ealackofflexibilityandrelativelylowaccuracy,whichisoftenconstrainedtoafewpercentagepoints.Youcantypicallyperceiveonlysmallchangesinthepenplots.Whilerecordersperformwellwhenmonitoringafewchannelsoveralongperiodoftime,theirvaluecanbelimited.Forexample,theyareunabletoturnanotherdeviceonoroff.Otherconcernsincludepenandpapermaintenance,papersupplyanddatastorage,allofwhichtranslateintopaperoveruseandwasetyofproducts,suchassensorsthatindicatetemperature,flow,level,orpressure.Somecommondataacquistiontermsareshownbelow:Dataacquisitiontechnologyhastakengiantleapsforwardoverthelasttoyears.Forexample,yearsago,inatypicalcollegelab,apparatusfortrackingthetemperatureriseinacrucibleofsodiumtungsten-bronzeconsistedofathermocouple,abridge,alookuptable,apadofpaperandapencil.Today'scollegestudentsaremuchmorelikelytouseanautomatedprocessandanalyzethedataonaPCToday,numerousoptionsareavailableforgatheringdata.Theoptimalchoicedependsonseveralfactors,includingthecomplexityofthetask,thespeedandaccuracyyourequire,andthedocumentationyouwant.Dataacquisitionsystemsrangefromthesimpletothecomplex,witharangeofperformanceandfunctionality.PencilandpaperTheoldpencilandpaperapproachisstillviableforsomesituations,anditisinexpensive,readilyavailable,quickandeasytogetstarted.Allyouneedtodoishookupadigitalmultimeter(DMM)andbeginrecordingdatabyhand.Unfortunately,thismethodiserror-prone,tendstobeslowandrequiresextensivemanualanalysis.Inaddition,itworksonlyforasinglechannelofdata;whileyoucanusemultipleDMMs,thesystemwillquicklybecomesbulkyandawkward.Accuracyisdependentonthetranscriber'sleveloffastidiousnessandyoumayneedtoscaleinputmanually.Forexample,iftheDMMisnotsetuptohandletemperaturesensors,manualscalingwillberequired.Takingtheselimitationsintoaccount,thisisoftenan高速数据采集系统acceptablemethodwhenyouneedtoperformaquickexperiment.StripchartrecorderModernversionsofthevenerablestripchartrecorderallowyoutocapturedatafromseveralinputs.Theyprovideapermanentpaperrecordofthedata,andbecausethisdataisingraphicalformat,theyallowyoutoeasilyspottrends.Oncesetup,mostrecordershavesufficientinternalintelligencetorununattended—withouttheaidofeitheranoperatororacomputer.Drawbacksincludealackofflexibilityandrelativelylowaccuracy,whichisoftenconstrainedtoafewpercentagepoints.Youcantypicallyperceiveonlysmallchangesinthepenplots.Whilerecordersperformwellwhenmonitoringafewchannelsoveralongperiodoftime,theirvaluecanbelimited.Forexample,theyareunabletoturnanotherdeviceonoroff.Otherconcernsincludepenandpapermaintenance,papersupplyanddatastorage,allofwhichtranslateintopaperoveruseandwas数据采集和分析。高速数据采集系统PC机插件卡片PC机插件卡片是单板测量系统,它利用ISA或PCI总线在PC机内扩大插槽。它们时常具有高达每秒阅读速率。到通道是普遍,采集数据直接存储在电脑里,然后进行分析。因为卡片本质上是计算机一部分,建立测试是容易。PC机卡也相对便宜,一部分地,因为他们以来主机PC去提供能源、机械附件和使用界面。数据采集选择在缺点上,PC机插件卡片时常只有字容量,因此你不能察觉输入信号小变化。此外,PC机内电子环境经常很容易发出噪声、产生高速率时钟和总线噪声,电子接触面限制PC机插件卡片精度。这些插件卡片也测量一定范围电压。为了测量其他输入信号,如电压、温度和阻力,你也许需要一些外部信号监测器件。其它关心包括复杂校正和全部系统成本,尤其如果你需要购买额外信号监测器件或用PC机适应插件卡片。