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Entry type: FAQ Entry ID: 94766380, Entry date: 07/05/2017
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How do you program and parameterize Modbus/TCP communication between two S7-1500 CPUs?

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To establish Modbus/TCP communication between two S7-1500 CPUs you call the "MB_CLIENT" and "MB_SERVER" instructions in the user program of the S7-1500 CPUs.

The "MB_CLIENT" instruction communicates as Modbus/TCP client via the PROFINET connection. You use the "MB_CLIENT" instruction to establish a connection between the client and the server, send Modbus requests and receive responses, and control the connection disconnection of the Modbus/TCP client.

The "MB_SERVER" instruction communicates as Modbus/TCP server via a PROFINET connection. The "MB_SERVER" instruction processes connection requests of a Modbus/TCP client, receives and processes Modbus requests and sends response messages.

The application example and the instructions in Entry 102020340show how to call and parameterize the "MB_SERVER" and "MB_CLIENT" instructions in the user program of the S7-1500 CPU.

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