基于虛擬儀器的可重構(gòu)邏輯外文翻譯

1、<p><b>　　畢業(yè)論文（設(shè)計(jì)）</b></p><p><b>　　外文翻譯</b></p><p>　　題 目： 基于虛擬儀器的可重構(gòu)邏輯 </p><p>　　系部名稱： 專業(yè)班級(jí)： </p><p>　　學(xué)

2、生姓名： 學(xué) 號(hào)： </p><p>　　指導(dǎo)教師： 教師職稱： </p><p>　　2013 年 3月22 日</p><p><b>　　一、漢語翻譯</b></p><p>　　基于虛擬儀器的可重構(gòu)邏輯</p&g

3、t;<p>　　摘要：從使用一個(gè)一般組合的通用計(jì)算機(jī)數(shù)據(jù)采集系統(tǒng)得出結(jié)果的虛擬儀器是為了仿真一個(gè)傳統(tǒng)的測(cè)量儀器。該虛擬儀器的數(shù)據(jù)采集硬件提供電腦的輸入/輸出功能，通常以有固定架構(gòu)的標(biāo)準(zhǔn)電路為基礎(chǔ)。與此同時(shí)，軟件定義的分析和處理所獲得的數(shù)據(jù)是生成的虛擬儀器的功能。因此，虛擬儀器的特點(diǎn)是多功能性，成本低，但它們程序的性能缺乏面向應(yīng)用的硬件架構(gòu)。在本文中，我們提出了虛擬儀器系統(tǒng)在可重構(gòu)硬件基礎(chǔ)上改善了維護(hù)其多功能性虛擬儀器的特征

4、和低成本。 </p><p><b>　　1.引言 </b></p><p>　　虛擬儀器的出現(xiàn)是測(cè)量儀器發(fā)展歷史上的一場(chǎng)革命。它充分利用最新的計(jì)算機(jī)技術(shù)來實(shí)現(xiàn)和擴(kuò)展儀器的功能，用計(jì)算機(jī)屏幕可以簡單地模擬大多數(shù)儀器的調(diào)節(jié)控制面板，以各種需要的形式表達(dá)并且輸出檢測(cè)結(jié)果，用計(jì)算機(jī)軟件實(shí)現(xiàn)大部分信號(hào)的分析和處理,完成大多數(shù)控制和檢測(cè)功能。用戶通過應(yīng)用程序?qū)⒁话愕耐ㄓ糜?jì)算機(jī)與

5、功能化模塊硬件結(jié)合起來,通過友好的界面來操作計(jì)算機(jī),就像在操作自己定義，自己設(shè)計(jì)的單個(gè)儀器,可完成對(duì)被測(cè)量的采集，分析，判斷，控制，顯示，數(shù)據(jù)存儲(chǔ)等。</p><p>　　虛擬儀器較傳統(tǒng)儀器的優(yōu)點(diǎn)</p><p>　　(1)融合計(jì)算機(jī)強(qiáng)大的硬件資源,突破了傳統(tǒng)儀器在數(shù)據(jù)處理，顯示，存儲(chǔ)等方面的限制，大大增強(qiáng)了傳統(tǒng)儀器的功能。</p><p>　　(2)利用計(jì)算機(jī)豐富

6、的軟件資源，實(shí)現(xiàn)了部分儀器硬件的軟件化，節(jié)省了物質(zhì)資源，增加了系統(tǒng)靈活性。通過軟件技術(shù)和相應(yīng)數(shù)值算法，實(shí)時(shí)，直接地對(duì)測(cè)試數(shù)據(jù)進(jìn)行各種分析與處理，通過圖形用戶界面技術(shù),真正做到界面友好、人機(jī)交互。</p><p>　　(3)虛擬儀器的硬件和軟件都具有開放性，模塊化，可重復(fù)使用及互換性等特點(diǎn)。因此，用戶可根據(jù)自己的需要，選用不同廠家的產(chǎn)品,使儀器系統(tǒng)的開發(fā)更為靈活，效率更高，縮短系統(tǒng)組建時(shí)間。</p>

7、<p>　　傳統(tǒng)的儀器是以固定的硬件和軟件資源為基礎(chǔ)的specific系統(tǒng)， 這使得系統(tǒng)的功能和應(yīng)用程序由制造商定義。這些儀器都是復(fù)雜的系統(tǒng)，因此它們變得昂貴而且難以操作和管理。個(gè)人電腦在許多科技領(lǐng)域的廣泛應(yīng)用使其為測(cè)量儀器的執(zhí)行搭建了一個(gè)理想的硬件和軟件平臺(tái)，通過增加一個(gè)簡單的數(shù)據(jù)采集系統(tǒng)，個(gè)人計(jì)算機(jī)可以仿真任何儀器。因?yàn)樗鼈儧]有獨(dú)自占有和訪問硬件和軟件資源，所以以這種方式產(chǎn)生的儀器被稱為虛擬儀器。不同的儀器只要對(duì)該軟件重新

