Modbus RTU vs Modbus TCP - which to use?
Selection Q&A Updated
RTU runs on RS-485 serial - simple wiring, cheap devices, fine for local small-scale acquisition. TCP runs on Ethernet - faster, routable, IT-friendly. Retrofits typically use a gateway to bridge legacy RTU devices to TCP/MQTT.
Modbus RTU is a serial protocol on RS-485 - one twisted pair daisy-chains dozens of meters at minimal cost, but speed is limited and debugging is an art. Modbus TCP moves the same register model onto Ethernet: faster, routable and directly readable by platform software.
Real projects use both: legacy meters speak RTU, new remote I/O (like the ADAM-6017) speaks TCP/MQTT natively, and a gateway or protocol-converting router bridges them into one platform. KIES quotes acquisition solutions on this structure by default.