数据采集系统DATAACQUISITIONSYSTEMS中英文对照

1、数据采集系统数据采集系统，正如名字所暗示的，是一种用来采集信息成文件或分析一些 现象的产品或过程。在最简单的形式中，技术人员将烤箱的温度记录在一张纸上 就是数据采集。随着技术的发展，通过电子设备，这个过程已经得到简化和变得 比较精确、多用途和可靠。设备从简单的存储器发展到复杂的电脑系统。数据采 集产品像聚焦点一样为系统服务，和一系列产品一起，诸如传感器显示温度、水 流、程度或者过程。数据采集技术在过去30到40年以来已经取得了很大的飞跃。举例来说，在 40年以前,在一个著名的学院实验室中，为追踪用青铜做的坩埚中的温度上升情 况的装置是由热电偶、继电器、查询台、一捆纸和一支铅笔。今天的大学学生很

2、可能在 PC机上自动处理和分析数据，有很多种可供你选 择的方法去采集数据。至于选择哪一种方法取决于多种因素，包括任务的复杂度、 你所需要的速度和精度、你想要的证据资料等等。无论是简单的还是复杂的，数 据采集系统都能够运行并发挥它的作用。用铅笔和纸的旧方式对于一些情形仍然是可行的，而且它便宜、易获得、快速和容易开始。而你所需要的就是捕捉到多路数字信息（DMM ），然后开始用手记录数据。不幸的是这种方法容易发生错误、采集数据变慢和需要太多的人工分析。 此 外，它只能单通道采集数据；但是当你使用多通道 DMM时，系统将很快变得非 常庞大和呆笨拙。精度取决于誊写器的水平，并且你可能需要自己动手依比例输

3、 入。举例来说，如果DMM没有配备处理温度的传感器，旧需要动手找比例。考 虑到这些限制，只有当你需要实行一个快速实验时，它才是一个可接受的方法。现代多种版本的长条图表记录仪允许你从多个输入取得数据。他们提供数据 的长备纸记录，因为数据是图解的格式，他们易于现场采集数据。一旦建立了长条 图表记录仪，在没有操作员或计算机的情况下，大多数记录仪具有足够的内部智 能运行。缺点是缺乏灵活性和相对的精度低， 时常限制在百分点。你能很清楚地 感觉到和笔只有小的改变。在多通道内较长时间的监控，记录仪能发挥很好的作 用，除此之外，它们的价值得到限制。举例来说，他们不能够和另外的装置轮流 作用。其他的顾虑就是笔和

4、纸的维护，纸的供给和数据的存储，最重要的是纸的滥 用和浪费。然而，记录仪相当容易建立和操作，为数据快速而简单的分析提供永 久的记录。一些benchtop DMMs提供可选择的扫描能力。仪器的背面有一个槽孔接 收一张在较多输入时能多重发讯的扫描仪卡片，通常是 8到10通道的mux。固有的在仪器的前面嵌板中的受到限制。 它的柔韧性也受到限制，因为它不能超过 可用通道数。外部的PC机通常处理数据采集和分析。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1000的阅读速率。8到16通道是普遍的，采集的 数据直接存储在电脑里，然后进行分析。因为卡片本质上

5、是计算机的一部分，建立测试是容易的。PC机卡也相对的便宜，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。数据采集的选择在缺点上，PC机插件卡片时常只有12字的容量，因此你不能察觉输入信号 的小变化。此外,PC机内的电子环境经常很容易发出噪声、 产生高速率的时钟和 总线噪声，电子接触面限制PC机插件卡片的精度。这些插件卡片也测量一定范 围的电压。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 信号监测的器件。其它关心包括复杂的校正和全部的系统成本，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，如果你的需 要在卡片的能力和限制范围内变动

6、，PC机插件卡片给数据采集提供吸引人的方 法。数据电子自动记录仪是典型的单机仪器，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和。它们能够处理多信号输入，有时可达 120通道。 精度可和无和伦比的台式 DMMs匹敌，由于它在22字、0.004个 百分率的精度范围内运转。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的限制，而且输出为控制作信号。使用数据电子自动记录仪的一个好处就是他们的内部监测信号。 大部分能够 直接地测量若干不同的输入信号，而不需要额外的信号监测器件。一个通道能够 监测热电偶、温阻器（RTD ）和电压。热电偶为准确的温度测量提供具有参考价值的