8、編程就可以在同一硬件中實(shí)現(xiàn)。虛擬儀器呈現(xiàn)了大量的優(yōu)勢(shì)，其中最重要的就是由于硬件和軟件資源的重用性降低了成本。上述特點(diǎn)及虛擬儀器的不斷發(fā)展和個(gè)人電腦降價(jià)使虛擬儀器成為傳統(tǒng)儀器的一個(gè)有價(jià)值的替代。</p><p>　　然而，也有兩個(gè)主要因素限制了虛擬儀器的應(yīng)用。一方面，數(shù)據(jù)捕獲的減少將放緩速度，因?yàn)橐话阌猛镜碾娔X普遍常用的操作系統(tǒng)并不面向?qū)崟r(shí)應(yīng)用。另一方面，數(shù)據(jù)采集系統(tǒng)不是應(yīng)用導(dǎo)向系統(tǒng)而是一個(gè)通用的系統(tǒng)。因此，我們建

9、議的重點(diǎn)是由通用硬件更換可重構(gòu)數(shù)據(jù)采集系統(tǒng)來加強(qiáng)虛擬儀器，通過這種方式，一些數(shù)據(jù)的處理過程可以通過減少計(jì)算機(jī)上硬件數(shù)據(jù)流和上升的最大采樣率來實(shí)現(xiàn)。</p><p>　　基于可重構(gòu)邏輯的虛擬儀器好處如下： </p><p>　　-該儀器的帶寬可以提高，為在硬件上實(shí)現(xiàn)關(guān)鍵算法提供更多的時(shí)間。</p><p>　　-輸入/輸出的容量根據(jù)不同的應(yīng)用可以重新配置。在特殊情況下

10、的FPGA器件的特點(diǎn)是通過大量輸入/輸出引腳提供的能力來觀察和控制的全數(shù)字信號(hào)的虛擬儀器。 </p><p>　　-計(jì)算機(jī)接口可根據(jù)現(xiàn)有的資源重新配置（即插即用外設(shè)）。 </p><p>　　-不同的儀器可以共享軟件和硬件設(shè)計(jì)模塊提高了它們的可重用性。 </p><p>　　2.虛擬儀器的組成及分類</p><p>　　虛擬儀器系統(tǒng)主要由計(jì)算

11、機(jī)、硬件板卡、軟件及附件組成。用戶可以根據(jù)要求靈活地構(gòu)建自己的測(cè)試儀器。</p><p>　　虛擬儀器的核心是軟件，它主要由硬件驅(qū)動(dòng)程序、系統(tǒng)操作平臺(tái)、應(yīng)用編程軟件等組成，可完成所有的測(cè)試要求。目前開發(fā)環(huán)境主要有兩類：(1)文本語言；(2)圖形語言。由于圖形語言開發(fā)的方便性,受到了廣大工程師的歡迎，一個(gè)在計(jì)算機(jī)語言方面沒有很多訓(xùn)練的工程師，也可在短時(shí)間內(nèi)掌握虛擬儀器開發(fā)的技術(shù)，并且應(yīng)用到工程實(shí)踐中。虛擬儀器本質(zhì)上

12、是一個(gè)開放型的結(jié)構(gòu)，由通用計(jì)算機(jī)、數(shù)字信號(hào)處理器或其它CPU 來提供信號(hào)處理、存儲(chǔ)和顯示功能，由數(shù)據(jù)采集板卡、GP IB 或VXI總線接口板進(jìn)行信號(hào)的獲取與控制，實(shí)現(xiàn)儀器的功能。根據(jù)它采用總線方式的不同，可分為以下幾種類型：</p><p>　　(1)PC總線—插卡型虛擬儀器</p><p>　　(2)并行口式虛擬儀器</p><p>　　(3)GB IB 總線方式

13、的虛擬儀器</p><p>　　(4)VXI總線方式虛擬儀器</p><p>　　(5)PXI總線方式虛擬儀器</p><p>　　3.可重構(gòu)數(shù)據(jù)采集系統(tǒng) </p><p>　　我們建議的執(zhí)行是使用FPGA設(shè)立一個(gè)可重構(gòu)數(shù)據(jù)采集系統(tǒng)。該系統(tǒng)的操作類似可重新配置的處理器的面向捕獲，同時(shí)產(chǎn)生和分析數(shù)字信號(hào)。這個(gè)硬件與通用的可重構(gòu)虛擬儀器系統(tǒng)的計(jì)算

