外文資料翻譯---工業(yè)控制系統(tǒng)與協(xié)同控制系統(tǒng)

1、<p><b>　　外文資料翻譯</b></p><p>　　工業(yè)控制系統(tǒng)與協(xié)同控制系統(tǒng)</p><p>　　當今的控制系統(tǒng)被廣泛運用于許多領(lǐng)域。從單純的工業(yè)控制系統(tǒng)到協(xié)同控制系統(tǒng)（CCS），控制系統(tǒng)不停變化，不斷升級，現(xiàn)在則趨向于家庭控制系統(tǒng)，而它則是這兩者的變種。被應(yīng)用的控制系統(tǒng)的種類取決于技術(shù)要求。而且，實踐表明，經(jīng)濟和社會因素也對此很重要。任何決定都

2、有它的優(yōu)缺點。工業(yè)控制要求可靠性，完整的文獻記載和技術(shù)支持。經(jīng)濟因素使決定趨向于協(xié)同工具。能夠親自接觸源碼并可以更快速地解決問題是家庭控制系統(tǒng)的要求。多年的操作經(jīng)驗表明哪個解決方法是最主要的不重要，重要的是哪個可行。由于異類系統(tǒng)的存在，針對不同協(xié)議的支持也是至關(guān)重要的。本文介紹工業(yè)控制系統(tǒng)，PlC controlled turn key系統(tǒng)，和CCS工具，以及它們之間的操作。</p><p><b>　

3、　引言：</b></p><p>　　80年代早期，隨著為HERA(Hadron-Elektron-Ring-Anlage)加速器安裝低溫控制系統(tǒng)，德國電子同步加速器研究所普遍開始研究過程控制。這項新技術(shù)是必需的，因為但是現(xiàn)有的硬件沒有能力來處理標準過程控制信號，如4至20毫安的電流輸入和輸出信號。而且軟件無法在0.1秒的穩(wěn)定重復(fù)率下運行PID控制回路。此外，在實現(xiàn)對復(fù)雜的低溫冷藏系統(tǒng)的開閉過程中，頻

4、率項目顯得尤為重要。</p><p>　　有必要增加接口解決總線問題并增加運算能力，以便于低溫控制。因為已安裝的D / 3系統(tǒng)[1] 只提供了與多總線板串行連接，以實現(xiàn)DMA與VME的連接并用其模擬多總線板的功能。溫度轉(zhuǎn)換器的計算功能來自一個摩托羅拉MVME 167 CPU和總線適配器，以及一個MVME 162 CPU。其操作系統(tǒng)是VxWorks，而應(yīng)用程序是EPICS。</p><p>

5、　　由于對它的應(yīng)用相當成功，其還被運用于正在尋找一個通用的解決方案以監(jiān)督他們的分布式PLC的公共事業(yè)管理。</p><p>　　德國電子同步加速器研究所對過程管理系統(tǒng)的篩選</p><p>　　集散控制系統(tǒng)（D/ 3）：</p><p>　　市場調(diào)查表明：來自GSE的D / 3系統(tǒng)被HERA低溫冷藏工廠選中。因為集散控制系統(tǒng)（D/ 3）的特性，所以這決定很不錯。在展

6、示端和I / O端擴展此系統(tǒng)的可能將有助于解決日益增加的 HERA試驗控制的要求。制約系統(tǒng)的大小的因素不是I / O的總數(shù)，通信網(wǎng)絡(luò)的暢通與否。而通信網(wǎng)絡(luò)的暢通與否取決于不存檔的數(shù)據(jù)總量，不取決于報警系統(tǒng)中配置的數(shù)據(jù)。</p><p>　　擁有DCS特點（Cube）的SCADA系統(tǒng)：</p><p>　　相對于Y2K問題促使我們尋找一個升級版或者代替版來代替現(xiàn)有的系統(tǒng)而言，以上提到的D

7、/ 3系統(tǒng)有一些硬編碼的限制。由于急需給Orsi公司提供他們的產(chǎn)品，Cube開始起作用了[2]。該項目包括安裝功能的完全更換。這包括D / 3，以及德國電子同步加速器研究所的集成總線SEDAC和VME的溫度轉(zhuǎn)換器。該項目很有前景。但是因為HERA試驗原定時間是有限制的，所以技術(shù)問題和組織問題也迫使計劃提前。在供應(yīng)商網(wǎng)站上的最后驗收測試又出現(xiàn)了戲劇性的性能問題。有兩個因素引起了這些問題。第一個跟低估在1赫茲運行的6級溫度轉(zhuǎn)換器的CPU負荷

