ModBUS 協(xié)議具有偵錯(cuò)能力強(qiáng)、數(shù)據(jù)傳輸量大、實(shí)時(shí)性好等特點(diǎn)，因而成為目前自控
領(lǐng)域使用非常廣泛的通訊語言。本文通過一個(gè)應(yīng)用實(shí)例介紹如何利用微機(jī)編程實(shí)現(xiàn)在線通訊ModBUS 消息環(huán)的工作過程，在可視化語言環(huán)境下完成地址域、功能代碼域、數(shù)據(jù)域的分配及CRC 校驗(yàn)，從而實(shí)現(xiàn)計(jì)算機(jī)與遠(yuǎn)程控制單元數(shù)據(jù)傳輸。
關(guān)鍵詞：ModBUS 協(xié)議、查詢、回應(yīng)、RTU 模式、CRC 校驗(yàn)。
Abstract: ModBUS protocol have powerful data transmittability , detectability and
realtime processing capability, so it had become a communication language that applicate widely in autocontrol field at present. This paper introduced a instance , how it realized a process about ModBUS structure of message loop and communication online, besides it created a frame which included address field ,option code field ,data field and CRC checking in visual programming environment, and send the
frame to Remote Termimal Unit.
Keyword: ModBUS protocol、query、reply、RTU mode、CRC check.