14、機(jī)結(jié)果組合方式，最終確定用戶的軟件和每個(gè)特定應(yīng)用所需的硬件資源。 </p><p><b>　　3.1一般說明 </b></p><p>　　一個(gè)數(shù)據(jù)采集系統(tǒng)的更重要區(qū)塊如圖2所示。作為一個(gè)面向應(yīng)用的系統(tǒng)，根據(jù)不同的應(yīng)用，這些模塊的大部分必須是可伸縮的（增加或減少輸入/輸出引腳的數(shù)量）。例如，采集存儲(chǔ)器的內(nèi)存容量要根據(jù)儀器的要求來設(shè)定。同時(shí)，如果該設(shè)備提供足夠的資源，

15、一些儀器可以同時(shí)工作。在這種情況下，在圖2所示的結(jié)構(gòu)有些模塊必須相應(yīng)地成倍增加，而同時(shí)其他的模塊在儀器中則可以共享。例如，一個(gè)唯一的計(jì)算機(jī)接口模塊復(fù)用的時(shí)間比一般時(shí)間為更有效，因?yàn)檩^少的輸入/輸出引腳致力于通信任務(wù)。 </p><p>　　在計(jì)算機(jī)方面，該軟件是致力于存儲(chǔ)和數(shù)據(jù)可視化，并進(jìn)行配置和對(duì)硬件的控制。第一個(gè)任務(wù)是實(shí)施應(yīng)用水平，并利用多任務(wù)操作系統(tǒng)的優(yōu)勢(shì)和先進(jìn)的圖形界面。第二項(xiàng)任務(wù)主要實(shí)現(xiàn)了操作系統(tǒng)的擴(kuò)展

16、和在這方面他們通過硬件來緊密相連。此外，為這些框圖實(shí)現(xiàn)配置設(shè)備的特點(diǎn)（SRAM的FPGA）也進(jìn)行了描述。</p><p>　　3.2輸入/輸出模塊 </p><p>　　輸入/輸出模塊符合與現(xiàn)實(shí)世界的接口，輸入/輸出模塊可重構(gòu)設(shè)備必須是雙向的，并且具有三態(tài)功能和更快捕獲率的內(nèi)部寄存器。 </p><p><b>　　3.3采集控制塊 </b>&

17、lt;/p><p>　　數(shù)據(jù)采集通常是與一些外部或內(nèi)部的事件同步的，這一任務(wù)是由采集控制模塊開發(fā)。因此，這種控制由信號(hào)的輸入/輸出模塊和內(nèi)部邏輯的進(jìn)程變得非常重要。具有低偏移和大扇出分銷網(wǎng)絡(luò)的架構(gòu)是強(qiáng)制性的目的。 </p><p>　　同時(shí)，一些輸入和輸出往往有著共同的控制信號(hào)，因此攜帶控制信號(hào)的一個(gè)外圍總線的設(shè)備適合這種應(yīng)用。</p><p><b>　　3

18、.4定時(shí)模塊 </b></p><p>　　這個(gè)定時(shí)模塊（振蕩器，定時(shí)器和計(jì)數(shù)器）為數(shù)據(jù)采集系統(tǒng)提供內(nèi)部控制信號(hào)，特別注意計(jì)數(shù)器的設(shè)計(jì)，以達(dá)到最大的工作頻率。 </p><p><b>　　3.5內(nèi)存模塊 </b></p><p>　　內(nèi)存模塊作為一個(gè)采集/生成數(shù)據(jù)的臨時(shí)存儲(chǔ)區(qū)域。這種內(nèi)存塊通過計(jì)算機(jī)接口孤立地轉(zhuǎn)移數(shù)據(jù)采集的過程。因

19、此，這些存儲(chǔ)設(shè)備實(shí)現(xiàn)的功能，與擁有不同時(shí)鐘頻率推/彈出操作雙端口FIFO類似。 </p><p>　　該內(nèi)存模塊可以實(shí)現(xiàn)如內(nèi)部或外部單位的FPGA。第一種情況較為可取，因?yàn)樵O(shè)計(jì)提供了最佳的性能，功耗更低，而且更不容易出錯(cuò)。因此，擁有嵌入式雙端口內(nèi)存塊的FPGA更適合這些目的。 </p><p>　　3.6數(shù)據(jù)處理單元 </p><p>　　數(shù)據(jù)處理單元執(zhí)行的實(shí)時(shí)預(yù)處

20、理的數(shù)據(jù)采集。該單元實(shí)現(xiàn)了更加重要的算法來確定的數(shù)據(jù)吞吐量，同時(shí)其他單元可以轉(zhuǎn)達(dá)對(duì)軟件的控制（在電腦端）。</p><p>　　有詳盡分析的單元，其中算法必須在硬件上實(shí)現(xiàn)，同時(shí)必須在軟件中實(shí)現(xiàn)是為每一個(gè)不同的儀器。對(duì)于邏輯分析儀為例，觸發(fā)模式檢測(cè)邏輯必須在硬件中實(shí)現(xiàn)更好性能的同時(shí)，數(shù)據(jù)格式的數(shù)據(jù)轉(zhuǎn)換（裝配，拆卸），可以在計(jì)算機(jī)上完成。 </p><p><b>　　3.7計(jì)算機(jī)接

