【正文】 hines. The article includes an overall designing plan. In the port of the PC, using a S2485,dedicated RS232/485 converter chip , converts the RS232 level into the RS485 level. In the port of 80C51 singlechip, MAX485 will be used to convert TTL level into RS485 level. In this way ,munications can be achieved between PC and lower machine, as well as lower machines. In the basis of hardware design, the municational protocol is carried order to achieve the accuracy of the data transmission, the error checking and correction is implemented,as well as the study of reliability . After software programming and program debugging, the system can achieve data transmission between PC machine and singlechip,as well as singlechips. Keywords： PC Machine。 RS485。 Multimachine Communication 武漢工程大學(xué)畢業(yè)設(shè)計(jì)（論文）說明書 目 錄 摘 要 .........................................................................................................................................................................I ABSTRACT............................................................................................................................................................... II 第一章 緒論 ................................................................................................................................................................1 引言 .............................................................................................................................................................................1 研究的背景及意義 ...............................................................................................................................................1 論文的主要內(nèi)容 ....................................................................................................................................................2 第二章 多機(jī)通信基礎(chǔ) .........................................................................................................................................3 數(shù)據(jù)通信基礎(chǔ) .........................................................................................................................................................3 異步串行通 信接口標(biāo)準(zhǔn) .....................................................................................................................................5 通信芯片的介紹 ....................................................................................................................................................9 第三章 系統(tǒng)方案設(shè)計(jì) ...................................................................................................................................... 12 系統(tǒng)總體設(shè)計(jì) ...................................................................................................................................................... 12 系統(tǒng)主要構(gòu)成部分 ............................................................................................................................................ 12 系統(tǒng)主從通信的基本條件 ............................................................................................................................. 14 第四章 系統(tǒng)軟件設(shè)計(jì)與調(diào)試 .................................................................................................................... 15 PC 機(jī)與多個(gè) 80C51 通信原理 ...................................................................................................................... 15 通信狀態(tài)的設(shè)置 ................................................................................................................................................. 15 PC 機(jī)與多個(gè) 80C51 通信的控制 ................................................................................................................. 17 通信協(xié)議 ................................................................................................................................................................ 18 多機(jī)發(fā)送時(shí)的分時(shí)說、聽 ............................................................................................................................. 20 差錯(cuò)控制 ................................................................................................................................................................ 22 系統(tǒng)程序設(shè)計(jì) ...................................................................................................................................................... 22 程序調(diào)試 ................................................................................................................................................................ 29 第五章 系統(tǒng)可靠性分析 ................................................................................................................................ 33 串行通信 可靠性評(píng)測(cè)指標(biāo) ............................................................................................................................. 33 程序跳飛而造成總線沖突 ............................................................................................................................. 33 失效保護(hù) ................................................................................................................................................................ 34 通信協(xié)議提高通信可靠性 ............................................................................................................................. 35 程序抗干擾措施 ................................................................................................................................................. 37 第六章 總結(jié) ............................................................................................................................................................. 39 致謝 ................................................................................................................................................................................. 40 參考文獻(xiàn) ...................................................................................................................................................................... 41 附錄 1