【正文】 OPC 項(xiàng)對(duì)象包含在 OPC 組對(duì)象中，一個(gè)組對(duì)象可以 包含多個(gè)項(xiàng)對(duì)象，同樣由客戶端定義和維護(hù)。 OPC 數(shù)據(jù)訪問(wèn)規(guī)范 OPC 規(guī)范定義了兩套接口標(biāo)準(zhǔn)，包括自動(dòng)化標(biāo)準(zhǔn) (Automation Interface Standard)和自定義接口標(biāo)準(zhǔn) (Custom Interface Standard)。這樣的工業(yè)標(biāo)準(zhǔn)的提供，乃是 OPC 的目的所在。 COM 是一種軟件組件間相互數(shù)據(jù)交換的有效方法。對(duì)于客戶程序而言，組件程序所處的位置是透明 的，我們不必編寫(xiě)任何處理遠(yuǎn)程調(diào)用的代碼，因此， DCOM 也是 COM 的無(wú)縫擴(kuò)展。并且 COM 對(duì)象的重用是動(dòng)態(tài)的，即被包容或被聚合對(duì)象的版本更新或功能增強(qiáng)后，包容或聚合對(duì)象根本不需要重新編譯或者重新設(shè)置。 Events 數(shù)據(jù)訪問(wèn)標(biāo)準(zhǔn) 報(bào)警和事件標(biāo)準(zhǔn) OPC Batch 批處理標(biāo)準(zhǔn) OPC Data Exchange 服務(wù)器間數(shù)據(jù)交換標(biāo)準(zhǔn) OPC Historical Data Access 歷史數(shù)據(jù)訪問(wèn)標(biāo)準(zhǔn) OPC Security OPC XMLDA 安全性標(biāo)準(zhǔn) XML 數(shù)據(jù)訪問(wèn)標(biāo)準(zhǔn) OPC Commands 命令標(biāo)準(zhǔn) OPC Complex Data 復(fù)雜數(shù)據(jù)訪問(wèn)標(biāo)準(zhǔn) 鞍山科技大學(xué)本科生畢業(yè)設(shè)計(jì)（論文） 第 6 頁(yè) 冷軋清洗線控制系統(tǒng)設(shè)計(jì) —— 用 C++和 OPC 設(shè)計(jì)二級(jí)控制系統(tǒng) 2 OPC技術(shù)的基礎(chǔ) —COM技術(shù) COM技術(shù)簡(jiǎn)介 COM概念 COM（ Component Object Model，組件對(duì)象模型）是由 Microsoft 提出的組件標(biāo)準(zhǔn)，是 OLE、 ActiveX、 DCOM 技術(shù)的基礎(chǔ)，它不僅定義了組件程序之間進(jìn)行交互的標(biāo)準(zhǔn)，并且也提供了組件程序運(yùn)行所需的環(huán)境。 OPC 技術(shù)是 OPC 基金會(huì)組織制定的工業(yè)控制軟件互操作性規(guī)范，也是微軟為了把WINDOWS 應(yīng)用于控制系統(tǒng)和控制界共同推出的一項(xiàng)技術(shù)。該基金會(huì)的會(huì)員單位在世界范圍內(nèi)超過(guò) 220個(gè)，包括了世界上幾乎全部的控制系統(tǒng)、儀器儀表和過(guò)程控制系統(tǒng)的主要供應(yīng)商。 基于 OPC 標(biāo)準(zhǔn)的數(shù)據(jù)訪問(wèn)方式如圖 。 為了有效地完成信息集成，關(guān)鍵是制訂一種集中于數(shù) 據(jù)訪問(wèn)而不是數(shù)據(jù)類型的開(kāi)放的、有效的通信標(biāo)準(zhǔn)。但由于系統(tǒng)各個(gè)計(jì)算機(jī)的通信協(xié)議依賴于某個(gè)廠家，沒(méi)有形成統(tǒng)一的標(biāo)準(zhǔn)，不同廠家之間的軟件與硬件的集成難于實(shí)現(xiàn)。采用可重復(fù)使用的軟件組件以及利用這些軟件組件所具有的柔性構(gòu)成整個(gè)系統(tǒng)，成為發(fā)展的必然趨勢(shì)，因而通信接口不兼容的問(wèn)題急需解決。 關(guān)鍵詞 ： OPC， 組件對(duì)象模型 ， 客戶端 鞍山科技大學(xué)本科生畢業(yè)設(shè)計(jì)（論文） 第 II 頁(yè) 冷軋清洗線控制系統(tǒng)設(shè)計(jì) —— 用 C++和 OPC 設(shè)計(jì)二級(jí)控制系統(tǒng) Cold Rolling Cleaning Line Control System Design ——Design Second Level Control System with C++ and OPC Abstract There is no universal standard between the driver of traditional industry control system and application program. In order to realize the data exchange and the transmission among the puters with different hardware and software, people must develop respective munication program. As the matter stands, there exist many problems including the high development cost, the duplicated work, inconsistent driver program and visit conflict and so on .It is very difficult to meet the open needs of current the industry control system. OPC (OLE for Process Control, used in process control OLE) technique?s appearance provide the solution. OPC makes the different supply merchant of equipment and the application program exchange data mutually and separate the hardware supplier from the software developer, which puts up a bridge between customers and data resource such as equipment and database etc. OPC is an emerging standard in the process control industry, based on Microsoft COM and DCOM technology. It includes the whole standard collection with interface and method used in the process control automation. This paper introduces the background of OPC technology, as well as its