电气工程专业英语考试

♦While we appear to prefer the total objectivity of a mathematically formulated method of signal processing, it is now well proven that the AI methods often are better choices to use in terms of better speed of performance and often lower cost of processing.
♦当我们似乎更喜欢信号处理数学方法的整体客观性，现在证明，为了得到更好的速度性能和低成本的处理，人工智能方法经常是更好的选择。

♦Often they are the only solution since the algorithmic approach cannot be deployed because of the lack of a suitable mathematical formulation or powerful enough processor to run the algorithm.
♦经常当算法因为缺乏适合的数学表达式和足够强大处理器去运行算法而不能展开时，他们是唯一的解决方案。

♦Signal processing in the modern instrument, therefore, will often make use of many different methods. This account is an introduction to the characteristics of the various forms and is written to assist selection. Space limitations prevent presentation of each kind in detail.
因此，在现代仪器中的信号处理通常会使用许多不同的方法。

这个说明只是对各种形式特征的一个介绍并被书写出来以帮助选择。

空间的限制阻止了各种方法的详细介绍。

♦Traditionally the most popular method used to develop mapping models is that of mathematical modeling.
♦传统上用于开发映射模型中最受欢迎的方法是数学建模。

♦The mathematical model is usually what is sought, as it provides the highest level of understanding about the subject and the most precise representation of the behavior.
♦探索数学模型以提供课题最高水平理解和性能最精确的表达。

♦The major disadvantage of mathematical models is that they can quickly become so complex that implementation of these models in measurement systems is often impractical.
♦数学模型主要的缺点是迅速变得复杂，以致在测量系统中这些模型运行通常是不能实现的。

♦In this class, the single, or set of multiple, input signal(s) to the data processor is converted to the output form using tightly formulated mathematical description.
♦在这类，单一的或多个输入信号的数据处理通过密切使用数学描述转化为输出形式。

♦This relationship is called the algorithm. Strict relationships hold; the relationship is said to be formal, meaning that for any given input the output will always be the same. The algorithm supports only one interpretation.
♦这种关系被称为所谓的算法。

严格关系约束，关系可以说是有条理的，也就是说，对于任意给定输入输出将永远是一样的。

算法只提供一种诠释。

♦This method of signal processing is the most highly developed method and is certainly one to aim for because it is devoid of ambiguity.
♦信号处理的方法是最高速发展的方法，必然以毫无歧义为目标的。

♦All will agree on how it will respond. It carries a comforting level of understanding and, thus, acceptance.
♦所有方法对如何响应取得了一致意见。

它能达到一个令人欣慰的理解水平，从而接受它。

♦Algorithmic methods can be very accurate, traceable, and can be calibrated with relative ease and agreement.
计算方法可以是非常精确的，可描述的，并能较容易地调整并达成一致。

♦They are the basis of many instrumentation systems. The origin of their use in instrumentation goes back to the early days of computing using, first, mechanical computational machines (late 1800s to around 1930) and then analog electric devices (early 1900s to 1960s), all of which were mostly replaced by the use of digital computers commencing around 1950.
♦他们是许多仪器系统的基础。

在仪器中，他们使用的起源可追溯到的早期的计算机使用，首先，机械计算机器(19世纪后期到1930年)，然后到模拟电子设备(20世纪初到20世纪60年代)，所有这些都从大约1950年开始由于数字计算机的使用而被代替。

♦All of these algorithmic methods of processing can be simplistically regarded as embodiments of a mathematical
equation inside a suitable technological machine.
♦embodiments 体现；化身；具体化
♦mathematical equation 数学方程式
♦所有的这些处理方法可以简单地看成是一个包含适当的技术设备的数学方程具体化。

♦As the demands complexity and performance requirements grew over time, so the did the demands on the detail of the algorithm and the means to model it inside a computational machine.
♦随着时间过去，由于需求复杂性和性能要求的增长，所以在计算机器里对算法细节和模型方法有要求。

♦Mathematical description eventually reaches limits of definition as the models push the boundaries of mathematical methods and human development. Too often, this arises before adequate detail is able to be built into the model. The algorithm is then an inadequate model of the need.
♦当模型推动数学描述方法和人类发展的界限，数学描述最终到达定义极限。

