best regards

Even though all four MB_CLIENTs are targeting the same IP (192.168.0.10), each one can communicate with a different Modbus slave ID over that IP. In Modbus TCP, the Unit ID (or slave ID) is how the gateway distinguishes which RTU device you want to talk to behind it.

it will work, as long as:

All four MB_CLIENT instructions use the same IP address (192.168.0.10) and port 502, but target different Modbus slave IDs (1, 2, 3, 4).

Your Moxa MB3180 is properly configured to forward each Unit ID to the corresponding RTU device.

Thank you. You have given me confidence ))