7、补偿，是很典型的配备了多路 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 道的参数。一旦你全部设定好，数据电子自动记录仪就如同无和伦比的装置运行。 它们存储的数据分布在内存中，能够容纳500000或更多的阅读量。和PC机连接容易将数据传送到电脑进行进一步的分析。大多数数据电子自动记录仪可设计为柔性和简单的组态和操作，而且经由电池包裹或其它方法，多 数提供远程位置的操作选项。靠 A/ D转换技术，一定的数据电子自动记录仪阅 读的速率比较低，尤其是跟PC机插件卡片比较。然而，每秒250的阅读速率比 较少见。要牢记正在测量的许多现象本质上是物理的，如温度、压力和流量，而且一

8、般有较少的变动。此外，因为数据电子自动记录仪的监测精度，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。前端数据采集经常做成模块而且是典型地和PC机或控制器连接。他们被用于自动化的测试中，为其它测试装备采集数据、控制和循环检测信号。发送信号 测试装备的零配件。前端运转的效率是非常高的，能和速度和精度和最好的单机 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Agile ntE1419A多功能测量和VXI控制模型，还有专有的卡片升降室。虽然前端器成 本已经降低,但是这些系统可能会非常贵，除非你需要提供高的运转，而查找它们 的价格是禁止的。另一方面，它们的确能够提供相当

9、多的可挠性和测量能力。好的、成本低的数据电子自动记录仪有合适的通道数（20-60通道）和扫描 速率相对低但对于多数工程师的普遍使用已足够。一些关键的使用包括：?产品特征?电子产品的热靠模切削?环境的测试环境的监测?组成物特征?电池测试建筑物和计算机容量监测DATA ACQUISITION SYSTEMSData acquisiti on systems, as the n ame implies, are products an d/or processes used to collect information to document or analyze some phenomenon.

10、In the simplest form, a technician logging the temperature of an oven on a piece of paper is perform ing data acquisiti on. As tech no logy has progressed, this type of process has been simplified and made more accurate, versatile, and reliable through electronic equipment. Equipment ranges from sim

11、ple recorders to sophisticated computer systems. Data acquisiti on products serve as a focal point in a system, tying together a wide variety of products, such as sensors that indicate temperature, flow, level, or pressure. Some com mon data acquisiti on terms are show n below.Data acquisiti on tech

12、 no logy has take n gia nt leaps forward over the last 30 to 40 years. For example, 40 years ago, in a typical college lab, apparatus for track ing the temperature rise in a crucible of sodium tun gste n- bronze con sisted of a thermocouple, a bridge, a lookup table, a pad of paper and a pen cil.Tod

13、ay' s coige stude nts are much more likely to use an automated process and an alyze the data on a PC Today, nu merous opti ons are available for gatheri ng data. The optimal choice depends on several factors, including the complexity of the task, the speed and accuracy you require, and the docum

14、entation you want. Data acquisition systems range from the simple to the complex, with a range of performa nee and fun ctio nality.The old pencil and paper approach is still viable for some situations, and it is inexpensive, readily available, quick and easy to get started. All you need to do is hoo

15、k up a digital multiple meters (DMM) and beg in record ing data by hand.Unfortunately, this method is error-prone, tends to be slow and requires extensive manual analysis. In addition, it works only for a single channel of data; while you can use multiple DMMs, the system will quickly becomes bulky

16、and awkward. Accuracy is depe ndent on the tran scribers level of fastidious ness and you may n eed to scale in put manu ally. For example, if the DMM is not set up to han dle temperature sensors, manual scaling will be required. Taking these limitations into account, this is often an acceptable met

17、hod when you need to perform a quick experime nt.Moder n versi ons of the ven erable strip chart recorder allow you to capture data from several in puts. They provide a perma nent paper record of the data, and because this data is in graphical format, they allow you to easily spot trends. Once set u

18、p, mostrecorders have sufficient internal intelligenee to run unattended without the aid of either an operator or a computer. Drawbacks in elude a lack of flexibility and relatively low accuracy, which is ofte n con stra ined to a few perce ntage poi nts. You can typically perceive only small cha ng