通常，适当的细节能够被构造进模型之前产生。

算法是由于模型不足而产生的需要
♦As the algorithm increases in complexity, the processing power needed must be increased to maintain both fidelity and speed of processing.
♦随着算法复杂度的增长，处理能力必须提高以保持精确和处理速度。

♦Despite great advances being made in algorithm development and in computer power, the algorithmic methodology eventually encountered mathematical and technological barriers in many fields.
♦尽管在算法的发展和计算能力上得到进步，在许多领域算法的方法论最终遇到数学上和技术上的壁垒♦The method is seen to not always be the best to use because of lack of an adequate algorithm or the high cost of computing.
♦研究方法因为缺乏适当的算法或由于高成本的计算不能得到最好地使用。

♦In instrumentation, another factor also arises. Fast, detailed processing brings with it the need for increasing electrical bandwidth requirements in signal transmission. This increases implementation costs and also eventually reaches technological constraints.
♦在仪器上，另外一个因素也出现。

在信号传输上快速的具体处理导致需要增加电气带宽要求。

增加的施工成本也最终达到技术限制。

♦Fortunately the solutions that may overcome these limiting constraints in many circumstances were developing in other fields under the general name of artificial intelligence (now called applied intelligence in engineering), as new forms of mathematics and in other fields, such as decision theory.
♦幸运的是在很多情况下可以克服这些约束限制的解决方案在人工智能的其他领域中发展(现在称为“工程上的人工智能)，作为数学和其他领域的新形式，如决策论。

♦Principally, a key limitation of the algorithmic method is that its unforgiving level of formalism carries with it a depth of processing exactitude that is often not warranted.
♦主要来说，一个算法的关键的局限性是它形式主义过于苛刻的水平极大地影响了它处理精度的深度。

♦Other methods have emerged that allow vaguely subjective, as opposed to tightly objective, processing to be applied to good effect.
♦其他方法表现出允许含糊的主观，而不是严谨的客观，应用效果良好。

♦There AI methods have gradually gained acceptance to the degree that many are now routinely used and are supported by dedicated applications software and electronic integrated circuitry.
♦人工智能方法在一定程度上逐渐获得接受，以至于现在许多被日常使用，并受专门应用软件和电子集成电路支持。

♦At first, these many alternatives were seen to be isolated methods. Gradually, the literature has shown trends to merge them in pairs.
♦首先，许多选择被看做是独立的方法。

渐渐地，文献显示出成双融合的趋势。

♦Their use in a more widely mixed form is still limited. This account seeks to give a comprehensive appreciation of the commonly met AI processing methods by placing them into relative perspective.
♦在一个更广泛的混合形式中使用仍然受到限制。

通过把他们放在一个相对的角度上，这个说明试图给出一些常见的人工智能的处理方法的综合评价
♦It is interesting to contemplate that natural world computing in animals does not appear to make much use of algorithmic methods, but does make extensive use of the methods presented here in the AI class.
♦令人感兴趣的是认为在动物实验中自然界计算似乎不会大量使用的算法，但这里提供了在人工智能中广泛使用的算法。

♦The paradigm invoked here is that experience has shown that informal methods based on knowledge-based systems (KBS) can produce mappings of many inputs to one by use of less than completely formal description.
♦这里是调用的范例展示了这样的经验，基于知识系统(KBS)的一些常用方法可以通过使用不完整的形式描述产生多种输入到一个输出映射。

♦The AI methods can yield surprisingly efficient solutions to previously unsolved needs. They often can outperform algorithmic methods or carry out a similar task with far less computing power.
♦人工智能方法能提供惊人的有效方案去解决以前未解决的需求。

他们往往比计算方法好或是用更少的计算能力就可执行类似任务。

♦They are all associated with multiple input processing and can be applied to forming decisions from data supplied by sensors. Each situation has to be judged on the balance between use of computing effort and effective processing.
♦他们与多重输入处理有关并应用于将通过传感器提供的数据形成决策。

每个情况通过平衡计算量的使用和有效的处理进行判断。

♦On the downside, they lack formality and thus may be very hard to calibrate and authenticate. They, not having adequate scientific foundati on and a solid formal base of operation, are not easily accepted as “sound”.
♦不利的一面是他们缺乏形式，因此可能很难进行调整和验证。

