【正文】 SMB89 0D SMB189 信息的結(jié)束字符 0D SMB90 5 SMB190 空閑時(shí)間（按 ms 設(shè)定） 5ms SMB94 14 SMB194 要接收的最大字符數(shù)（ 1~255 字節(jié)） 14 表 22 2． 特殊標(biāo)志位及中斷 接收字符中斷：中斷事件號(hào)為 8（端口 0）和 25（端口 1）。 接收（ RCV）指令：允許輸入端 EN 有效時(shí)，指令初始化通信操作， 通過(guò)指定端口（ PORT）從遠(yuǎn)程設(shè)備上讀取數(shù)據(jù)存儲(chǔ)于數(shù)據(jù)緩沖區(qū)（ TBL）。 IMATIC編程器和計(jì)算機(jī)的默認(rèn)地址是 0，操作面板（如 TD200、 P15） 的默認(rèn)地址是 1，PLC 的默認(rèn)地址是 2，可運(yùn)行 STEP7Micro/WIN32 修改地址。通信幀由特殊的起始和結(jié)束字符、源和目的站地址、幀長(zhǎng)度和數(shù)據(jù)完整性檢查組成。如果網(wǎng)絡(luò)中有第二個(gè)主站，它只能很有限地訪問(wèn)第一個(gè)主站的從站。 PROFIBUS 網(wǎng)絡(luò)通常有一個(gè)主站和幾個(gè) I/O 從站。每個(gè) S7200 和 EM277 模塊保留兩個(gè)連接，其中一個(gè)給 SIMATIC 編程器或計(jì)算機(jī)，另一個(gè)給操作面板。這種連接可以是兩個(gè)設(shè)備之間的非公用連接，連接數(shù)量有一定限制。 五 MPI 協(xié)議 MPI(MultiPoint Interface)協(xié)議適用于多點(diǎn)接口，可以是主 /主協(xié)議或主 /從協(xié)議，協(xié)議操作有賴于設(shè)備類型。 對(duì)于任何一個(gè)從站有多少個(gè)主站和它通信， PPI 并沒(méi)有限制，但在網(wǎng)絡(luò)中最多只能有 32個(gè)主站。 主站可以是其他 CPU 主機(jī)（如 S7300 等）、 SIMATIC 編程器或 TD200 文本顯示器等。主站可以對(duì)網(wǎng)絡(luò)上另一臺(tái)設(shè)備發(fā)出初始化申請(qǐng)，從站只是響應(yīng)來(lái)自主站的申請(qǐng)。 西門子產(chǎn)品所用的通信協(xié)議包括通用協(xié)議和公司專用協(xié)議 。 異步通信的特點(diǎn)：不要求收發(fā)雙方時(shí)鐘的嚴(yán)格一致，實(shí)現(xiàn)容易，設(shè)備開(kāi)銷較小，但每個(gè)字符要附加 2～ 3位用于起止位，各幀之間還有間隔，因此傳輸效率不高。 Abstract With the development of puter work technology and factory automation degree rise ceaselessly, Open and multi function work munication requirements of PLC bee the essential condition. In practical application, the PLC host and extension module to exchange information between PLC host and other host, or other equipment also often exchange information. So through this topic design of munication between PLC and frequency converter means to get a preliminary understanding, this topic mainly to learn S7200 and Mitsubishi Inverter between the most basic means of munication. Access to information through the research protocol, S7200 and Mitsubishi Inverter serial port munication research. Set the task started learning S7200 and Mitsubishi Inverter munication format, by the PLC to start, stop, run the frequency of such instruction, to control the inverter operation and frequency output. In under the guidance of a mentor after several modifications, debugging set program ladder chart. Through this topic design improves their ability to work independently and creativity, strengthen the basic and professional skills, let I to PLC and to deepen the understanding of one pace. PLC as the core part of industrial automatic control, single programming and maintenance of relatively simple, while the industrial work munication requirements of both stability, rapidity, flexibility and patibility with third party equipment, so the industrial munication works bee industrial automation system settings and II the difficulties of implementation. Frequency converter and PLC in free port mode of munication, it has great flexibility, convenient for engineering application. III 目 錄 摘 要 .............................................................................................................................. I Abstract .......................................................................................................................... I 目 錄 .......................................................................................................................... III 第一章 緒論 ..................................................................................................................1 串行通信基本概念及特點(diǎn) ....................................................................................... 1 串行通信的分類 ..................................................................................................... 1 通信協(xié)議 .................................................................................................... 2 通信設(shè)備 .................................................................................................... 3 第二章 PLC 的自由口串行通信 .................................................................................5 自由口指令及應(yīng)用 .................................................................................................. 5 自由口指令 ..............................................