the instrument category, Furthermore,we belleve that remote operation of an instrument, (e.g. digital voltmeter),interfaced to a computer does not necessarily make it a Virtual ,a instrument.There are usually two operating modes available: remote or local, as in the IEEE 一 488 system. Instead of a DAQ board, a virtual instrument can incorporate stand?alone devices, inlerfaced to the chosen PC bus,via cable and providing the same functionality as a DAQ board.Such data acquisition devices are often delivered under brand names,such as WaveBook(designed for PC operation only),or LogBook(operating as a PC peripheral or Stand-alone)from IOtech. In addition to a computer, a DAQ board and a connector,as shown in Figure
  3.
  12,virtual instrument-based measurement system hardware may and usually does include additional components: A conditioner card to match the input levels to the DAQ board's input range; A conditoner card for temperature, pressure, or displacement sensors; Expansion cards to provide additional analog inputs, high-volatage inputs, or lowvoltage inptus; An optically isolated analog/digital input card; A BNC coax input card; A low pass filter card or other cards. Figurse
  3.13 show a measurement system with a virtual instrument and additional cards. An adapter board is used to connect more than one conditioner card or expansion card to the DAQ board input. A virtual instrument-based measurement system, as show in Fiure
  3.13, can be used to measure and process various phsical qualities(e.g., Temperature, pressure, or displacement) and electrical signals spanning a wide range. means of By limited technical resources. The measurement performance of such a system depends not only on specifications of the boards used, but also on the characteristics.of the system's application software.By using signal filtration and averaging,statistical calculations.and other procedures,the quality of final measurement results may be significantly improved. 2 Programming of Measurement Systems and Virtual Instruments Software is an indispensable part of a computer?based measurement system and of a virtual instrument.High?level graphical programming languages,known as measurement system development environments,provide extensive software development capabilities and Make it easy to program a measurement system or a virtual instrument.Furthermore.the major instrumentation manufacturers offer proprietary programmiug languages (environments).such as LabVIEW or LabWindows from National Instruments,VEE (formerly HP VEE)from Agilent Technologies.and TestPoint from Keithlev. All these languages have a number of advantages but they are rather expensive.The price is several thousand dollars for a basic version.Graphically rich general?purpose programming languages,such as Visual C++or Visual Basic,and commands from the list 0f Standard Commands for Programmable Inst ruments (SCPI), can also be used to develop virtual Instrument software. LabVIEW, LabWindows, VEE.and TestPoint all come with libraries Of drivers for specific instruments, such as multimeters, digi tal oscilloscopes,analyzers, DAQ boards,and generators. Insturmentation manufacturers ensure that the drivers for
Their instruments are available in the the libraries of most popular development environment。 The deveIopment issues arc so elaborate that each package comes with a two-volume documenttation and requires a comprehensiVe manual. 3 Soflware Development in the LabVIEW Environment
The Principles of developing measurement system(or virtual instrument)software in a develoPment enbironment are described briefly in the example of using LabVIEW to build a virtual instrument(a spectrunl analyzer)with a DAQ board. Each software developed in LabVIEW consists of two main parts: .The Graphical User Interface(GUI),which provides an integrated front paneI of the instruments making up the measurement system or Virtual instrument Figure3?14 shows a sample front panel of a virtual spectrum analyzer in LabVIEW
  7; . The functional diagram(block diagram), which maps the function block icons and relations between these function blocks of the virtual instrument. See Figure 3?1 5 for a block diagram of a spectrum analyzer.This block diagram is the source code of the virtual instrument control program. To write a program in LabVIEW,a block diagram is created by dragging and dropping Object icons function icons fmm the All Functions palette,as shown in Figurc
  3.
  16, and the All Controls palette, as shown in Figure
  3.1
  7,onlo the panel. Many of these functions in the diagram can be expanded on multiple levels to set their Required properties. Surrounding the selected objects with a loop forces a conditional execution or repetition of the selected operations, corresponding to the effect of if or while instructions known from other programming languages . Instrument drivers which are necessary for the program to run should be stored in the LabVIEW driver library.Once the icon of a specific instrument is placed on the system diagram, as shown in Figure
  3.15, the program will use that that instrument's driver at runtime. Figure
  3.48 shows the expanded view of program menus that must be insret the HP34401A digital mulatimeter dirver form Hewlett-Packard into the system. Creating control programs in VEE or TestPoint is similar to the technique described earlier.
  •  
 

相关内容

英语口语6

   16天记住 天记住7000考研词汇(第一天) 考研词汇( 天记住 考研词汇 第一天) 1.With my own ears I clearly heard the heart beat of the nuclear bomb. 我亲耳清楚地听到原子弹的心脏的跳动。 2. Next year the bearded bear will bear a dear baby in the rear. 明年,长胡子的熊将在后方产一头可爱的小崽. 3. Early I searched through ...

中考英语60句练习

   2011 届常见中考句式练习 京育第 8 课时 届常见中考句式练习 练习?京育第 11 月 27 日 1. 一到家我就给你打电话。 home. 一到家我就给你打电话。 2.这部电影和那部电影一样有趣。 This film 这部电影和那部电影一样有趣。 这部电影和那部电影一样有趣 3. 我们在英语课上应该尽可能地多讲英语。 我们在英语课上应该尽可能地多讲英语。 We should in English classes. 4.当你迷路时,你可以向警察需求帮助。 当你迷路时,你可以向警察需求帮助。 ...

常用跟单英语60条

   非常抱歉,该文档存在转换错误,不能在本机显示。建议您重新选择其它文档 ...