他们没有充足的科学基础和坚实的正式运行基础，不能轻易地认为是“可靠的”而被接受。

♦They are often hard to comprehend by a second party, for their description is not always adequately documented or done to any agreed convention. As their principles vary widely, they must be well understood before application is developed.
♦他们往往很难被另一流派理解，因为他们的描述并没有充分的文件可证明或做任何约定公约所规定。

随着他们的原理广泛改变，他们必须在广泛应用之前被深入了解。

♦For all of these negative factors, they often are able to provide “more performance for less cost” and thus will be increasingly adopted.
♦对于所有这些不利因素,他们往往能提供“更多的性能以得到低成本”，从而越来越多地采用。

♦Their rising level of use should not suggest the algorithmic methods will become obsolete, but more that the instrument designer now has a much larger set of processing tools available.
♦使用的持续升级并不表明算法成为过时，但现在仪器设计者有更多的可用处理工具。

Unit 12 Simple Instrument Model
简易的仪器模型
♦In addressing measurement problems, it is often useful to have a conceptual model of the measurement process. This unit presents some of the fundamental concepts of measurement in the context of a simple generalized in strument model. 在解决测量问题的过程中，一个测量过程的概念模型常常是很有用的。

在测量仪器模型简单概括的情况下，本单元介绍一些测量的基本概念。

♦Fig.12.1 presents a generalized model of a simple instrument. The physical process to be measured is in the left of the figure and the measurand is represented by an observable physical variable X.
♦Fig.12.1提出了一种简易仪器的概念模型。

物理过程在左边的图形中进行测量，被测变量以一种可观测的物理变量X描述。

♦Note that the observable variable X need not necessarily be the measurand but simple related to the measurand in some known way.
♦需注意的是，观测变量X不需要一定是个被测变量，而是在一些已知的方法中简简与被测变量相关。

♦For example, the mass of an object is often measured by the process of weighing, where the measurand is the mass but the physical measurement variable is the downward force the mass exerts in the Earth’s gravitational field. There are many possible physical measurement variables. A few are shown in Table 12.1.
♦例如，物体的质量通常是通过称重来测量，被测变量是物体但是实际测量变量却是地球引力场作用于物体的向下的引力。

一些可以在表12.1中看出。

♦The key functional element of the instrument model shown in Fig.12.1 is the sensor, which has the function of converting the physical variable input into a signal variable output.
♦在图.12.1中仪器模型的核心功能部件是传感器，它的功能是将物理变量输入转换成信号变量输出。

♦Signal variable have the property that they can be manipulated in a transmission system, such as an electrical or mechanical circuit. 在传输系统中信号变量具有可操作的特性，如电子回路或机械电路。

♦Because of this property, the signal variable can be transmitted to an output or recording device that can be remote from the sensor. 因为这个特性，信号变量可以被传送到一个远离传感器的输出或记录装置。

In electrical circuits, voltage is a common signal variable. In mechanical systems, displacement or force are commonly used as signal variables. 在电路中，电压是一种常见的可变信号。

在机械系统、位移和力通常被用做信号变量
♦Other examples of signal variable are shown in Table 12.1. The signal output from the sensor can be displayed, recorded, or used as an input signal to some secondary device or system. 信号变量的其他例子展现在表12.1。

从传感器输出的信号能够被显示、记录或者被用作为一个输入信号传输到一些次要设备或系统。

In a basic instrument, the signal is transmitted to a display or recording device where the measurement can be read by a human observer.在一个基本仪器中，信号被传送到一个显示或记录设备中以便可以被观测者读出。

♦The observed output is the measurement M. There are many types of display devices, ranging from simple scales and dial gages to sophisticated computer display systems.
♦观察结果是M。

有很多类型的显示设备，从简单的天平和各类千分尺到复杂的电脑显示器。

♦The signal can also be used directly by some larger system of which the instrument is a part. For example, the output signal of the sensor may be used as the input signal of a closed loop control system.
这个信号也可以通过一些较大的系统的仪器零件直接使用。

例如，传感器的输出信号可作为闭环控制系统的输入信号。

♦If the signal output from the sensor is small, it is sometimes necessary to amplify the output shown in Fig.12.2.
♦如果从传感器输出的信号是小的，在Fig.12.2中放大输出量有时是必要的。