8、有關(guān)。第二個由現(xiàn)有D / 3系統(tǒng)復(fù)雜的功能造成的額外負荷引起的。每個數(shù)字和模擬輸入和輸出通道在D / 3系統(tǒng)里的自身報警限值也被低估了。所有的附加功能都必須添加進去。最后，所有網(wǎng)絡(luò)負載的報警限值，尤其是SCADA系統(tǒng)，也促使網(wǎng)絡(luò)生成了限制。</p><p>　　最后，與Orsi公司的合同被取消了。升級的D / 3系統(tǒng)是唯一可能的解決辦法。在2003年3月，此系統(tǒng)最后被付諸實踐。</p><p&

9、gt;　　現(xiàn)在，相比“純粹”SCADA系統(tǒng)的異質(zhì)環(huán)境，Cube有同質(zhì)配置環(huán)境的優(yōu)勢。</p><p>　　SCADA（PVSS -Ⅱ）：</p><p>　　在HERA加速器上的H1實驗中，實驗人員為升級他們的低速控制系統(tǒng)，決定使用PVSS -Ⅱ?，F(xiàn)有的系統(tǒng)是由H1合作組的幾名成員開發(fā)的，而現(xiàn)在卻難以維持了。在CERN由聯(lián)合控制項目[4]進行的廣泛調(diào)查促使他們做出使用PVSS作為代替品的決

10、定。PVSS是一個“純粹”的監(jiān)控和數(shù)據(jù)采集系統(tǒng)（SCADA系統(tǒng)）。其核心元素叫做事件管理器。它收集的數(shù)據(jù)主要是由I/ O設(shè)備提供。它還提供附加的管理服務(wù)，如：控制經(jīng)理，數(shù)據(jù)庫管理，用戶界面，API經(jīng)理以及在建的HTTP服務(wù)器。該PVSS腳本庫允許執(zhí)行復(fù)雜的序列以及復(fù)雜的圖形。相比其他SCADA系統(tǒng)PVSS帶有一個基本特點：它提供了API給設(shè)備的數(shù)據(jù)。</p><p>　　SCADA系統(tǒng)的一個主要缺點是其中的兩個數(shù)

11、據(jù)庫，一個為PLC’s服務(wù)，另一個為SCADA系統(tǒng)服務(wù)，這兩個數(shù)據(jù)庫必須維持。集成環(huán)境將努力克服這個限制。</p><p><b>　　EPICS：</b></p><p>　　在德國電子同步加速器研究所，EPICS從問題解決系統(tǒng)演化成了全集成控制系統(tǒng)。從成為低溫控制系統(tǒng)的數(shù)據(jù)收集器和數(shù)量控制器，EPICS成為了德國電子同步加速器研究所公用事業(yè)集團使用的核心系統(tǒng)。此外

12、，通過 Industry Pack（IP）模塊的手段，它還能運用于通過VME板卡的任何數(shù)據(jù)。EPICS通過其完整的功能，運用于沒有由D / 3系統(tǒng)控制的低溫冷藏系統(tǒng)。所有大約50個輸入輸出控制器運作大約25000業(yè)務(wù)處理記錄。</p><p>　　作為一個SCADA系統(tǒng)的EPICS：</p><p>　　該公共事業(yè)組（水，電，壓縮空氣，加熱和調(diào)溫）使用各種散布在整個德國電子同步加速器研究所

13、網(wǎng)站上的PLC。IOC向客戶提供接口并采集數(shù)據(jù)。此外，如通道歸檔和圖形顯示（dm2k） 會被使用。默認名決議和目錄服務(wù)器（域名服務(wù)器）用于連接 在TCP客戶端和服務(wù)器應(yīng)用程序。所有這些都是基本的SCADA功能。所有的配置文件（圖形工具，報警處理程序和歸檔）提供了一種靈活的配置方案。德國電子同步加速器研究所公用事業(yè)集團已制定了一套工具來創(chuàng)建IOC數(shù)據(jù)庫和配置文件。這樣，控制組提供的服務(wù)保持EPICS工具，而用戶可以精力集中在被控制的設(shè)備上

