Virtual Instruments Based on Reconfigurable Logic
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 function. 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 signal of the analysis and processing to complete a variety of control and test function. The user through the application of general-purpose computer program modules and features of the hardware together. Through friendly graphical interface to operate this computer. As in operating their own definition of inpidual instruments of their own design can be measured to complete the acquisition, analysis, determine, control, display, data storage and so on.
Virtual Instruments advantages of more traditional instruments:
(1)A strong integration of computer hardware resources. Breaking the traditional instruments in data processing, display, storage and other limitations, and
greatly enhanced the capabilities of traditional instruments.
(2)The use of computer 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. Directly on the test data for various analysis and processing in time. Through the graphical user interface technology, truly user-friendly, human-computer interaction.
(3)Hardware and software of virtual 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 is more flexible, efficient and shorten the formation time of the system
The traditional instruments are application specific systems based on fixed hardware and software resources so their function and applications are defined by the manufacturer. These instruments are complex systems and therefore they become expensive and difficult to manage.
The widespread usage of personal computers 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 computer 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 computers 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 common operating 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 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 computer and rising the maximum sample rate.
基于虚拟仪器的可重构逻辑
虚拟仪器的出现是测量仪器发展历史上的一场革命。它充分利用最新的计算机技术来实现和扩展仪器的功能，用计算机屏幕可以简单地模拟大多数仪器的调节控制面板，以各种需要的形式表达并且输出检测结果，用计算机软件实现大部分信号的分析和处理,完成大多数控制和检测功能。用户通过应用程序将一般的通用计算机与功能化模块硬件结合起来,通过友好的界面来操作计算机,就像在操作自己定义，自己设计的单个仪器,可完成对被测量的采集，分析，判断，控制，显示，数据存储等。
虚拟仪器较传统仪器的优点
(1)融合计算机强大的硬件资源,突破了传统仪器在数据处理，显示，存储等方面的限制，大大增强了传统仪器的功能。
(2)利用计算机丰富的软件资源，实现了部分仪器硬件的软件化，节省了物质资源，增加了系统灵活性。通过软件技术和相应数值算法，实时，直接地对测试数据进行各种分析与处理，通过图形用户界面技术,真正做到界面友好、人
机交互。
(3)虚拟仪器的硬件和软件都具有开放性，模块化，可重复使用及互换性等特点。因此，用户可根据自己的需要，选用不同厂家的产品,使仪器系统的开发更为灵活，效率更高，缩短系统组建时间。
传统的仪器是以固定的硬件和软件资源为基础的specific系统， 这使得系统的功能和应用程序由制造商定义。这些仪器都是复杂的系统，因此它们变得昂贵而且难以操作和管理。个人电脑在许多科技领域的广泛应用使其为测量仪器的执行搭建了一个理想的硬件和软件平台，通过增加一个简单的数据采集系统，个人计算机可以仿真任何仪器。因为它们没有独自占有和访问硬件和软件资源，所以以这种方式产生的仪器被称为虚拟仪器。不同的仪器只要对该软件重新编程就可以在同一硬件中实现。虚拟仪器呈现了大量的优势，其中最重要的就是由于硬件和软件资源的重用性降低了成本。上述特点及虚拟仪器的不断发展和个人电脑降价使虚拟仪器成为传统仪器的一个有价值的替代。
然而，也有两个主要因素限制了虚拟仪器的应用。一方面，数据捕获的减少将放缓速度，因为一般用途的电脑普遍常用的操作系统并不面向实时应用。另一方面，数据采集系统不是应用导向系统而是一个通用的系统。因此，我们建议的重点是由通用硬件更换可重构数据采集系统来加强虚拟仪器，它如图1所示。通过这种方式，一些数据的处理过程可以通过减少计算机上硬件数据流和上升的最大采样率来实现。