【正文】 sources so their function and applications are defined by the manufacturer. These instruments are plex systems and therefore they bee expensive and difficult to manage. The widespread usage of personal puters in many 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 puter can emulate any 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 hardware by only reprogramming the software. The virtual instruments offer plenty of advantages the most important of which is the low cost due to the reusability of hardware and software resources. The above characteristics and the continuous evolution and cheapening of the personal puters make the virtual instruments a valuable alternative to traditional ones. 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 mon operating systems of the general purpose puters 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 on the enhancement of virtual instruments by the replacement of the generic hardware with a reconfigurable data acquisition system, as it is shown in Figure 1. By this way, some data process can be implemented by hardware reducing the data flow to/from the puter and rising the maximum sample rate. The benefits of virtual instruments based on reconfigurable logic are the following: The bandwidth of the instruments can be increased implementing the more time critical algorithms by hardware. The input/output capacity can be reconfigured according to the application. In special, 中原工學(xué)院信息商務(wù)學(xué)院外文翻譯 11 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 puter interface can be reconfigured according to the available resources (Plugamp。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。 4. 虛擬儀器的發(fā)展方向 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。 提供了豐富的數(shù)據(jù)采集、分析及存儲(chǔ)的庫(kù)函數(shù)。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。 幾個(gè)采用賽靈思（ XC400E）和 Altera（ FLEX10K）的原型版開(kāi)發(fā)了一個(gè)虛擬邏輯（國(guó)家和時(shí)間）分析儀的實(shí)現(xiàn)。該單元實(shí)現(xiàn)了更加重要的算法 中原工學(xué)院信息商務(wù)學(xué)院外文翻譯 5 來(lái)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）。 定時(shí)模塊 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。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。這個(gè)硬件與通用的可重構(gòu)虛擬儀器系統(tǒng)的計(jì)算機(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。 虛擬儀器系統(tǒng)主要由計(jì)算機(jī)、硬件板卡、軟件及附件組成。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 實(shí)時(shí)應(yīng)用。 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。 虛擬儀器的出現(xiàn)是測(cè)量?jī)x器發(fā)展歷史上的一場(chǎng)革命。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。通過(guò)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(guò)圖形用戶界面技術(shù) ,真正做到界面友好、人機(jī)交互。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。在特殊情況下的 FPGA 器件的特點(diǎn)是通過(guò)大量輸入 /輸出引腳提供的能力來(lái)觀察和控制的全數(shù)字信號(hào)的虛擬儀器。虛擬儀器本質(zhì)上是一個(gè)開(kāi)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(lái)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。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 。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。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)。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，并允許了設(shè)備之間的物理隔離。 中原工學(xué)院信息商務(wù)學(xué)院外文翻譯 6 2 虛擬儀器的概念 虛擬儀器 (Virtual Instrument，簡(jiǎn)稱 VI)的概念是由美國(guó)國(guó)家儀器公司 (NI)在 20 世紀(jì) 80 年代最早提出的。目前，該開(kāi)發(fā)軟件在國(guó)際測(cè)試、測(cè)控行業(yè)比較流行，在國(guó)內(nèi)的測(cè)控領(lǐng)域也得到廣泛應(yīng)用。 強(qiáng)大的 Inter 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(kāi)發(fā)。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，學(xué)校財(cái)力難以支付，也不符合目前學(xué)校的實(shí)際。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(gòu)置、維護(hù)費(fèi)用高。 LABVIEW software development platform has the following advantages： 1. It use graphical programming approach, the designer do not need to write any code in text format, It is the true language of engineers. 2. It provides a wealth of data collection, analysis and storage of the library functions. 3. Provides both the traditional debugging tools, such as setting 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 debugging and development of more is convenient. 4. The 32bit piler generates 32bits piled program to ensure that user data acquisition, test and measurement solutions for highspeed implementation. 5. Include the functions of the munication bus in DAQ, GPIB, PXI, VXI, RS232/485 and other kind of equipment, making the developer who do not know the different bus stand can driver the interface devices and instruments 6. Provide a substantial amount of code or software for connecting external mechanisms, such as DLL (dynamic link library), DDE (shared libraries), ActiveX and so on. 7. Powerful Inter capabilities, support for mon work protocols to 中原工學(xué)院信息商務(wù)學(xué)院外文翻譯 16 facilitate working , remote monitoring and control equipment development. Graphical program programming is simple and intuitive, the development and high efficiency. With the continuous development of virtual instrumentation and graphical programming language, test and control areas will bee the most popular trends. The development direction of virtual instrument As a new instruments, the advantage of the virtual instruments is that userdefined f