21、口 </b></p><p>　　對(duì)于可重構(gòu)的互連數(shù)據(jù)采集卡與計(jì)算機(jī)，有兩種不同的情況，一種是使用一個(gè)直接的擴(kuò)展/本地總線連接，而另一種是使用串行/并行通信接口。在第一種情況中，可以可以得到一個(gè)擁有很大數(shù)據(jù)吞吐量的儀器，但是這種接口會(huì)消耗FPGA的很多資源（邏輯和輸入/輸出引腳）并且限制之間聯(lián)網(wǎng)系統(tǒng)的物理距離。第二種情況中，串行/并行通信接口的限制了轉(zhuǎn)移的二進(jìn)制率，但消耗更少的邏輯和輸入/輸出資源，并

22、允許了設(shè)備之間的物理隔離。這最后一個(gè)特點(diǎn)對(duì)于便攜式儀器的實(shí)現(xiàn)來說是非常重要的，并隔離了采集硬件和嘈雜的環(huán)境通用計(jì)算機(jī)。</p><p>　　通過這個(gè)原因，開發(fā)的系統(tǒng)實(shí)際上是實(shí)現(xiàn)了標(biāo)準(zhǔn)的IEEE - 488（ECP模式）作為與計(jì)算機(jī)的通信接口。 </p><p><b>　　4.結(jié)論 </b></p><p>　　幾個(gè)采用賽靈思（XC400E）和

23、Altera（FLEX10K）的原型版開發(fā)了一個(gè)虛擬邏輯（國家和時(shí)間）分析儀的實(shí)現(xiàn)。一個(gè)超過五年的性能表現(xiàn)得到了使用了商業(yè)數(shù)據(jù)采集卡虛擬儀器的實(shí)現(xiàn)。 </p><p>　　1、虛擬儀器的產(chǎn)生背景</p><p>　　當(dāng)今我們處于一個(gè)正在高度發(fā)展的信息社會(huì)，要求在有限的時(shí)空上實(shí)現(xiàn)大量信息的交換，必然帶來信息密度的急劇增大，要求電子系統(tǒng)對(duì)于信息的處理速度越來越高，功能越來越強(qiáng)，這使得系統(tǒng)結(jié)構(gòu)日

24、趨復(fù)雜。一方面電子技術(shù)及市場(chǎng)的發(fā)展從客觀上要求測(cè)試儀器向自動(dòng)化及柔性化的方向發(fā)展，另一方面，電子技術(shù)及市場(chǎng)的發(fā)展也給虛擬儀器的產(chǎn)生提供了可能。在這種形式下，基于微計(jì)算機(jī)的虛擬儀器逐步變得現(xiàn)實(shí)，它的出現(xiàn)和廣泛使用為測(cè)試系統(tǒng)的設(shè)計(jì)提供一個(gè)極佳的模式，并且使工程師們?cè)跍y(cè)量和控制方面得到強(qiáng)大功能和靈活性。</p><p><b>　　2虛擬儀器的概念</b></p><p>

25、　　虛擬儀器(Virtual Instrument，簡稱VI)的概念是由美國國家儀器公司(NI)在20世紀(jì)80年代最早提出的。虛擬儀器就是在以通用計(jì)算機(jī)為核心的硬件平臺(tái)上，由用戶設(shè)計(jì)定義、具有虛擬前面板、測(cè)試功能由測(cè)試軟件實(shí)現(xiàn)的一種計(jì)算機(jī)儀器系統(tǒng)。其核心的思想是利用計(jì)算機(jī)的強(qiáng)大資源使本來需要硬件實(shí)現(xiàn)的技術(shù)軟件化，以便最大限度地降低系統(tǒng)成本，增強(qiáng)系統(tǒng)功能與靈活性。虛擬儀器代表著從傳統(tǒng)硬件為主的測(cè)試系統(tǒng)到以軟件為中心的測(cè)試系統(tǒng)的根本性轉(zhuǎn)變。

26、虛擬儀器的出現(xiàn)是儀器發(fā)展史上的一場(chǎng)革命，代表著儀器發(fā)展的最新方向和潮流，對(duì)科學(xué)技術(shù)的發(fā)展和工業(yè)生產(chǎn)的進(jìn)步將產(chǎn)生不可估量的影響。虛擬儀器具有性能高、擴(kuò)展性強(qiáng)、開發(fā)時(shí)間短、無縫集成等優(yōu)勢(shì)。</p><p>　　3. 圖形化虛擬儀器開發(fā)平臺(tái)—LABVIEW 簡介及其優(yōu)勢(shì)</p><p>　　LABVIEW是Laboratory Virtual Instrument Engineering Wor

