What is the difference between Modbus TCP and Modbus RTU?

The main differences between Modbus TCP and Modbus RTU are as follows:
1. Physical Layer: Modbus RTU is typically implemented over serial communication links such as RS-485, while Modbus TCP uses Ethernet as the physical layer for network communication.
2. Communication Protocol: Modbus RTU uses a serial binary transmission format with specific start and stop bits. Modbus TCP, on the other hand, operates on the TCP/IP protocol stack and encapsulates Modbus messages within TCP packets.
3. Error Checking: Modbus RTU often employs cyclic redundancy check (CRC) for error detection, while Modbus TCP relies on the error-checking mechanisms provided by the TCP protocol.
4. Bandwidth and Speed: Due to the nature of Ethernet, Modbus TCP can offer higher data transfer speeds and larger bandwidth compared to serial-based Modbus RTU.
5. Network Topology: Modbus RTU is often used in simple point-to-point or multi-drop serial networks, while Modbus TCP is suitable for more complex Ethernet-based networks with multiple devices connected.
6. Configuration and Setup: Configuring a Modbus TCP network typically involves IP addressing and network settings, while Modbus RTU requires setting serial communication parameters like baud rate, parity, and stop bits.
In summary, the choice between Modbus TCP and Modbus RTU depends on the specific requirements of the application, the available communication infrastructure, and the performance and functionality needed.