The Design And Implementation Of A Data Conversion And Transmission System Based On RS485 And LAN

Industries’ updating speed in field industrial instrument is far behind than its development and changing. To solve this problem, data converting and transmission system based on RS485 and LAN are put up with. This system mainly converts the old instrument common signal output to an unified data form, and transfer to upper computer through the commonly used RS485 and LAN, so as to control all the data.This system is consisted of data-converting and data-transmission and is focused on MSP430F5438 A 16 SCM to design its external circuit. The 6 front data-converting signal types are analog signals as 4~20m A、0~10m A、1~5V、0~10V, and figure signals as RS232、RS485. The SCM MSP430F5438 A collects and receives signals through 12 ADC and serial port, and then packages and stores into FIFO loop buffer in an unified form to be sending. Pick SN75LBC184 as converting chip of truck transmission hardware interface, realize Modbus RTU GSML protocol, then transfer the data to upper computer. The other is based on micro-TCP/IP protocol,namely LAN truck transmission of u IP protocol. Pick integration MAC and 10BASE-T PHY, ENC28J60 with fastest transmission speed to 10Mb/s as Ethernet drive controller, realize u IP protocol to transfer data to upper computer.Through general adjusting,the paper designs a system which can totally realize the converting of Modbus and u IPTCP/IP protocol data form, and transfer data between the RS485 truck or LAN truck and upper computer. It is low-cost, easy-porting and reliabletransmission with practical significance and applying space.