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Mitsubishi FX3U “Modbus RTU” Danfoss FC51 Tutorial

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Hello friends!
In previous posts, showed you how to use a number of PLCs, HMIs and PC software to control Danfoss FC51 inverters via Modbus RTU (RS485).

Today would like to continue to guide you to use another type of PLC that is Mitsubishi FX3U (in combination with Communication Module FX3U-485ADP-MB) to control Danfoss FC302.

Mitsubishi FX3U & Danfoss FC51 “Wiring Diagram”

Note: A 120Ω terminal resistor should be used if the communication distance between PLC and VFD is long distance.

Danfoss VLT FC51 Modbus-RTU Setting

In order for the FX3U PLC to control the Danfoss FC51 with Modbus RTU, we need to set the following communication parameters for the VFD:

Danfoss FC51 Modbus Registers Control

>>> VFD Control Address = C34F (hex)

  • Set Registers C34F = 47C (hex) or 1148 (dec) >>> Forward Run
    = 847C (hex) or 33916 (dec) >>> Reverse Run
    = 43C (hex) or 1084 (dec) >>> Stop
    = 4BC (hex) or 1212 (dec) >>> VFD Reset

>>> VFD Frequency Setting Address = C359 (hex)

  • Reference Setting = 0 to 16384(dec) ~ (0 to 100%) ~ (0 to 60Hz in Project)
Danfoss FC51 Modbus Registers for Monitoring

+ Output Voltage Address = 16120 – 1 = 16119 (dec)

+ Output Frequency Address = 16130 – 1 = 16129 (dec)

+ Output Current Address = 16140 – 1 = 16139 (dec)

FX3U Modbus RTU Example

+ FX3U Channel 2 Communication Configuration

+ Distribution Read/Write

+ VFD Control Command

+ VFD Data Monitoring

Project Video Tutorial


Related Software and Documents

+ Download Mitsubishi GX Works2 Software

+ Danfoss FC51 Manual PDF Download (Password Extract:

Please comment and share the article to the community if you find it useful. If you need any assistance in connecting FX3U with Danfoss FC51, please comment below the article, will reply to you as soon as you read comments.

Best Regards!

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