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Siemens S7-1200 “Modbus RTU” LS iG5A VFD Tutorial

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Controlling multiple inverters in one plant, or controlling
and remote inverter parameter monitoring is a problem we often encounter. Therefore, the inverters are usually equipped with RS485 port to support Modbus RTU communication (supports 1 control network up to 32 slaves and 1200m distance).

Today will guide you to use the Siemens S7-1200 PLC to control the LS iG5A inverter via Modbus-RTU communication.

Connection Diagram

Communication Configuration LS iG5A VFD

Communication parameters we need to set

The parameters I set in the project:

+ Drv = 3

+ Frq = 7

+ I59 = 0

+ I60 = 1

+ I61 = 3

+ I62 = 0

+ I65 = 2

Register Address Table

S7-1200 Comm. Configuration ( CB1241 Module)

I recommend you choose the transmission type: 9600bps/8bits/Even


PLC Programming

+ Communication Distribution

+ Communication Load Command

+ Frequence Set Command

+ Motor Control Run Command

+ Read Output Data Response

Video Connecting S7-1200 and LS iG5A



So today I have guided you on how to connect S7-1200 and LS iG5A VFD in detail, if you have any questions, please comment below the article, I will answer as soon as I read it.

Best Regards!

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  • Hi,
    I am using s7-1200 PLC with CB1241 to communicate with “5” VFDs { 4 VFDs of Type LSLV-S100 and the last one is SV-iS7} where all are of the LSIS brands.
    I made the configuration and can read and write from the VFDs when all machines are off. When machines and motors are running, the Commands are delayed to 5 and sometimes 10 minutes.
    I think this is due to parasites in the environment. How can I overcome this issue?
    Is there another reason that can lead to this malfunctioning other than parasite ( knowing that when all machines are off and nothing is running, the communication is OK.

  • excuse me sir
    VFD Control Address = table (hex) = table (dec) + 40001 = (dec)
    why did you substract 1 from the table address i have seen in anthor examble you add the table address to 40001?

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