (Bin) = 1 (Dec)

Delta VFD-M Registers Address

• Setting Frequency Address: 2001 (Hex)
• Monitoring Registers:
  • Output Frequency Address: 2103 (Hex)
  • Output Current Address: 2104 (Hex)
  • DC-BUS Voltage Address: 2105 (Hex)
  • Output Voltage Address: 2106 (Hex)

Delta VFD-M Registers Address

4. Mitsubishi QJ71C24N Modbus RTU Configuration

The next step involves configuring the Mitsubishi QJ71C24N module for Modbus RTU communication with the Delta VFD-M inverter. This process includes setting up the communication parameters and writing them to the module.

Step-by-Step Configuration:

• Step 1: Create New Project
  • Begin by creating a new project tailored to your specific PLC model within the Mitsubishi PLC programming environment.

• Step 2: I/O Assignment
• • Assign the I/O settings to include the QJ71C24N module as part of your PLC system.

• Step 3: RS485 Parameters Setting
• • Configure the necessary parameters for RS485 communication, ensuring they match the settings of the Delta VFD-M inverter.

• Step 4: Write Parameters to Module
• • After configuring the parameters, write them to the QJ71C24N module to enable the configuration.

• Step 5: Disable Echoback
• • Echoback refers to a function where data transmitted via RS485 is returned to the local station. Disable this function as follows:
  • Setting G450 = 1 (Disable Echoback)
  • Setting G450 = 0 (Enable Echoback, if necessary)

5. QJ71C24N Modbus RTU Protocols Configuration

Once the module configuration is complete, the next step is setting up the Modbus RTU protocols that will be used to send and receive data between the QJ71C24N module and the Delta VFD-M inverter.

Configuration via Serial Communication Module Tool:

+Go to Serial Communication Module Tool

+ Protocol Add/Read/Write

• Protocol No.1: Write Single Registers (Func 06)
• • Slave Address: D100
  • Register Address: D101
  • Register Value: D110
  • Error Code: D300

• Protocol No.2: Read Holding Registers (Func 03)
• • Slave Address: D200
  • Starting Address: D201
  • Quantity of Registers: D202
  • Registers Value Response: D210 (Data read starts at D210 and continues depending on the number of registers specified in D202)
  • Error Code: D300

QJ71C24N Modbus RTU Protocol Configuration

6. QJ71C24N Modbus RTU Example Program

With the configuration set, you can now create a PLC program that will control the Delta VFD-M inverter using the QJ71C24N module. Below is an outline of the essential program components.

Example Program Overview:

• Disable Echoback & Error Clear:
  • Ensure that Echoback is disabled and any existing errors are cleared before initiating communication.

• Communication Distribution:
• • Manage communication tasks by distributing read/write commands as needed.

• Setting Frequency Command:
• • Send the frequency setting command to the Delta VFD-M inverter.

• VFD Control Command:
• • Execute control commands such as Forward Run, Reverse Run, or Stop based on operational requirements.

• Read Data Response:
• • Monitor the response from the Delta VFD-M inverter to ensure it is operating within the desired parameters.

• HMI Control Panel:
• • Implement an HMI control panel to provide a user-friendly interface for controlling and monitoring the Delta VFD-M inverter.

Conclusion

This detailed tutorial covers the essential steps for setting up and controlling a Delta VFD-M inverter using the Mitsubishi QJ71C24N module via the Modbus RTU protocol. The guide includes wiring diagrams, parameter configurations, and practical PLC programming examples to ensure a seamless integration process. Refer to the images provided throughout the tutorial for additional clarity and visual guidance.