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Entry type: FAQ, Entry ID: 109479369, Entry date: 05/10/2016

How do you use the Modbus block "MODBUSPN" to communicate with multiple Modbus devices via a connection resource of the CPU?

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Data is to be exchanged between a PN CPU and multiple communication partners via Modbus/TCP. The CPU has a limited number of connection resources for this.

Simultaneous communication with all partners is not possible if the number of Modbus/TCP communication partners exceeds the number of available communication resources. However, you can still realize communication by multiplexing the connections.

The document below describes how to use just one connection resource of the PROFINET CPU to read data from multiple communication partners via Modbus/TCP.

109479369_ModbusTCP_Communication_v10_en.pdf (2.3 MB)

The download includes the project "109479369_Modbus_TCP.zip".
Unpack the "109479369_Modbus_TCP.zip" file in a separate directory. Then you can use STEP 7 to open and edit the project.

Registration required109479369_ModbusTCP_Communication_v10.zip (279,4 KB)

Creation Environment
The screens and downloads in this FAQ response were created with STEP 7 V5.5 SP4.

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