♦The amplified output can then be transmitted to the display device or recorded, depending on the particular measurement application. 然后放大输出可以传送给显示器或根据特定的测试程序记录。

♦In many cases it is necessary for the instrument to provide a digital signal output so that it can interface with a computer-based data acquisition or communications system. 在很多情况下，仪器提供一个数字信号输出是很有必要的，这样它就可以与一个以计算机为基础的数据采集和通讯系统连接。

♦If the sensor does not inherently provide a digital output, then the analog output of the sensor is converted by an analog to digital converter (ADC) as shown in Fig.12.2. 如果传感器本身不能提供一个数字输出，那么传感器模拟输出将由一个模拟/数字转换器(ADC)转换，如图12.2所示
♦The digital signal is typically sent to a computer processor that can display, store, or transmit the data as output to some other system, which will use the measurement.
♦数字信号通常发送给计算机处理器，以便可以显示、存储或传输数据作为其他系统输出，并可以使用测量值。

♦The null method is one possible mode of operation for a measuring instrument. A null instrument uses the null method for measurement.
♦对于测量仪器零点法是一种合理的运作模式。

零点调整仪采用零点法作为测量方法。

♦In this method, the instrument exerts an influence on the measured system so as to opposite in value, yielding a null measurement.
♦在该方法中，仪器对测量系统产生了影响以便与值相反，创造出一个无效的测量。

♦Typically, this is accomplished by some type of feedback operation that allows the comparison of the measurand against a known standard value.
♦通常，由某种类型的反馈操作运行，这种类型的反馈操作允许被测变量与已知标准值进行比较。

♦Key features of a null instrument include: an iterative balancing operation using some type of comparator, either a manual or automatic feedback used to achieve balance, and a null deflection at parity shown in Fig.12.3.
♦零点调整仪的主要特点包括：使用某种比测仪的重复平衡操作，手动或是自动的反馈用以实现平衡，和零偏斜。

在图12.3中同等显示。

♦ A null instrument offers certain intrinsic advantages over other modes of operation (e.g., see deflection instruments).
♦在零点调整仪中提供一定的内在优点优于其他操作方式(例如，偏摆仪器)。

♦By balancing the unknown input against a know standard input, the null method minimizes interaction between the measuring system and the measurand.
♦通过平衡未知输入和一个已知的标准的输入，零点法将测量系统和被测变量之间的相互作用减到最小。

♦As each input comes from a separate source, the significance of any measuring influence on measurand by the measurement process in reduced.
♦因为每个输入来自一个独立的来源，任何测量的重要性通过测量过程降低对被测变量的影响。

♦In effect, the measured system sees a very high input impedance, thereby minimizing loading errors.
♦实际上，测量系统看成一个非常高的的输入阻抗，从而减少负载误差。

♦This is particularly effective when the measurand is a very small value. Hence, the null operation can achieve a high loading error.
♦当被测变量是一种非常小的值时这是非常有效的。

因此，零操作可达到高负载误差。

♦In practice, the null instrument will not achieve perfect parity due to the usable resolution of the balance and detection methods, but this is limited only by the state of the art of the circuit or scheme being employed [shown in Fig.12.4].
♦实际上，零点调整仪由于平衡和检测方法的有效的分辨率不能达到完全的相等，但这仅限制于电路目前的工艺水平或使用的方案[图12.4所示]。

♦ A disadvantage of null instruments is that an iterative balancing operation requires more time to execute than simply measuring sensor input. Thus, this method might not offer the fastest measurement possible when high-speed of measurements are required.
♦零点调整仪的缺点是与简单的测量传感器输入相比迭代平衡操作需要更多时间去执行。

因此，当要求快速测量时该方法不可能提供最快的测量。

♦However, the user should weigh achievable accuracy against needed speed of measurement when considering operational modes. Further, the generally not the lowest cost measuring alternative.
♦然而，当考虑到运作模式时，用户在测量精度和所需要的测量速度中进行权衡，进一步说，一般不以最
低成本测量所选择。

♦The deflection method is one possible mode of operation for a measuring instrument. A deflection instrument uses the deflection method for measurement.
♦偏转法是测量仪器的一种合理的运行模式。