27、kbench (實(shí)驗(yàn)室虛擬儀器集成開發(fā)環(huán)境)的簡稱，是由美國國家儀器公司(National instruments, IN)創(chuàng)立的一個(gè)功能強(qiáng)大而又靈活的儀器和分析應(yīng)用開發(fā)工具。Labview一種圖形化的編程語言，主要用來開發(fā)數(shù)據(jù)采集，儀器控制及數(shù)據(jù)處理分析等軟件，功能強(qiáng)大。目前，該開發(fā)軟件在國際測(cè)試、測(cè)控行業(yè)比較流行，在國內(nèi)的測(cè)控領(lǐng)域也得到廣泛應(yīng)用。函數(shù)信號(hào)發(fā)生器是在科學(xué)研究和工程設(shè)計(jì)中廣泛應(yīng)用的一種通用儀器。LABVIEW軟件開發(fā)平臺(tái)

28、具有以下優(yōu)點(diǎn): </p><p>　　1、圖形化的編程方式，設(shè)計(jì)者無需寫任何文本格式的代碼，是真正的工程師的語言。</p><p>　　2、提供了豐富的數(shù)據(jù)采集、分析及存儲(chǔ)的庫函數(shù)。</p><p>　　3、既提供了傳統(tǒng)的程序調(diào)試手段，如設(shè)置斷點(diǎn)、單步運(yùn)行，同時(shí)提供有獨(dú)到的高亮執(zhí)行工具，使程序動(dòng)畫式運(yùn)行，利于設(shè)計(jì)者觀察程序運(yùn)行的細(xì)節(jié)，使程序的調(diào)試和開發(fā)更為便捷

29、。</p><p>　　4、32bit的編譯器編譯生成32bit的編譯程序，保證用戶數(shù)據(jù)采集、測(cè)試和測(cè)量方案的高速執(zhí)行。</p><p>　　5、囊括了DAQ, GPIB, PXI, VXI, RS-232/485在內(nèi)的各種儀器通信總線標(biāo)準(zhǔn)的所有功能函數(shù)，使得不懂總線標(biāo)準(zhǔn)的開發(fā)者也能夠驅(qū)動(dòng)不同總線標(biāo)準(zhǔn)接口設(shè)備與儀器。</p><p>　　6、提供大量與外部代碼或

30、軟件進(jìn)行連接的機(jī)制，諸如DLL(動(dòng)態(tài)連接庫)、DDE(共享庫)、ActiveX等。</p><p>　　7、強(qiáng)大的Internet功能，支持常用網(wǎng)絡(luò)協(xié)議，方便網(wǎng)絡(luò)、遠(yuǎn)程測(cè)控儀器的開發(fā)。</p><p>　　圖形化程序設(shè)計(jì)編程簡單、直觀、開發(fā)效率高。隨著虛擬儀器技術(shù)的不斷發(fā)展，圖形化的編程語言必將成為測(cè)試和控制領(lǐng)域內(nèi)最流行的發(fā)展趨勢(shì)。</p><p>　　4. 虛擬儀

31、器的發(fā)展方向</p><p>　　虛擬儀器作為新興的儀器儀表，其優(yōu)勢(shì)在于用戶可自行定義儀器的功能和結(jié)構(gòu)等，且構(gòu)建容易、轉(zhuǎn)換靈活，它已廣泛應(yīng)用于電子測(cè)量、聲學(xué)分析、故障診斷、航天航空、機(jī)械工程、建筑工程、鐵路交通、生物醫(yī)療、教學(xué)及科研等諸多方面。</p><p>　　隨著計(jì)算機(jī)軟硬件技術(shù)、通信技術(shù)及網(wǎng)絡(luò)技術(shù)的發(fā)展，給虛擬儀器的發(fā)展提供了廣闊的天地，國內(nèi)外儀器界正看中這個(gè)大市場(chǎng)。測(cè)控儀器將會(huì)向

32、高效、高速、高精度和高可靠性以及自動(dòng)化、智能化和網(wǎng)絡(luò)化的方向發(fā)展。開放式數(shù)據(jù)采集標(biāo)準(zhǔn)將使虛擬儀器走上標(biāo)準(zhǔn)化、通用化、系列化和模塊化的道路。</p><p>　　虛擬儀器作為教學(xué)的新手段，已慢慢地走進(jìn)了電子技術(shù)的課堂和實(shí)驗(yàn)室，正逐漸改變著電子技術(shù)教學(xué)的傳統(tǒng)模式，這也是現(xiàn)代教育技術(shù)發(fā)展的必然。在電工電子實(shí)驗(yàn)室的建設(shè)中，實(shí)驗(yàn)室常規(guī)設(shè)備有的已經(jīng)老化，有的技術(shù)上有些落后，在當(dāng)前學(xué)校經(jīng)費(fèi)較少的情況下，如果配置常規(guī)儀器、儀表，