外贸跟单英语60句

   外贸跟单英语 60 句 1.What’s the size?多大尺寸? 90X90 (Ninety by ninety)九十乘九十。 2.What’s the CMB? 体积多大? 0.07M3 (zero point zero seven cube meter) 0.07 立方米。 3.What’s the best/last price? 最低价是多少? ¥2.5 (Two point five)] 两块五。 4.How many designs?有几个款式? 3 designs .三个 ...

学位英语常考短语600个

   学位英语常考短语 600 个 英语词汇 2009-06-25 16:09 阅读 902 评论 1 字号: 大 中 小 1. abide by(=be faithful to ; obey)忠于;遵守. 2. be absent from…. 缺席,不在 3. absence or mind(=being absent-minded) 心不在焉 4. absorb (=take up the attention of) 吸引…的注意力 (被动语态) absorbed i n 全神贯注于… be ...

正版_初中英语60个中考句型

   大腾外语中考复习资料 英语 初中英语 57 个中考必备句型 1 as soon as 2 as…as 3 as…as possible 4 ask sb. for sth. 5 ask/tell sb. (how) to do sth. 6 ask/tell sb. (not) to do sth. 7 be afraid of doing/that 8 be busy doing sth. 9 be famous/late/ready/sorry for… 10 be glad that ...

职场英语60个办公室英语单词

   职场英语:60 职场英语:60 个单词拿下办公室英语 修改胶带 correction tap 书立 book stand 日记簿 diary book 文件袋 expanding file 地球仪 globe 名片夹 name card holder 办公用大头针 office pin 工字针 paper fastener 切纸刀 paper cuter 美工刀 cutter 总公司 Head Office 分公司 Branch Office 营业部 Business Office 人事部 ...

航海英语6050之--02航海图书资料

   二航海图书资料 02.1 航路指南 [101]While steaming slowly in the harbor,no ship is to exceed the speed limited. A. assumed B. appreciated C. promised D. permitted. KEY: D [102]Place names used on board ships should be those . A. specified by international author ...

航海英语6050之--20沿海航海技术

   二十沿海航海技术 20.1 船舶规范 [5151]When and where your Registry Certificate issued? A. is B. are C. was D. were KEY: C [5152]This certificate was issued {under} the provisions. A. according to B. with C. for D. below KEY: A [5153]The Tonnage Certificate gives ...

航海英语6050之--13船舶及其结构

   十三船舶及其结构 13.1 船舶结构基本知识 [3451] is the main center-line structural member,running fore and aft along the bottom of a ship,sometimes referred to as the backbone. A. Frame B. Deckbeam C. Stringer D. Keel KEY: D [3452]A band or collar on the top end of a ...

热门内容

0HAVC往事追忆_大学英语B级词汇表

   灿烂的语言,只能点缀感情,如果我沉默,代表我真的喜欢你 26、自由代表的是内心永久的孤独。 、自由代表的是内心永久的孤独。 27、现实太假,还是自己太傻? 、现实太假,还是自己太傻? 28、一切因为寂寞,才开始了暧昧。 、一切因为寂寞,才开始了暧昧。 29、生活的真正意义是:生下来,活下去。 、生活的真正意义是:生下来,活下去。 30、年龄不是差距,身高不是距离。 、年龄不是差距,身高不是距离。 31、人生是一张单程车票,没有后退,没有返回! 、人生是一张单程车票,没有后退,没有返回! 32 ...

【英语四级】新东方精英级作文辅导 范句+模板

   综合运用篇 Along with the advance of the society more and more problems are brought to our attention, one of which is that…. 随着社会的不断发展,出现了越来越多的问题,其中之一便是. As to whether it is a blessing or a curse, however, people take different attitudes. 然而,对于此类问题,人们持不 ...

新东方英语背诵美文30篇经典篇目!!!

   生而为赢     --新东方英语背诵美文30篇  目录: ?第一篇:Youth 青春 ?第二篇: Three Days to See(Excerpts)假如给我三天光明(节选) ?第三篇:Companionship of Books 以书为伴(节选) ?第四篇:If I Rest, I Rust 如果我休息,我就会生锈 ?第五篇:Ambition 抱负 ?第六篇:What I have Lived for 我为何而生 ?第七篇:When Love Beckons You 爱的召唤 ?第八篇: ...

新标准英语(三年级起点)第七册 第三模块小测题

   Module 3 Unit 1 & Unit 2 基础篇 六年级 ) 基础篇( 一、单词(每题 1 分,共 11 分) 1 收集2 邮票3 爱好4 那些5 从… 6 著名的7 男人(复数)8 女人(复数)9 一些 10 信11 另一个 二、词组(每题 2 分,共 13 分) 1 集邮2 有3 许多 种) (3 4 来自于(2 种)5 一封我的信 一、选择(每题 2 分,共 16 分) ( ) 1 Do you collect , Simon ? A stamp B stamps C ...

词汇发散记忆_史上最强的英语单词记忆法(101?200)全_【强烈推荐】

   到 全国最大家教 家教平台 找家教, 阳光 阳光家教网 全国最大家教平台 家教, 史上最强的英语单词记忆法(101?200)全 词汇发散记忆 史上最强的英语单词记忆法 ? 全 http://www.ygjj.com 家教网 找家教上阳光家教网 家教上 到 全国最大家教 家教平台 找家教, 阳光 阳光家教网 全国最大家教平台 家教, http://www.ygjj.com 家教网 找家教上阳光家教网 家教上 到 全国最大家教 家教平台 找家教, 阳光 阳光家教网 全国最大家教平台 家教, ht ...