14、了。</p><p>　　作為一個DCS系統(tǒng)的EPICS：</p><p>　　作為SCADA系統(tǒng)的基本組成部分，EPICS還提供完整的輸入輸出控制器（IOC）。IOC提供所有功能DCS系統(tǒng)要求，如：實施每個記錄的標準的屬性；執(zhí)行每個記錄時的報警檢查過程；控制記錄，如PID。靈活的命名方案，默認的顯示和每個記錄的報警屬性緩和了運作工具和IOC之間的連接。靈活的數(shù)據(jù)采集模式，支持調(diào)查模式以及

15、發(fā)布訂閱模式。后者大大降低了信息擁堵的情況。</p><p><b>　　PLC’s：</b></p><p>　　PLC’s同樣提供豐富的功能，因為以前它是獨一無二的控制系統(tǒng)。此外，定期執(zhí)行一個確定功能的基本特征也讓他們通過以太網(wǎng)通信，包括內(nèi)置的HTTP服務(wù)器和不同集合的通訊方案。除了通信處理器，顯示器能和PLC’s連接。</p><p>&

16、lt;b>　　智能I / O：</b></p><p>　　I / O設(shè)備上的新發(fā)展允許在更小的群體中集群I / O并把這些集群I / O渠道鏈接到控制系統(tǒng)。PLC’s對于分布式I / O已不再重要。PLC’s和智能I / O子系統(tǒng)的差別正在消失。</p><p><b>　　功能</b></p><p>　　持續(xù)不斷的問題，

17、如為什么控制系統(tǒng)的加速器和其他高度專業(yè)化的設(shè)備聯(lián)合協(xié)同發(fā)展。但是，在極少數(shù)情況下，只通過商業(yè)的立場時難以回答的。在這里，我們試圖總結(jié)不同控制方法的基本功能。</p><p><b>　　前端控制器： </b></p><p>　　對控制系統(tǒng)的核心要素之一，是前端控制器。PLC’s可用于實施控制功能的設(shè)備。它的缺點就是復(fù)雜，難以達到控制屬性。例如確定通信協(xié)議和最后在顯示

18、、報警和歸檔方案，一個控件的所有屬性像P，I和D參數(shù)，還有報警限制及其他附加的屬性必須得到解決。另外，這些嵌入式屬性修改是很難尋覓，因為其中涉及兩個或兩個以上軌道系統(tǒng)這可能是一個有力的論據(jù)是，為什么控制回路主要實施在IOC層面，而不是PLC’s層面。</p><p>　　I / O和控制回路</p><p>　　復(fù)雜的控制算法和控制回路和域名DCS控制系統(tǒng)一樣。對顯示和控件的屬性的支持是必

19、不可少的。</p><p><b>　　頻率/國家計劃</b></p><p>　　在控制系統(tǒng)中，頻率程序可以運行任何處理器。運行時環(huán)境取決于相關(guān)代碼?？刂葡到y(tǒng)程序直接履行運行前端處理器的監(jiān)控。為復(fù)雜的啟動和關(guān)閉處理程序設(shè)立的頻率程序也可以運行工作站。國家機器的基本功能在IEC 61131中得到了落實。編碼發(fā)電機可以產(chǎn)生C代碼。</p><p>

20、;<b>　　硬件支持</b></p><p>　　對現(xiàn)場總線和起源于I / O的Ethernet的支持是為SCADA系統(tǒng)服務(wù)的一個基本功能。所有SCADA系統(tǒng)在市場商業(yè)運作中是可行的。配置特定驅(qū)動器和數(shù)據(jù)轉(zhuǎn)換器的集成硬件在商業(yè)環(huán)境中是一個難點。開放API或腳本支持有時有助于整合用戶的硬件。如果不向控制系統(tǒng)提供這些工具，就很難整合客戶硬件。</p><p>　　新的工

21、業(yè)標準，如OPC，和OPC設(shè)施聯(lián)系，還和控制系統(tǒng)之間互相聯(lián)系。這種功能的基本條件是強調(diào)操作系統(tǒng)。在這種情況下，OPC更趨向于微軟的DCOM標準?；诳刂葡到y(tǒng)的UNIX很難互相連接。只有支持多平臺的控制系統(tǒng)可以在異構(gòu)環(huán)境中發(fā)揮主要作用。</p><p>　　由于為客戶或?qū)I(yè)硬件的支持有限，所以新的控制系統(tǒng)有理由得到發(fā)展。</p><p><b>　　顯示和操作</b>&

