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[Tutorial] Keyence KV-L21V & FR-E720 VFD “Modbus RTU”

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Hello friends, Modbus-RTU is a standard that has been around for a long time but is still widely used today in many machines and factories.

The advantages of Modbus-RTU are low cost, control of up to 32 stations with only one Master, large communication distance (up to 1200m).

Today will guide you to control Mitsubishi FR-E720 inverter by KEYENCE PLC (KV-L21V module) via Modbus-RTU (RS485-2 wire) communication.

Connection diagram KV-L21V and FR-E720

Setting VFD Parameters FR-E720

This is a table showing the parameters of the FR-E720 when using Modbus-RTU mode

>>> For this project please set the parameters below

  • Pr117 : “1” (Slave.1)
  • Pr118 : “9600” (Baud rate)
  • Pr119 : “0” (8bit/Stop bit.1)
  • Pr120 : “2” (Even bit)
  • Pr121 : “9999”
  • Pr122 : “9999”
  • Pr123 : “9999”
  • Pr124 : “1”
  • Pr340 : “1”
  • Pr549 : “1”
  • Pr79 : “6” ( External Mode > Last Setting )

Mitsubishi FR-E720 Register Address Table

Starting address: Starting register address (decimal)-40001

The addresses used in the program:

  • Running Frequency: 13 (Hex “D”)
  • Inverter status/control input: 8 (Hex “8”)
  • Output Frequency: 200 (Hex “C8”)
  • Output Current: 201 (Hex “C9”)
  • Output Voltage: 202 (Hex “CA”)

PLC Keyence Setting

PLC Programming

Delete Port2 Data storage unit

Transmission Distribution

Frequency Write

Control Run

Response Data Read

Read Data Output

Detailed Connection Instruction Video


So has finished showing you how to connect PLC Keyence to VFD Mitsubishi, basically PLC Keyence does this very easily. If you need any help, feel free to comment below

Best Regards

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