Modbus RTU
Modbus RTU is a serial communication protocol based on RS‑485 hardware interface.
It uses binary coding for high efficiency.
Typical baud rates: 9600, 19200, 38400, 57600, 115200 bps.
Master‑slave architecture: one master, multiple slaves.
Communication distance: up to 1200 meters (with RS‑485 repeater).
Common applications: field instruments, sensors, PLCs, level meters, flow meters.
Advantages:
Simple wiring, low cost
Stable in industrial field environments
Widely supported by industrial instruments
Disadvantages:
Short communication distance
Low speed compared to Ethernet
Not suitable for large‑scale network systems
Modbus TCP
Modbus TCP is an Ethernet‑based Modbus protocol that runs over TCP/IP.
Uses standard Ethernet (RJ45) interface.
Communication via standard TCP port: 502.
High speed, long distance, and expandable via switches/routers.
Can connect many devices over a network.
Advantages:
High communication speed
Long transmission distance
Easy to integrate with SCADA, DCS, and upper computers
Suitable for large‑scale and remote monitoring
Disadvantages:
Higher hardware cost
Requires network configuration (IP, subnet, gateway)
Comparison Summary
Modbus RTU: Serial (RS485), short distance, low cost, widely used in field instruments.
Modbus TCP: Ethernet, high speed, long distance, used in industrial networks and upper systems.
Post time: Mar-17-2026