22、lt;/p><p>　　除了前后系統(tǒng)，操作接口在控制系統(tǒng)的兼容過程中有重要的作用。因為個人呢工具由不同的團隊開發(fā)，所以協(xié)作實現(xiàn)的工具包可能變動。</p><p><b>　　1圖形</b></p><p>　　天氣顯示是任何控制系統(tǒng)的廣告招牌。商業(yè)天氣顯示也有著豐富的功能和許多特色。開始使用所有這些特征，所有這些功能的使用人會發(fā)現(xiàn)，所有個別屬性的圖

23、形對象要分別指定。一個輸入通道不只由物業(yè)的價值決定的，而且更由包括像展出范圍和報警值決定的。一再分辨所有性能可能是個非常乏味的工作。有些系統(tǒng)產(chǎn)生圖形原型對象。這些原型圖形或模板很復(fù)雜，但需要一個專家來生產(chǎn)。</p><p>　　DCS或自定義天氣顯示程序使用常見的I / O點屬性集。這個預(yù)定義的命名方案填寫標準的屬性值，因此只需要進入記錄，或設(shè)備名稱進入配置工具。</p><p><

24、b>　　2 報警系統(tǒng)</b></p><p>　　警報可以很好的區(qū)分不同的控制系統(tǒng)架構(gòu)。實現(xiàn)I / O對象的這些系統(tǒng)在前后端電腦提供警報檢查。只能讀懂I / O點的系統(tǒng)在I / O處理過程中添加了警報檢查。I / O對象途徑在前后端系統(tǒng)的本土項目語言安插了警報檢測。，I / O點導(dǎo)向系統(tǒng)通常要在他們的腳文本語言中實現(xiàn)這種功能。這是通常效率較低且容易出錯，因為所有屬性必須被單獨配置，這導(dǎo)致了一系列

25、特性。不僅為每個I / O點的錯誤狀態(tài)結(jié)束是個人的I / O點，但報警限值和每個報警的輕重，應(yīng)當限制定義為I / O點，如果它希望能夠改變運行值。</p><p>　　這種影響在SCADA和DCS系統(tǒng)之間也形成了影響。SCADA系統(tǒng)本就讀不懂報警系統(tǒng)。DCS系統(tǒng)的優(yōu)勢在于管理人員既可以登記警報狀態(tài)，從而提前得到信息，控制蔓延到在控制系統(tǒng)周圍的變化。后一種情況是唯一可能的系統(tǒng)。</p><p&g

26、t;<b>　　3 趨勢和歸檔</b></p><p>　　趨勢已成為控制系統(tǒng)架構(gòu)中的一個重要的業(yè)務(wù)。趨勢是必要的跟蹤誤差條件。實現(xiàn)的數(shù)據(jù)存儲有能力儲存完整控制目標，大部分的趨勢工具標量數(shù)據(jù)存檔。附加特性如條件趨向或相關(guān)情節(jié)在個人實施起了影響。</p><p><b>　　4編程接口</b></p><p>　　關(guān)于開放編

27、程接口，PLC’s和DCS系統(tǒng)有相同策略。他們運行可靠，因為他們沒有辦法整合 可定制的合作去干涉內(nèi)部處理。因此，客戶定制精品，這個極其昂貴的。</p><p>　　由于SCADA系統(tǒng)必須能夠 與多種I / O子系統(tǒng)連接已經(jīng)在API上建立了I / O子系統(tǒng)以整合 自定義功能。</p><p>　　協(xié)作系統(tǒng)尤其需要一定的開放性以實現(xiàn)各種發(fā)展組織的要求。所有級別的編程接口，例如前后端I / O，

28、前后端處理過程和網(wǎng)絡(luò)等，是強制性的。</p><p><b>　　5冗余</b></p><p>　　如果冗余是指管理所有國家，I / O所有值無縫道岔當前正在運行，它是一個域，只有少數(shù)集散系統(tǒng)。自定義或CCS實施不提供這種功能。也許是因為巨大努力和事實，它是只需要在罕見的事例。此外，處理器冗余，或多余的網(wǎng)絡(luò)，或I / O子系統(tǒng)是為一定的商業(yè)集散控制系統(tǒng)指定的。<