偏转量仪器是使用偏转法进行测量。

A deflection instrument is influenced by the measurand so as to bring about a proportional response within the instrument.
♦偏转量仪器被被测变量影响以致于在仪器中导致相称的响应。

♦This response is an output reading that is a deflection or a deviation from the initial condition of the instrument.
♦这种响应是一个输出，读出的是从仪器的初始条件下的偏差或误差。

♦In a typical form, the measurand acts directly on a prime element or primary circuit so as to convert its information into a detectable form.
♦在一个典型的形式中，被测变量直接对主要因素或者初级回路起作用以便将信息转换成一个可检测的形式。

♦The name is derived from a common form of instrument where is a physical deflection of a prime element that is linked to an output scale, such as a pointer or other type of readout, which deflects to indicate the measured value.
♦这个名字源自一个常见的仪器，在主要元素物理偏差被连接到一个输出，如一个指针或其他类型的读数，转向显示测量值。

♦The magnitude of the deflection of the prime element brings about a deflection in the output scale that is designed to be proportional in magnitude to the value of the measurand.
♦在输出的测量中，主要元素的偏差大小产生偏差，被设计成与被测变量值的大小成比例。

♦Deflection instruments are the most common of measuring instruments.
♦偏差仪器是最常见的是测量仪器。

♦The relationship between the measurand and the prime element or measuring circuit can be a direct one, with no balancing mechanism or comparator circuits used.
♦被测变量和主要因素的关系或是测量电路可能是直接的，不需要平衡机制或是使用的比较仪电路。

♦The proportional response can be manipulated through signal conditioning methods between the prime element and the output scale so that the output reading is a direct indication of the measurand.
♦通过在主要元素和输出比例之间的信号调节方法，这个比例的响应能够被人工操作，以致输出是被测变量的直接指示。

♦Effective designs can achieve a high accuracy, yet sufficient accuracy for less demanding uses can be achieved at moderate costs.
♦有效的设计可以达到高精度，但在适当的成本下对于低要求的使用能够达到适当的精度。

♦An attractive feature of the deflection instrument is that it can be designed for either static or dynamic measurements or both. 偏差仪器的一个显著的特征是它可以设计为静态或动态测量或两者兼而有之。

♦An Advantage to deflection design for dynamic measurements is in the high dynamic response that can be achieved.
♦动态测量的偏差设计的优点是在高动态响应下可以实现。

♦ A disadvantage of deflection instruments is that by deriving its energy from the measurand, the act of measurement will influence the measurand and change the value of the variable being measured.
♦偏差仪器的缺点是要从被测变量中获得他的能量，其测量的方式影响被测变量并且改变被测量变量值。

♦This change is called a loading error. Hence, the user must ensure that the resulting error is acceptable. This usually involves a careful look at the instrument input impedance for the intended measurement.
♦这种变化是称为负载误差。

因此，用户必须确保所产生的误差是可以接受的。

为了预期的测量，通常涉及到仪器输入阻抗的认真考虑。

Computer-integrated manufacturing (CIM) is a philosophy for integrating hardware and software in such a way as to achieve total automation.
Computer-integrated manufacturing (CIM)
计算机集成制造
philosophy：哲学，哲理，理念；
计算机集成制造(CIM)是通过软硬件集成实现整体自动化的一种理念。

Although each company has its own idea of what CIM really means, most follow a pattern similar to that in Fig.8.1.
尽管不同的公司对CIM的含义有自己的理解，但大多数认同类似于图8.1的模型。

In this diagram, dedicated processing tasks are shown distributed around a factory.
该图中给出了工厂中分布式的特定任务处理过程。

As computers are further removed form the actual manufacturing area, their function shifts from real-time control toward supervision.
real-time control 实时控制
supervision 监督，管理
由于计算机与实际加工制造区域有相当的距离，故其功能由实时控制变为监控。

It is generally agreed that at least three levels of computer integration are required for CIM to work: the cell level, the area level, and the plant level.
the cell level:单元级the area level：装置级
the plant level ：厂级
通常认为CIM至少需要实现3级计算机集成，即单元级、装置级和厂级。

Each level has certain tasks within its range of responsibility.
每一级在其职责范围内都具有明确的任务。