33、學(xué)校財(cái)力難以支付，也不符合目前學(xué)校的實(shí)際。而且，隨著測(cè)試儀器的數(shù)字化、計(jì)算機(jī)化的發(fā)展趨勢(shì)，傳統(tǒng)測(cè)試儀器漸漸有被取代的趨勢(shì)。如果運(yùn)用虛擬儀器技術(shù)，以微機(jī)為基礎(chǔ)，構(gòu)建集成化測(cè)試平臺(tái)，代替常規(guī)儀器、儀表，不但滿足電工電子實(shí)驗(yàn)教學(xué)的需要，而且將這批微機(jī)可作為其他有關(guān)計(jì)算機(jī)課程教學(xué)用機(jī)，大大提高了設(shè)備利用率，降低了實(shí)驗(yàn)室建設(shè)的成本。當(dāng)前應(yīng)該解決的是如何使虛擬儀器和現(xiàn)有儀器配合，挖掘現(xiàn)有儀器的潛力，達(dá)到逐步淘汰和取代傳統(tǒng)儀器的目的。</p&g

34、t;<p>　　總之，虛擬儀器有很廣闊的發(fā)展空間，并最終要取代大量的傳統(tǒng)儀器成為儀器領(lǐng)域的主流產(chǎn)品，成為測(cè)量、分析、控制、自動(dòng)化儀表的核心。</p><p><b>　　5.信號(hào)發(fā)生器概述</b></p><p>　　信號(hào)發(fā)生器(signal generator)又稱信號(hào)源或振蕩器，是一種能提供各種頻率、波形和輸出電平電信號(hào)，常用作測(cè)試的信號(hào)源或激勵(lì)源的

35、設(shè)備。在生產(chǎn)實(shí)踐和科技領(lǐng)域中有著廣泛的應(yīng)用。隨著現(xiàn)代電子、計(jì)算機(jī)和信號(hào)處理等技術(shù)的發(fā)展，極大促進(jìn)了數(shù)字化技術(shù)在電子測(cè)量儀器中的應(yīng)用，使原有的模擬信號(hào)處理逐步被數(shù)字信號(hào)處理所代替，從而擴(kuò)充了儀器信號(hào)的處理能力，提高了信號(hào)測(cè)量的準(zhǔn)確度、精度和變換速度，克服了模擬信號(hào)處理的諸多缺點(diǎn)，數(shù)字信號(hào)發(fā)生器隨之發(fā)展起來。傳統(tǒng)的信號(hào)發(fā)生器其功能完全靠硬件實(shí)現(xiàn)，功能單一而且用戶的購置、維護(hù)費(fèi)用高。更重要的是，對(duì)于傳統(tǒng)的信號(hào)發(fā)生器，其功能一旦確定便不能更改，

36、用戶要想使用新的功能則必須重新購買新的儀器，傳統(tǒng)信號(hào)發(fā)生器的不足是顯而易見的。虛擬儀器是將儀器技術(shù)、計(jì)算機(jī)技術(shù)、總線技術(shù)和軟件技術(shù)緊密的融合在一起，利用計(jì)算機(jī)強(qiáng)大的數(shù)字處理能力實(shí)現(xiàn)儀器的大部分功能，打破了傳統(tǒng)儀器的框架，形成的一種新的儀器模式。</p><p>　　本文摘譯自： Computing Paradigm.ISBN:3-540-64948-4</p><p><b>　

37、　二、英語原文</b></p><p>　　Virtual Instruments Based on Reconfigurable Logic</p><p>　　Abstract. A virtual instrument results from the combination of a general purpose computer with a generic dat

38、a acquisition system in order to emulate a traditional measurement instrument. The data acquisition hardware of the virtual instruments provides computers with input/output capability and is usually based on the integrat

39、ion of standard circuits with fixed architecture. Meanwhile the software defines the analysis and processing of the acquired data that is the function of the generated virt</p><p>　　1. Introduction</p>

40、<p>　　The emergence of virtual instrumentation is a revolution in the history of the development of measuring instruments. It fully utilizes the latest computer technology to implement and extend the instrument fu

41、nction. Using the image of a computer screen can be easily simulate a variety of equipment control panels to the needs expressed in the form of the output of test results. Using computer software to achieve most of the s

42、ignal of the analysis and processing to complete a variety of control and</p><p>　　Virtual Instruments advantages of more traditional instruments: </p><p>　　(1)A strong integration of computer h

43、ardware resources. Breaking the traditional instruments in data processing, display, storage and other limitations, and greatly enhanced the capabilities of traditional instruments. </p><p>　　(2)The use of c

44、omputer software resources to achieve some part of the software of instrument hardware, saving material resources, increase system flexibility. Through software technology and the corresponding numerical algorithm. Direc

45、tly on the test data for various analysis and processing in time. Through the graphical user interface technology, truly user-friendly, human-computer interaction. </p><p>　　(3)Hardware and software of virtu