29、;/p><p>　　先進的安全要求是由多余的PLC子系統(tǒng)覆蓋。這些安裝在（核）電廠。個人保護系統(tǒng)（PPS）的要求有時候會由冗余的PLC’s來滿足。在過程控制中，冗余的PLC’s只在少數(shù)情況下使用。</p><p><b>　　6命名空間</b></p><p>　　在供應(yīng)鏈系統(tǒng)中，SCADA系統(tǒng)的單位名稱空間形容成警報部分。有些SCADA系統(tǒng)（如P

30、VSS – II）提供在少數(shù)情況下的控制對象或結(jié)構(gòu)化數(shù)據(jù)。這些對象由一系列特性（包括I / O點）和一套方法（宏或函數(shù)）組成。這些途徑的其一是UniNified工業(yè)控制系統(tǒng)（UNICOS）在歐洲核子研究中心[5]。</p><p>　　DCS系統(tǒng)和大多數(shù)習(xí)慣性/協(xié)作系統(tǒng)是有記錄的，或是設(shè)備為主。不同之處是，通常一個記錄被連接到一個單一I / O點，提供這樣的執(zhí)行記錄，如個人工程單元，顯示和警報限值。設(shè)備為本的方法

31、允許連接幾個I / O點。而（EPICS的）記錄只服務(wù)于一組特定的內(nèi)置功能。</p><p>　　命名等級不特定于實施類型。它們可用于一些系統(tǒng)。分層命名方案是肯定可取的。</p><p><b>　　實施策略</b></p><p>　　表現(xiàn)完各種可能的控制方法后，該是查看控制系統(tǒng)的完成情況了。</p><p>　　從I

32、 / O級開始，他們必須決定是否需要商業(yè)解決。特殊的I / O不總是需要定制解決方案。信號可以被轉(zhuǎn)換成標準的信號，但是這并不適用于所有的信號。信號水平可能需要定制的發(fā)展，這必須納入整體控制架構(gòu)。信號不能被連接到標準I / O接口，也許有可能發(fā)展的I / O控制器的 允許實施現(xiàn)場總線接口，這能夠整合商業(yè)控制系統(tǒng)。整合水平是不可能定制前端控制器，如VME，開始發(fā)揮作用了。</p><p>　　Turn Key 系統(tǒng)

33、：</p><p>　　在工業(yè)中，有個明顯的趨勢就是產(chǎn)生了Turn Key 系統(tǒng)。它允許對整個系統(tǒng)進行模塊化設(shè)計。個別元件分包給幾個公司進行本地測試。一旦交付施工現(xiàn)場，驗收測試就已經(jīng)過去了，第二個階段，整合融入全球控制系統(tǒng)的子系統(tǒng)開始。雖然控制回路的詳細規(guī)格等，是現(xiàn)在子系統(tǒng)合同的一部分。客戶必須明確多少信息子系統(tǒng)可以被使用。</p><p>　　大多數(shù)Turn Key系統(tǒng)與PLC一起交付使

34、用。瑞士光源（SLS）的建立過程已顯示，這也是基于I/ O系統(tǒng)運行的VME運行 CCS的，這樣才可以成功啟用[6]。</p><p><b>　　基于系統(tǒng)的PLC：</b></p><p>　　基于系統(tǒng)的PLC是Turn Key系統(tǒng)成果。下一個明顯的方法看起來可能是除了商業(yè)PLC，就是商業(yè)SCADA系統(tǒng)。優(yōu)勢就是明顯和PLC一樣：沒有穩(wěn)定的軟編程器，僅有配置，支持和良

35、好的文件系統(tǒng)。在德國電子同步加速器研究所，我們成功地建立了控制組和公共事業(yè)組之間的關(guān)系。盡管是EPICS編碼，但其最大的優(yōu)勢就是能調(diào)整雙方的特殊要求。</p><p><b>　　工業(yè)解決方案：</b></p><p>　　一旦工業(yè)開始支持協(xié)作控制系統(tǒng)，CCS的解決方案和商業(yè)之間的差異將漸漸變小。在KEK，公司簽訂合同為KEK-B升級提供程序員。這些程序員進行了書面驅(qū)

36、動程序和應(yīng)用程序代碼的EPICS培訓(xùn)。因此，KEK-B控制系統(tǒng)是工業(yè)用和民用升級軟件的混合體。這是CCS實施中工業(yè)參與的另一個例子。</p><p><b>　　成本：</b></p><p>　　自從個人電腦出現(xiàn)后，“一臺個人電腦的總成本是多少？”這樣的問題一直使人忙碌。所有的答案不盡相同的極端?，F(xiàn)在的問題什么是一個控制系統(tǒng)的TCO可能作出類似的結(jié)果。如果你進入商業(yè)

