Industrial Modbus Gateway is a protocol converter that supports the Modbus interface (RS232/485/422) and Modbus TCP. With the function of Modbus TCP to Modbus RTU, it can easily and conveniently centrally manage scattered serial devices and hosts through the network, and users can easily realize the connection between Modbus Ethernet devices and Modbus serial devices. Connect to the serial server through a network cable, realize the simultaneous full-duplex operation of multiple Modbus interfaces, and provide 1-channel, 2-channel, 4-channel, and 8-channel Modbus device access applications.
What is the Modbus?
Modbus is a bus protocol used in industrial fields. The Modbus communication protocol is commonly used in the communication of third-party devices, such as DCS reading data from PLC and data from smart meters (flow meters, analyzers, etc.). Usually divided into 3 types of data protocols, Modbus RTU and Modbus TCP/IP, Modbus ASCII.
Introduction of 3 communication protocols of Modbus
The Modbus protocol is divided into three communication modes: Modbus RTU, Modbus ASCII, and Modbus TCP.
The communication format of Modbus TCP is similar to that of Modbus RTU, the only difference is that Modbus RTU has a two-byte CRC check, while Modbus TCP does not.
The communication format of Modbus ASCII and Modbus RTU is actually to split each byte (for example 27H) of Modbus RTU into two bytes, the upper four bits (2) and the lower four bits (7), and use the ASCII code. Show (32 37), and then add the start character and end character to the frame respectively. Of course, the verification methods of Modbus RTU and Modbus ASCII are different, which are not introduced here, so the same Modbus RTU mode and Modbus ASCII mode are displayed. Out, although there is a big difference in length, the actual meaning is the same.