46、al instrument is an open, modular, reusable and interchangeability characteristics. Therefore, the user can according to their own needs and use different manufacturers products. The development of the instrument system

47、is more flexible, efficient and shorten the formation time of the system</p><p>　　The traditional instruments are application specific systems based on fixed hardware and software resources so their function

48、 and applications are defined by the manufacturer. These instruments are complex systems and therefore they become expensive and difficult to manage.</p><p>　　The widespread usage of personal computers in ma

49、ny scientific and technological fields make them an ideal hardware and software platform for the implementation of measurement instruments. By adding a simple data acquisition system, a personal computer can emulate any

50、instrument. The instruments generated in this way are called virtual instruments because they do not have exclusive access to hardware and software resources. Different instruments can be implemented over the same hardwa

51、re by only r</p><p>　　Nevertheless, there are two main factors which limits the application of virtual instruments. By one hand, the data capture is reduce to slow rates because of the more common operating

52、systems of the general purpose computers are not oriented to realtime applications. By other hand, the data acquisition system is not an application oriented system but a generic one. Therefore, our proposal is focused o

53、n the enhancement of virtual instruments by the replacement of the generic hardware with a reco</p><p>　　The benefits of virtual instruments based on reconfigurable logic are the following:</p><p&

54、gt;　　-The bandwidth of the instruments can be increased implementing the more time critical algorithms by hardware.</p><p>　　-The input/output capacity can be reconfigured according to the application. In sp

55、ecial, FPGAs devices are characterized by a great number of input/output pins providing virtual instrument with the capacity to observe and control a wide number of signals.-The computer interface can be reconfigured ac

56、cording to the available resources (Plug&Play peripherals).</p><p>　　-Different instruments can share software and hardware design modules increasing their reusability.</p><p>　　2. The compo

57、sition and classification of virtual instruments </p><p>　　Virtual instrument system mainly consists of computers, hardware board,software and accessories. Users can request the flexibility to build their ow

58、n testing equipment.</p><p>　　The core of virtual instrument is software, which is mainly provided by the hardware driver, application programming software etc. It can complete all the test requirements. The

59、 current development environment mainly into two categories:(1) text language; (2) graphics language. As the graphic language developed by convenience welcomed by the majority of engineers. There are not many trained in

60、computer language engineers able to master the development of virtual instrument technology and applied</p><p>　　(1) PC Bus - plug-in card-based virtual instrument</p><p>　　(2) parallel port vir

61、tual instruments </p><p>　　(3) the way of GB IB bus virtual machines </p><p>　　(4) VXI bus mode Virtual Instrument </p><p>　　(5) PXI bus mode virtual instruments</p><p>

62、;　　3. Reconfigurable Data Acquisitions Systems</p><p>　　We propose the implementation of a reconfigurable data acquisition system using FPGAs. This system operates like a reconfigurable coprocessor oriented

63、to the capture, generation and analysis of digital signals. The combination of this hardware with a general purpose computer results in a reconfigurable virtual instrumentation system where the end user determines the so

64、ftware and hardware resources required for each particular application.</p><p>　　3.1 General Description</p><p>　　The more essential blocks of a data acquisition system are represented in Figure

65、 2. As an application oriented system, most of these modules must be scalable (increasing or decreasing the number of input/output pins) according to different applications. For example, the capacity of the acquisition m

66、emory varies with the requirements of the instrument.</p><p>　　At the same time, if the device provides with enough resources, several instruments can be active simultaneously. In this case, some blocks of t

67、he structure shown in Figure 2 must be multiplied accordingly while others can be shared among instruments. For example, an unique computer interface block multiplexed in time is generally more efficient because less inp

68、ut/output pins are dedicated to the communication tasks.</p><p>　　In the computer side, the software is dedicated to the storage and visualization of data, and also to the configuration and control of the ha

69、rdware. The first tasks are implemented at application level and take advantage of multitask operating systems and their advanced graphic interfaces. The second tasks are mainly implemented as extensions of the operative

70、 systems and in this way they are closely linked to the hardware.</p><p>　　The blocks represented in Figure 2 are briefly described in the next sections. Also, the characteristics of the configurable devices

71、 (SRAM FPGAs) required for the implementation of these blocks are indicated.</p><p>　　3.2 Input/Output Modules</p><p>　　The input/outputs modules conform the interface with the real world. The i

72、nput/output blocks of the reconfigurable device must be bidirectional, with tri-state capability and internal registers for faster capture rates.</p><p>　　3.3 Acquisition Control Block</p><p>　　

73、The data capture is usually synchronized with some external or internal events and this task is developed by the acquisition control module. As a consequence, the routing of this control signals to the input/output block

74、s and to the internal logic becomes very important. An architecture with several low skew and great fan-out distribution networks is mandatory for this purposes.</p><p>　　At the same time, several inputs and