37、領(lǐng)域，你要支付的初始證照費用，而通常這是由供應(yīng)商或分包商支付的，你付錢進行的軟件支持，可能或可能不會包括你更新證照的費用。</p><p>　　如果你去尋求合作方式，你可能與公司簽合同或完成一切。而“時間與金錢說”在工業(yè)中同樣成立。你親自完成可能更自由靈活，但是有點難度。你 可以依靠合作，以提供新的功能和版本，或者你可以為自己作出貢獻。主要的區(qū)別就是要為控制系統(tǒng)計入長期成本。</p><p&g

38、t;　　德國電子同步加速器研究所粗略估計，控制應(yīng)用程序，如支持商業(yè)模式的D / 3，和支持協(xié)作模式的EPICS幾乎是相同的。在該軟件支持和升級證照的費用，相當于1.5倍的FTE’s 。FTE’s是關(guān)于人力資源的內(nèi)容，對于支持新的硬件和升級EPICS是必要的。</p><p><b>　　結(jié)論</b></p><p>　　根據(jù)控制項目不同的規(guī)模和要求，整合的商業(yè)解決方案

39、和基于協(xié)作應(yīng)用程序的解決方案在百分之零到一百都有可能。。這適用于長遠的技術(shù)支持。在安全問題上的特殊需要或人力資源的缺乏可能會擴大商機。接口專業(yè)硬件，掌控在手的談判或商業(yè)解決方案的初始成本有可能促使大規(guī)模的合作。只要如EPICS的協(xié)作途徑，保持最新并運行如商業(yè)方案一樣穩(wěn)定和強勁，它們就能在互補共生的控制世界中占有一席之地。</p><h2>　　INDUSTRIAL AND COLLABORATIVE CONTRO

40、L SYSTEMS </h2><p>　　A COMPLEMENTARY SYMBIOSIS –</p><p>　　Looking at today’s control system one can find a wide variety of implementations. From pure industrial to collaborative control system (

41、CCS) tool kits to home grown systems and any variation in-between. Decisions on the type of implementation should be driven by technical arguments Reality shows that financial and sociological reasons form the complete p

42、icture. Any decision has it’s advantages and it’s drawbacks. Reliability, good documentation and support are arguments for industrial controls. </p><p>　　INTRODUCTION</p><p>　　Process controls i

43、n general started at DESY in the early 80th with the installation of the cryogenic control system for the accelerator HERA (Hadron-Elektron-Ring-Anlage). A new technology was necessary because the existing hardware was n

44、ot capable to handle standard process controls signals like 4 to 20mA input and output signals and the software was not designed to run PID control loops at a stable repetition rate of 0.1 seconds. In addition sequence p

45、rograms were necessary to implement startu</p><p>　　Soon it was necessary to add interfaces to field buses and to add computing power to cryogenic controls. Since the installed D/3 system[1] only provided an

46、 documented serial connection on a multibus board, the decision was made to implement a DMA connection to VME and to emulate the multibus board’s functionality. The necessary computing power for temperature conversions c

47、ame from a Motorola MVME 167 CPU and the field bus adapter to the in house SEDAC field bus was running on an additional MVME </p><p>　　Since this implementation was successful it was also implemented for the

48、 utility controls which were looking for a generic solution to supervise their distributed PLC’s.</p><p>　　A SELECTION OF PROCESS CONTROL SYSTEMS AT DESY</p><h4>　　DCS (D/3) </h2><p&g

49、t;　　As a result of a market survey the D/3 system from GSE was selected for the HERA cryogenic plant. The decision was fortunate because of the DCS character of the D/3. The possibility to expand the system on the displa

50、y- and on the I/O side helped to solve the increasing control demands for HERA. The limiting factor for the size of the system is not the total number of I/O but the traffic on the communication network. This traffic is

51、determined by the total amount of archived data not by the data </p><h4>　　SCADA Systems with DCS Features (Cube) </h2><p>　　The fact that the D/3 system mentioned above had some hard coded limi

52、tations with respect to the Y2K problem was forcing us to look for an upgrade or a replacement of the existing system. As a result of a call for tender the company Orsi with their product Cube came into play [2]. The pro