main characteristic and the development condition, and analyzes its core COM and DCOM technology. Then it introduces the OPC data access standard and access method with emphasis, the interface and the munication between OPC server object and client object. In the end, it introduces the application of OPC technology in the cold rolling cleaning line， the connection in the cold rolling cleaning line between OPC server and the field device and that between OPC server and the client side. Keywords: OPC, COM, client side 鞍山科技大學(xué)本科生畢業(yè)設(shè)計(jì)（論文） 第 III 頁(yè) 冷軋清洗線控制系統(tǒng)設(shè)計(jì) —— 用 C++和 OPC 設(shè)計(jì)二級(jí)控制系統(tǒng) 目 錄 摘 要 ........................................................................................................................................... I Abstract ...................................................................................................................................... II 1 緒 論 ...................................................................................................................................... 1 研究背景 ...................................................................................................................... 1 OPC 的基礎(chǔ)知識(shí) .......................................................................................................... 1 OPC 產(chǎn)生的背景 ............................................................................................... 1 OPC 的歷史 ....................................................................................................... 4 OPC 的現(xiàn)狀和發(fā)展 ........................................................................................... 5 2 OPC 技術(shù)的基礎(chǔ) —COM技術(shù) .............................................................................................. 6 COM 技術(shù)簡(jiǎn)介 ............................................................................................................. 6 COM 概念 .......................................................................................................... 6 COM 對(duì)象 .......................................................................................................... 7 COM 接口 ——IUnknown 接口 .................................................................................. 7 COM 擴(kuò)展 ——分布式 COM（ DCOM） .................................................................. 8 3 OPC 技術(shù)介紹 ........................................................................................................................ 8 基于 COM 技術(shù)的 OPC ............................................................................................... 8 OPC 數(shù)據(jù)訪問(wèn)規(guī)范 .................................................................................................... 10 OPC 數(shù)據(jù)訪問(wèn)服務(wù)器的對(duì)象 ................................................................................... 10 OPC 數(shù)據(jù)訪問(wèn)方法 .................................................................................................... 12 OPC 服務(wù)器對(duì)象及其組對(duì)象接口 ............................................................................ 14 OPC 服務(wù)器接口 ............................................................................................. 14 OPC 組對(duì)象接口 ...........