75、 outputs usually share common control signal so a device with a peripheral bus carrying control signals is suitable for this application.</p><p>　　3.4 Timing Blocks</p><p>　　The timing blocks (o

76、scilator, timers and counters) provides internal control signals to the data acquisition system. Special attention was dedicated to the design of counters in order to reach maximum operating frequencies.</p><p

77、>　　3.5 Memory Blocks</p><p>　　The memory blocks operate as a temporary storage of the acquired/generated data. This memory blocks isolate the data acquisition process from the transference through the com

78、puter interface. Therefore these storage devices are implemented as dual-port FIFOs with different clocks for push/pop operations.</p><p>　　The memory blocks can be implemented like internal or external unit

79、s to the FPGA. The first case is more desirable because the design offers best performance, consumes less power and is less error prone. Therefore, the FPGAs with embedded dual port memory blocks are more suitable for th

80、ese purposes.</p><p>　　3.6 Data Processing Unit</p><p>　　The data processing unit performs a real-time pre-processing of the acquired data. This unit implements the more critical algorithms that

81、 determine the data throughput while the others can relay over software control (in the computer side). </p><p>　　An exhaustive analysis of which algorithms must be implemented in hardware and which must be

82、implemented in software was made for each different instrument. For example in a logic analyzer, the detection logic of the trigger patterns must be implemented in hardware for better performance meanwhile the data conve

83、rsion formats of data (assembling, disassembling) can be done in the computer.</p><p>　　3.7 Computer Interface</p><p>　　There are two different options for the interconnection of the reconfigura

84、ble data acquisition board with the computer, one using of a direct expansion/local bus connection and the other using of a serial/parallel communications interface. In the first case, instruments with a great data throu

85、ghput can be obtained but this kind of interface consumes many resources of the FPGA (logic and input/output pins) and limits the physical distance between the interconnected systems. On the opposite side, </p>&l

86、t;p>　　4. Conclusions</p><p>　　Several prototype boards using Xilinx (XC400E) and Altera (FLEX10K) were developed for the implementation of a virtual logic (state and timing) analyzer. A performance of mor

87、e than five was obtained over virtual instruments implemented using a commercial data acquisition board.</p><p>　　1、The generation background of virtual instrument</p><p>　　Today we ar

88、e in a highly developed information society, which require a limited time and space to achieve a large  amount of information exchange, inevitably bring about the rapid increase of

89、 information density，required the electronic systems have a faster speed and more powerful function for information processing. On the one hand the development of electronic technology and market requireme

90、nts objectively make the test instrument develop to the direction of automation and flexible, On the oth</p><p>　　2 、The concept of virtual instrument</p><p>　　Virt

91、ual Instruments (Virtual Instrument, referred to as VI) concept is first proposed by the National Instruments (NI) in 1980s' . The virtual instrument is a kind of Computer equipment system which based on the general

92、 purpose computer as the core hardware platform, defined by the user with a virtual front panel, the test function is performed by a computer testing software. The core idea is to use a powerful computer resources that

93、 would otherwise require hardware to software of the technol</p><p>　　3、graphical virtual instrument development platform-LABVIEW introduction and its advantages </p><p>　　LABVIEW is short

94、for Laboratory Virtual Instrument Engineering Workbench, it is a powerful and flexible instrumentation and analysis of application development tool created by National Instruments (National instruments, IN) 。Labview is a

95、 graphical programming language, mainly used to develop data acquisition, instrument control and data processing and analysis software. Currently, the development of software is popular in the international test, measure

96、ment and control industry , measurement and</p><p>　　It use graphical programming approach, the designer do not need to write any code in text format, It is the true language of 

97、;engineers.</p><p>　　It provides a wealth of data collection, analysis and storage of the library functions.</p><p>　　Provides both the traditional debugging tools, such as s

98、etting breakpoints, single step, while providing a unique tool for highlighting the implementation of that program to run the animation style, which will help designers to observe the details of running, so that debuggin

99、g and development of more is convenient.</p><p>　　The 32bit compiler generates 32bits compiled program to ensure that user data acquisition, test and measurement solutions&

100、#160;for high-speed implementation.</p><p>　　Include the functions of the communication bus in DAQ, GPIB, PXI, VXI, RS-232/485 and other kind of equipment, making the developer who do not know the di

101、fferent bus stand can driver the interface devices and instruments </p><p>　　Provide a substantial amount of code or software for connecting external mechanisms, such as DLL (dynamic link library), DDE (shar

102、ed libraries), ActiveX and so on.</p><p>　　Powerful Internet capabilities, support for common network protocols to facilitate networking , remote monitoring and control equipment development.</p><

103、;p>　　Graphical program programming is simple and intuitive, the development and high efficiency. With the continuous development of virtual instrumentation and graphical programming langu