53、ject included a complete replacement of the installed functionality. This included the D/3 as well as the integration of the DESY field bus SEDAC and the temperature conversion in VME. The project started promis</p>

54、;<p>　　Finally the contract with Orsi was cancelled and an upgrade of the D/3 system was the only possible solution. It was finally carried out in march 2003.</p><p>　　In any case it should be mention

55、ed that the Cube approach had the advantage of a homogeneous configuration environment (for the Cube front end controllers) – compared with heterogeneous environments for ‘pure’ SCADA systems.</p><p>　　SCADA

56、 (PVSS-II)</p><p>　　The H1 experiment at the HERA accelerator decided to use PVSS-II for an upgrade of their slow control systems[3]. The existing systems were developed by several members of the H1 collabor

57、ation and were difficult to maintain. The decision to use PVSS as a replacement was driven by the results of an extensive survey carried out at CERN by the Joint Controls Project [4]. PVSS is a ‘pure’ Supervisory And Dat

58、a Acquisition System (SCADA). It provides a set of drivers for several field buses and generi</p><p>　　One major disadvantage of SCADA systems is the fact that two databases, the one for the PLC and the one

59、for the SCADA system must be maintained. Integrated environments try to overcome this restriction. </p><p><b>　　EPICS </b></p><p>　　EPICS has emerged at DESY from a problem solver to

60、 a fully integrated control system. Starting from the data collector and number cruncher for the cryogenic control system, EPICS made it’s way to become the core application for the DESY utility group. In addition it is

61、used wherever data is available through VME boards or by means of Industry Pack (IP) modules. For those cryogenic systems which are not controlled by the D/3 system EPICS is used with it’s complete functionality. In tota

62、l about 50</p><h4>　　1 EPICS as a SCADA System </h2><p>　　The utility group ( water, electrical power, compressed air, heating and air conditioning) is using a variety of PLC’s spread out over t

63、he whole DESY site. EPICS is used to collect the data from these PLC’s over Profibus (FMS and DP) and over Ethernet (Siemens H1 and TCP). The IOC’s provide the interfaces to the buses and collect the data. The built in a

64、larm checking of the EPICS records is used to store and forward alarm states to the alarm handler (alh) of the EPICS toolkit. In addition tools </p><p>　　client and server applications over TCP. All of these

65、 are basically SCADA functions. </p><p>　　The textual representation of all configuration files ( for the IOC, the graphic tool, the alarm handler and the archiver) provides a flexible configuration scheme.

66、At DESY the utility group has developed a set of tools to create IOC databases and alarm configuration files from Oracle. This way the controls group provides the service to maintain the EPICS tools and the IOC’s while t

67、he users can concentrate on the equipment being controlled. </p><h4>　　2 EPICS as a DCS System </h2><p>　　Besides the basic components of a SCADA system EPICS also provides a full flavoured Inpu

68、t Output Controller (IOC). The IOC provides all of the function a DCS system requires, such as: a standard set of properties implemented in each record, built in alarm checking processed during the execution of each reco

69、rd; control records like PID etc.; configuration tools for the processing engine. The flexible naming scheme and the default display and alarm properties for each record ease the connection be</p><p><b&g

70、t;　　PLC’s </b></p><p>　　PLC’s provide nowadays the same rich functionality as it was known from stand alone control systems in the past. Besides the basic features like the periodic execution of a defi

71、ned set of functions they also allow extensive communication over Ethernet including embedded http servers and different sets of communication programs. Besides the communication processors, display processors can be lin

72、ked to PLC’s to provide local displays which can be comprised as touch panels for operator intervention</p><p>　　These kind of PLC’s are attractive for turn key systems which are commissioned at the vendors

73、site and later integrated into the customers control system. </p><h4>　　Intelligent I/O </h2><p>　　New developments in I/O devices allow to ‘cluster’ I/O in even smaller groups and connect these

74、s clustered I/O channels directly to the control system. PLC’s are not any more necessary for distributed I/O. Simple communication processors for any kind of field buses or for Ethernet allow an easy integration into th

75、e existing controls infrastructure. Little local engines can run IEC 61131 programs. The differences between PLC’s and intelligent I/O subsystems fade away. </p><h3>　　FUNCTIONALITY </h2><p>　　T

76、he ever lasting question why control systems for accelerators and other highly specialized equipment are often home grown or at least developed in a collaboration but only in rare cases commercial shall not be answered h

