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Siemens S7-1200 “Modbus RTU” PowerFlex525 VFD

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Hello everyone.
PLC Siemens S7-1200 and Inventer PowerFlex525 are two devices that are used a lot in European and American machines. Its quality is not to say much, and today will guide you to connect them together. uses the Modbus-RTU communication standard. We need to use an additional RS485 expansion module, which is S7-1200 CB1241 (or S7-1200 CM1241) to connect to PowerFlex525.

S7-1200 & PowerFlex525 “Wiring Diagram”

Power Flex525 VFD Modbus-RTU Settings

In order for the inverter to be controlled by Modbus RTU, we need to configure the following parameters

Motor Control Register Address

>>> Control Address = 40001 (dec) + 8192 (dec) = 48193

+ Set Word 48193 = 0000.0000.0001.0010 = 18 (dec) >>> Motor Forward Run
= 0000.0000.0010.0010 = 34 (dec) >>> Motor Reverse Run
= 0000.0000.0000.0001 = 1 (dec) >>> Motor Stop

>>> Frequency Setting Address = 40001 (dec) + 8193 (dec) = 48194

Monitoring Register Address

Siemens S7-1200 Modbus-RTU Settings

Configuration Module S7-1200 CB1241

Create PLC Data Types

Create Data Block

S7-1200 Modbus-RTU Programming

+ Read and Write Distribution

+ Communication Configuration

+ Frequency Setting Command

+ Motor Control Command

+ Data Monitoring Read

Detailed Installation Instruction Video


Required software and documentation:

+ TIA Portal Software for S7 1200 Programming
+ Allen-Bradley PowerFlex 525 Manual PDF

Password Extract:

If you need assistance with any problem in using PLC S7-1200 to control PowerFlex525 VFD, please comment below the article.

Thanks and Best Regards!

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