Modbus and TCP protocols are different, but they are also closely connected. The combine of the two protocols is based on Modbus/TCP/IP protocol remote network communication, which prompts the usage of Modbus in the equivalents applications.

Modbus protocol is mainly used in electrical automation and process control, which adopts RS232 and RS485 interfaces. The disadvantages of Modbus protocol are short distance and slow transmission speed, because of that, a lot of applications were restricted. TCP/IP protocol is mainly used in the Application of the Internet, the advantages of TCP/IP are long transmission distance and fast transmission speed, the applications of TCP/IP protocol are wider.

1、Modbus protocol

Modbus protocol is a universal language that used in electrical automation electronic controllers. This protocol allows controllers as well as other network devices to communicate with each other, and it became an industry-standard protocol. Modbus protocol has good interactivity and open standards and has been widely used in the industrial field.

Modbus has two communication modes: ASCII and RTU, Modbus-RTU(Modbus Remote Terminal Unit) and Modbus-ASCII(American Standard Code for Information Interchange). Although there are two communication modes, only one communication mode can be selected when using, and mixed-use is not supported.

 2. TCP/IP Protocol

TCP/IP Protocol is short for Transmission Control Protocol/Internet Protocol，which is a complete set of network protocols over the physical network. The role of TCP is to provide the transport layer services, and the role of IP is to provide network layer services. The core part of the TCP / IP protocol is the transport layer protocol (TCP / UDP), the network layer protocol (IP), and the physical interface layer.

How to configure Modbus TCP of serial to Ethernet converter, please click: https://www.usriot.com/support/faq/configure-modbus-tcp-of-serial-to-ethernet-converter.html,

For details, please refer to the documentation in this link: https://www.usriot.com/download/M4/Modbus-Gateway-Manual-of-Industrial-M4-Serial-to-Ethernet_V1.0.0.pdf