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Mitsubishi QJ71C24N “Modbus RTU” Danfoss FC302 Tutorial

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Danfoss VLT® Automation Drive FC 302 inverter: Applied in automatic lines such as food and beverage processing such as mixers, stirrers, crushers, conveyors, conveyors, fans, cranes, etc. Power up to 1400 Kw.

Danfoss FC302 inverter is designed to be compact but powerful, compatible with all communication standards: Profibus, DeviceNet, CanOpen, Profinet, Ethernet IP, Modbus TCP… Today will guide you to use Mitsubishi Q-Series PLC in combination with QJ71C24N Module to control Danfoss FC302 inverter through Modbus-RTU communication protocol

QJ71C24N & Danfoss FC302 “Connection Diagram”

Danfoss FC302 inverter is equipped with an RS485 communication port at pins (68, 69). You can connect to Module QJ71C24N according to the diagram below:

Danfoss FC302 “Modbus RTU” Parameters Setting

Below are the communication parameters that we need to install for Danfoss FC302 to make it controllable and monitored using Modbus RTU protocol:

Danfoss FC302 Modbus Registers Address

>>> VFD Control Command = C34F (hex)

  • Set Word C34F = 47C (hex) >>> Run Forward
    = 847C (hex) >>> Run Reverse
  • Set Word C34F = 43C (hex) >>> Stop
  • Set Word C34F = 4BC (hex) >>> VFD Reset

>>> Speed Reference Address = C359 (hex)
+ Speed Reference = “0 to 16384dec” = “0 to 100%”

+ Voltage Output Address = 16119 (dec)
+ Frequency Output Address = 16129 (dec)
+ Current Output Address = 16139 (dec)
+ Speed Output Address = 16169 (dec)

Mitsubishi QJ71C24N “Modbus RTU” Configuration

Please follow these steps to configure the Communication Module QJ71C24N:

+ Step 1: Create Project

+ Step 2: In/Out Configuration

+ Step 3: QJ71C24N Parametes Setting

+ Step 4: Sent parameters to Module

+ Step 5: “Echoback Dissable”

  • Echoback refers to the function in which data transmitted by RS-485 (2-wire) is returned about the local station’s RDA and RDB.
  • Echoback refers to the function in which data transmitted by RS-485 (2 wires) is returned about the local station’s RDA and RDB.
  • Set G450 = 1 (Disable Echoback) / = 0 (Enable Echoback)
QJ71C24N & Danfoss FC302 “Modbus RTU” Configuration

+ “Serial Communication Module…” setting

+ Add/Read/Write Protocol

Protocol Mapping

+ Protocol No.1: “Func = 06 / Write Single Registers”

  • Slave Address = D100
  • Register Adress = D101
  • Register Value = D110
  • “Comm. Error” = D300

+ Protocol No.2: “Func = 03 / Read Holding Registers”

  • Slave Address = D200
  • Starting Address = D201
  • Quantity of Registers = D202
  • Registers Value Response = D210 (From D210…D335 depending on the number of Registers (D202) to read)
  • “Comm. Error” = D300

Important: Need to set “Receive Wait Time”, if Set = 0, error communication will be “Infinite Wait”

QJ71C24N Modbus Example

+ Disable “Echoback” & Error Clear

+ Read/Write Distribution

+ Frequency Setting Command

+ Motor Control Command

+ Read Data Monitoring

+ HMI Interface

Detailed Instruction Video


Related Software and Documents
+ Mitsubishi GX-Works 2 Software Free Download
+ Mitsubishi Q03UDV & Weintek HMI “Connection Tutorial”
+ Danfoss FC302 Manual PDF Free Download

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