19、es in the pen plots. While recorders perform well when monitoring a few channels over a long period of time, their value can be limited. For example, they are un able to turn ano ther device on or off. Other concerns include pen and paper maintenance, paper supply and data storage, all of which tran

20、slate into paper overuse and waste. Still, recorders are fairly easy to set up and operate, and offer a permanent record of the data for quick and simple analysis.Some bench top DMMs offer an optional scanning capability. A slot in the rear of the in strume nt accepts a sca nner card that can multip

21、lex betwee n multiple in puts, with 8 to 10 cha nn els of mux being fairly com mon. DMM accuracy and the fun ctio nality in here nt in the in strume nts front panel are reta in ed. Flexibility is limited in that it is not possible to expa nd bey ond the nu mber of cha nn els available in the expa ns

22、ion slot. An exter nal PC usually han dles data acquisiti on and an alysis.PC plug-i n cards are sin gle-board measureme nt systems that take adva ntage of the ISA or PCI-bus expansion slots in a PC. They often have reading rates as high as 100,000 read ings per sec ond. Counts of 8 to 16 cha nn els

23、 are com mon, and acquired data is stored directly into the computer, where it can then be analyzed. Because the card is essentially part of the computer, it is easy to set up tests. PC cards also are relatively inexpensive, in part, because they rely on the host PC to provide power, the mecha ni ca

24、l en closure and the user in terface.In the downside, PC plug-in cards often have only 12 bits of resolution, so you can' perceive small variati ons with the in put sig nal. Furthermore, the electrical en vir onment in side a PC tends to be no isy, with high-speed clocks and bus no ise radiated

25、throughout. Often, this electrical interferenee limits the accuracy of the PC plug-in card to that of a handheld DMM .These cards also measure a fairly limited range of dc voltage. To measure other in put sig nals, such as ac voltage, temperature or resista nee, you may n eed some sort of external s

26、ig nal con diti oning. Additi onal concerns include problematic calibration and overall system cost, especially if you need to purchase additional signal conditioning accessories or a PC to accommodate the cards. Taking that into consideration, PC plug-in cards offer an attractive approach to data a

27、cquisiti on if your requireme nts fall with in the capabilities and limitati ons of the card.Data loggers are typically sta nd-al one in strume nts that, once they are setup, can measure, record and display data without operator or computer in terve ntio n. They can han dle multiple in puts, in some

28、 in sta nces up to 120 cha nn els. Accuracy rivals that found in standalone bench DMMs, with performanee in the 22-bit, 0.004-percent accuracy range. Some data loggers have the ability to scale measurements,check results against user-defined limits, and output signals for control.One advantage of us

29、ing data loggers is their built-in signal conditioning. Most are able to directly measure a nu mber of differe nt in puts without the n eed for additional signal conditioning accessories. One channel could be monitoring a thermocouple, ano ther a resistive temperature device (RTD) and still ano ther

30、 could be look ing at voltage.Thermocouple refere nee compe nsati on for accurate temperature measureme nt is typically built into the multiplexer cards. A data logger built-in in tellige nee helps you set up the test routine and specify the parametersof each channel. Once you have completed the set

31、up, data loggers can run as sta ndal one devices, much like a recorder. They store data locally in internal memory, which can accommodate 50,000 read ings or more.PC connectivity makes it easy to transfer data to your computer for in-depth analysis. Most data loggers are designed for flexibility and

32、 simple configuration and operation, and many provide the option of remote site operation via battery packs or other methods. Depe nding on the A/D conv erter tech nique used, certa in data loggers take readings at a relatively slow rate, especially compared to many PC plug-in cards. Still, read ing

33、 speedsof 250 read in gs/sec on dare not un com mon. Keep in mind that many of the phenomena being monitored are physical in nature such as temperature, pressure and flow and cha nge at a fairly slow rate. Additi on ally, because of a data logger superior measurement accuracy, multiple readings and averag ing are not n ecessary, as they ofte n are in PC plug-i n solutio ns.Data acquisiti on front ends are ofte n modular and are typically conn ected to a PC or controller. They are used in automated test applicat