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Siemens S7 1200 “Modbus RTU” Omron E5CC Tutorial

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S7-1200 provides a PROFINET port, supports Ethernet and TCP/IP standards along with RS232/485 communication modules, it is really an ideal PLC for factory IoT.

Today would like to share with you how to control and read temperature from Omron E5CC thermostat via Modbus-RTU RS485, supporting up to 32 stations with a distance of 1200m

Wiring Diagram Siemens S7-1200 and Omron E5CC

Please wire according to the diagram below, use a twisted pair and use a terminal resistor (120 Ohm) if the communication distance is long.

Communication Configuration Omron E5CC

Table of communication parameters and configuration in the project

Modbus Register

+ PV (Present Value) = 2000 (hex) = 8192 (dec)
>>> Modbus Address on Tia Portal = 40001 + 8192 = 48193 (dec)

+ SV (Set Value) = 2103 (hex) = 8451 (dec)
>>> Modbus Address on Tia Portal = 40001 + 8451 = 48452 (dec)

Communication Configuration S7-1200 CB1241 RS485 Modules

In the project I use S7 1200 in combination with Modules CB-1241 (Module CM-1241 is similar).

S7-1200 PLC Programming

+ Read and Write Distribution

+ Communication Configuration

+ E5CC #1 SV Write

+ E5CC #2 SV Write

+ E5CC #1 PV Read

+ E5CC #2 PV Read

Detailed Instruction Video


So has finished showing you how to connect PLC Siemens S7-1200 and Omron E5CC. If you have any questions, please comment below the article, I will answer you as soon as possible.

Thanks and Best Regards!

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