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Writing data to the server using Modbus TCP/IP


ronaldotukchro Nov 18, 2025 07:57 PM

Hi, I have a sensor that outputs three variables, and I need to write those three variables to a server using Modbus TCP/IP. I would do this with the ModbusMaster() instruction, but where would I configure the server's IP address? TCPOpen?
Could someone help me?


JDavis Nov 18, 2025 11:29 PM

Use TCPOpen() to open the connection. Use the socket number returned by TCPOpen for the comport in ModbusMaster().


JamesOrr Nov 24, 2025 06:18 AM

Writing data over Modbus TCP/IP can feel confusing at first, but the idea is simple: the server waits for specific register writes, and the client pushes values to those addresses. The main challenge is making sure both sides agree on register mapping and data format. If the mapping is off, the server receives the request but nothing changes. Once the addresses and function codes match, the communication becomes steady and predictable. It’s one of those setups where a small configuration detail can make the whole system finally click.

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