What is a Modbus GatewayA Modbus gateway is to convert a Modbus protocol frame into other protocol frames.For example, the data of Modbus RTU and Modbus TCP data can be converted to each other; the application development of master request and slave response can also be carried out to modbus over rs485 improve the efficiency of protocol conversion; The storage gateway replaces the host to initiate active reporting of Modbus requests. The device is in Modbus gateway mode to ensure the Modbus conversion efficiency to discard non-Modbus data and prevent interference to the serial bus.The difference between the three data framesThe Modbus protocol defines a simple protocol data unit (PDU) that is independent of the basic communication layer and consists of function code (1Bit) + data (n Bit);Modbus RTU data frame: encoded in hexadecimal, including address field (1Bit) + PDU + CRC check (2Bit);Modbus TCP data frame: encoded in hexadecimal, including transaction identifier (2Bit) + protocol identifier (00 00: AC-DC single channel 2 bytes, indicating Modbus RTU protocol) + length (2Bit) + address field (1Bit) + PDU;Modbus ASCII data frame: encoded in ASCII, including start character (':') + address code (2 Bit) + data (0 to 2*255 Bit) + LRC check (2Bit) + line feed (CR, LF) )