把这些考虑进去,如果你需要在卡片能力和限制范围内变动,PC机插件卡片给数据采集提供吸引人方法。数据电子自动记录仪数据电子自动记录仪是典型单机仪器,一旦配备它们,就能测量、记录和显示数据而不需要操作员或计算机参与。它们能够处理多信号输入,有时可达通道。精度可与无与伦比台式DMMs匹敌,由于它在字、.个百分率精度范围内运转。一些数据电子自动记录仪有能力按比例测量,检查结果不受使用者定义限制,而且输出为控制作信号。使用数据电子自动记录仪一个好处就是他们内部监测信号。大部分能够直接地测量若干不同输入信号,而不需要额外信号监测器件。一个通道能够监测热电偶、温阻器(RTD)和电压。热电偶为准确温度测量提供具有参考价值补偿,是很典型配备了多路插件卡片。内设智能数据电子自动记录仪帮助你设定测量周期和具体指定每个通道参数。一旦你全部设定好,数据电子自动记录仪就如同无与伦比装置运行。它们存储数据分布在内存中,能够容纳或更多阅读量。高速数据采集系统与PC机连接容易将数据传送到电脑进行进一步分析。大多数数据电子自动记录仪可设计为柔性和简单组态和操作,而且经由电池包裹或其它方法,多数提供远程位置操作选项。靠A/D转换技术,一定数据电子自动记录仪阅读速率比较低,尤其是跟PC机插件卡片比较。然而,每秒阅读速率比较少见。要牢记正在测量许多现象本质上是物理,如温度、压力和流量,而且一般有较少变动。此外,因为数据电子自动记录仪监测精度,多量且平均阅读没有必要,就像它们经常在PC记插件卡片一样。前端数据采集前端数据采集经常做成模块而且是典型地与PC机或控制器连接。他们被用于自动化测试中,为其它测试装备采集数据、控制和循环检测信号。发送信号测试装备零配件。前端运转效率是非常高,能与速度和精度与最好单机仪器匹敌。前端数据采集在很多模型里都能运行,包括VXI版本,如AgilentEA多功能测量和VXI控制模型,还有专有卡片升降室。虽然前端器成本已经降低,但是这些系统可能会非常贵,除非你需要提供高运转,而查找它们价格是禁止。另一方面,它们确能够提供相当多可挠性和测量能力。数据电子自动记录仪应用好、成本低数据电子自动记录仪有合适通道数(-通道)和扫描速率相对低但对于多数工程师普遍应用已足够。一些关键应用包括:•产品特征•电子产品热靠模切削•环境测试;环境监测•组成物特征•电池测试•建筑物和计算机容量监测•过程监测,评估和故障修理没有哪一种数据采集系统能够适应所有情况。回答下列各问题,可能帮助你决定选哪一种数据采集系统最适合你实际情况:系统跟我应用匹配吗?测量方法、精度和噪声处理是什么?它扫描多快?什么传感器和支持什么测量功能?高速数据采集系统为了将来需要,它是可升级还是可扩张?它是便携式吗?它操作起来,是一个无与伦比仪器吗?它成本是多少?软件被包括在内,还是额外之物?它需要以信号数据片为条件吗?可靠周期是多少?它有多容易校正?它有多容易使用?规格能被了解吗?使用者界面如何?为新应用,再配置有多困难?数据能容易地被转移到新应用吗?支持哪一种应用包?结论数据采集能从铅笔,纸和一个测定装置发展到一个高度复杂系统硬件仪表和软件分析工具。使用者打算购买数据采集装置或系统第一步决定于身边任务和想要输出,然后选择类型和仪器符合他们标准范围。所有复杂设备和分析工具是帮助使用者理解检测对象。工具仅仅是对一个目一种方法。etyofproducts,suchassensorsthatindicatetemperature,flow,level,orpressure.Somecommondataacquistiontermsareshownbelow:Dataacquisitiontechnologyhastakengiantleapsforwardoverthelasttoyears.Forexample,yearsago,inatypicalcollegelab,apparatusfortrackingthetemperatureriseinacrucibleofsodiumtungsten-bronzeconsistedofathermocouple,abridge,alookuptable,apadofpaperandapencil.Today'scollegestudentsaremuchmorel高速数据采集系统SelectingtheRightDataAcquisitionSystemEngineersoftenmustmonitorahandfulofsignalsoverextendedperiodsoftime,andthengraphandanalyzetheresultingdata.Theneedtomonitor,recordandanalyzedataarisesinawiderangeofapplications,includingthedesign-verificationstageofproductdevelopment,environmentalchambermonitoring,componentinspection,benchtoptestingandprocesstrouble-shooting.Thisapplicationnotedescribesthevariousmethodsanddevicesyoucanusetoacquire,recordandanalyzedata,fromthesimplepen-and-papermethodtousingtoday'ssophisticateddataacquisitionsystems.Itdiscussestheadvantagesanddisadvantagesofeachmethodandprovidesalistofquestionsthatwillguideyouinselectingtheapproachthatbestsuitsyourneeds.IntroductionIngeotechnicalengineering,wesometimeencountersomedifficultiessuchasmonitoringinstrumentsdistributedinalargearea,dangerousenvironmentofworkingsitethatcausesomedifficultyforeasyaccess.Inthiscase,operatorsmayadoptremotecontrol,bywhichalargeamountofmeasureddatawillbetransmittedtoaobservationroomwherethedataaretobecollected,storedandprocessed.Theautomaticdataacquisitioncontrolsystemisabletocompletethetasksasregularautomaticdatamonitoring,acquisitionandstore,featuringhighautomation,largedatastorecapacityandreliableperformance.Thesystemiscomposedofacquisitioncontrolsystemanddisplaysystem,withthefollowingfeatures:.No.ofChannels:(canbeincreasedordecreasedaccordingtouser'srealneeds.).Scanningduration:decidedbyuser,fastestpoints/second.Storecapacity:G(maybeincreasedordecreased).Display:(a)Tableofparameter(b)Historytendency(c)Columngraphics..Function:realtimemonitoringcontrol,warning.Overalldimension:cmcmcm高速数据采集系统Dataacquisitionsystems,asthenameimplies,areproductsand/orprocessesusedtocollectinformationtodocumentoranalyzesomephenomenon.Inthesimplestform,atechnicianloggingthetemperatureofanovenonapieceofpaperisperformingdataacquisition.Astechnologyhasprogressed,thistypeofprocesshasbeensimplifiedandmademoreaccurate,versatile,andreliablethroughelectronicequipment.Equipmentrangesfromsimplerecorderstosophisticatedcomputersystems.Dataacquisitionproductsserveasafocalpointinasystem,tyingtogetherawidevarietyofproducts,suchassensorsthatindicatetemperature,flow,level,orpressure.Somecommondataacquistiontermsareshownbelow:Dataacquisitiontechnologyhastakengiantleapsforwardoverthelasttoyears.Forexample,yearsago,inatypicalcollegelab,apparatusfortrackingthetemperatureriseinacrucibleofsodiumtungsten-bronzeconsistedofathermocouple,abridge,alookuptable,apadofpaperandapencil.Today'scollegestudentsaremuchmorelikelytouseanautomatedprocessandanalyzethedataonaPCToday,numerousoptionsareavailableforgatheringdata.Theoptimalchoicedependsonseveralfactors,includingthecomplexityofthetask,thespeedandaccuracyyourequire,andthedocumentationyouwant.Dataacquisitionsystemsrangefromthesimpletothecomplex,witharangeofperformanceandfunctionality.PencilandpaperTheoldpencilandpaperapproachisstillviableforsomesituations,anditisinexpensive,readilyavailable,quickandeasytogetstarted.Allyouneedtodoishookupadigitalmultimeter(DMM)andbeginrecordingdatabyhand.Unfortunately,thismethodiserror-prone,tendstobeslowandrequiresextensivemanualanalysis.Inaddition,itworksonlyforasinglechannelofdata;whileyoucanusemultipleDMMs,thesystemwillquicklybecomesbulkyandawkward.Accuracyisdependentonthetranscriber'sleveloffastidiousnessandyoumayneedtoscaleinputmanually.Forexample,iftheDMMisnotsetuptohandletemperaturesensors,manualscalingwillberequired.Takingtheselimitationsintoaccount,thisisoftenan高速数据采集系统acceptablemethodwhenyouneedtoperformaquickexperiment.StripchartrecorderModernversionsofthevenerablestripchartrecorderallowyoutocapturedatafromseveralinputs.Theyprovideapermanentpaperrecordo 高速数据采集系统1SelectingtheRightDataAcquisitionSystemEngineersoftenmustmonitorahandfulofsignalsoverextendedperiodsoftime,andthengraphandanalyzetheresultingdata.Theneedtomonitor,recordandanalyzedataarisesinawiderangeofapplications,includingthedesign-verificationstageofproductdevelopment,environmentalchambermonitoring,componentinspection,benchtoptestingandpr