77、ere. We try to summarize here basic functionalities of different controls approaches.</p><h4>　　Front-end Controller </h2><p>　　One of the core elements of a control system is the front-end cont

78、roller. PLC’s can be used to implement most of the functions to control the equipment. The disadvantage is the complicated access to the controls properties. For instance all of the properties of a control loop like the

79、P, I and D parameter, but also the alarm limits and other additional properties must be addressed individually in order to identify them in the communication protocol and last not least in the display-, alarm- and </p

80、><h4>　　1 I/O and Control Loops </h2><p>　　Complex control algorithms and control loops are the domain of DCS alike control systems. The support for sets of predefined display and controls properti

81、es is essential. If not already available (like in DCS systems) such sets of generic properties are typically specified throughout a complete control system (see namespaces). </p><h4>　　2 Sequence/ State pro

82、grams </h2><p>　　Sequence programs can run on any processor in a control system. The runtime environment depends on the relevance of the code for the control system. Programs fulfilling watchdog functions ha

83、ve to run on the front-end processor directly. Sequence programs for complicated startup and shutdown procedures could be run on a workstation as well. The basic functionality of a state machine can be even implemented i

84、n IEC 61131. Code generators can produce ‘C’ code which can be compiled for the runtime en</p><h4>　　3 Supported Hardware </h2><p>　　The support for field buses and Ethernet based I/O is a basic

85、 functionality for SCADA type systems it is commercially available from any SCADA system on the market. The integration of specific hardware with specific drivers and data conversion is the hard part in a commercial envi

86、ronment. Open API’s or scripting support sometimes help to integrate custom hardware. If these tools are not provided for the control system it is difficult – if not impossible - to integrate custom hardware. </p>

87、<p>　　New industrial standards like OPC allow the communication with OPC aware devices and the communication between control systems. One boundary condition for this kind of functionality is the underlying operatin

88、g system. In the case of OPC it is bound to DCOM which is a Microsoft standard. UNIX based control systems have a hard time to get connected. Only control systems supporting multiple platforms can play a major role in a

89、heterogeneous environments. </p><p>　　As a result the limited support for custom- or specialized hardware may give reason for the development of a new control system.</p><h4>　　Display and Opera

90、tion </h2><p>　　Besides the front-end system the operator interfaces play a major role for the acceptance of a control system. SCADA tools come with a homogeneous look and feel throughout their set of tools.

91、 Toolkits implemented in a collaboration might vary because the individual tools were developed by different teams. </p><h4>　　1 Graphic </h2><p>　　Synoptic displays are the advertising sign for

92、 any control system. Commercial synoptic displays come with a rich functionality and lots of special features. Starting to make use of all these features one will find out that all individual properties of the graphic ob

93、jects must be specified individually. Since SCADA systems must be generic they cannot foresee that an input channel does not only consist of a value but also consists of properties like display ranges and alarm values. D

94、efining all of</p><p>　　DCS or custom synoptic display programs can make use of the common set of properties each I/O point provides. This predefined naming scheme will fill in all standard property values a

95、nd thus only require to enter the record – or device name into the configuration tool. A clear advantage for control systems with a notion of I/O objects rather than I/O points.</p><h4>　　2 Alarming </h2&

96、gt;<p>　　Alarms are good candidates to distinguish between different control system architectures. Those systems which have I/O object implemented also provide alarm checking on the front-end computer. Those syste

97、ms which only know about I/O points have to add alarm checking into the I/O processing. While the I/O object approach allows to implement alarm checking in the native programming language of the front-end system, I/O poi

98、nt oriented systems typically have to implement this functionality in their </p><p>　　Besides this impact on the configuration side the processing and forwarding of alarms makes the difference between SCADA

99、and DCS systems. Since SCADA systems inherently do not ‘know’ about alarms, each alarm state must be polled either directly from the client application or in advanced cases from an event manager which will forward alarm

100、states to the clients. In any case a lot of overhead for ‘just’ checking alarm limits. DCS system again have the advantage that clients can either register the</p><h4>　　3 Trending and Archiving </h2>

101、<p>　　Trending has become an important business in control systems architectures. Trends are necessary to trace error conditions or for post mortem and performance analysis of the controlled plant. Besides some cus

102、tom implementations which are capable to store the data of complete control objects, most of the trending tools archive scalar data. Additional features like conditional trending or correlation plots make up the differen