Cell controllers, for example, are generally responsible for data acquisition and direct machine control.
Cell controllers:单元控制器data acquisition: 数据获取
例如单元控制器通常实现数据获取和直接机器设备控制。

Area controllers are assigned the tasks of machine and tool management, maintenance tracking, material handling and tracking, and computer-assisted simulation and design facilities.
computer-assisted simulation:计算机仿真
区域控制器被分配以机器和工具的管理、跟踪维护、原材料处理和跟踪，以及计算机仿真和设计设备等任务。

The plant-level computers are responsible for such things as purchasing, accounting, materials management, resource planning and report generation.
厂级计算机管理负责诸如采购、记账、原材料管理、资源规划和报表生成等任务。

When you develop a CIM system, it is best to start at the lowest level. Refer to Fig.8.1.
CIM系统的设计最好从最低层开始(见图8.1)。

Begin by completely developing the control for one cell. Then do the next cell, and so on. Then develop the area controllers.
最初完成某区域一个单元的控制，随后是下—个单元，依次类推，然后实现区域控制器。

Only when the cell controllers function properly should you develop the plant controller.
只有在单元控制器功能完备的情况下，才能开发区域控制器。

If CIM system fail, they do so for two major reasons. First, the design of the system is started at the top with the plant controller and works its way down. This does not work－it is backward.
导致CIM系统失败的原因通常有两个，第一个是始于顶端的自上而下的工厂控制器设计，这种反向设计的系统将无法工作。

A second reason for the systems failure to come on line properly is using different machines made by various manufactures.
系统设计失败的第二个原因是在具有完整生产线的情况下，采用了不同制造商的设备。

For example, we have 17 individual cell devices in four different cells. Your company procures 17 machines and 5 computers to be used as cell controllers.
例如在4个不同的单元中有17个独立的单元设备。

若某公司采购了17台设备和5台用于单元控制器的计算机。

When connected, the machines and computers do not “talk”to each other, and nothing work together.
但在进行连接时会发现计算机和机器之间无法通信，不能共同工作。

When you call the computer manufacturer and the 17 cell device manufacturers, you find out no one is responsible for the communication between devices.
此时若与计算机制造商和17个单元设备制造商联系，会发现没有一家对设备之间的通信负责。

Each manufacturer is only responsible for the programs of its own devices.
每一厂商仅对自己设备的程序负责。

In a CIM project, it is necessary to ascertain communication ability between devices before buying any device.
在CIM项目中，必须在采购任何设备之前确定设备之间的通信能力。

One organization or person should write or procure the overall networking programs for the CIM cell early in the project time frame.
组织或个人在项目计划的早期写出或获取整个CIM单元的网络程序。

Technically speaking, any computer, including the PLC, is capable of performing both control and supervisory tasks.
就技术而言，包括PLC在内的任何计算机都具有完成控制和监控任务的能力。

The trend, however, is toward customizing computers for specific applications. These customized controllers are called plant controllers.
但总的趋势是在特定的应用中采用定制计算机。

这些定制控制器称为工厂控制器。

It can be seen from the hierarchical structure of CIM that specialized computers would be advantageous.
hierarchical structure: 阶梯结构，分层结构
specialized computers:定制计算机
从CIM的阶梯结构可以看出定制计算机的优点。

In fact, many companies are already producing computers to satisfy the specific requirements of every facilities.
实际上，许多公司已经生产了满足不同设施特殊要求的计算机。

In some cases, those computers were already in place to handle such tasks as inventory and payroll.
某些情况下，这些计算机已用于处理诸如库存管理和工资发放等任务。

To promote them to the top of the CIM pyramid, one simply selects the proper software.
为将它提升到CIM金字塔的顶端，一个简单的方法就是选择合适的软件。

These computers are usually in a location remote from the actual plant floor. All the information they require is available from the host of subordinate area controllers throughout the plant.
这些计算机通常远离厂房，所需的信息来自分布于厂区内的各个下级区域控制器。

Area controllers are usually on the plant floor and therefore subjected to a harsh environment.
subjected to：遭受，承受
区域控制器通常位于厂区，故必须能够适应恶劣环境。

A special breed of computers, called industrial computers, has been developed specifically for this application.
breed:种类，类型
针对这种环境开发的特种计算机称为工业计算机。

The main difference between a PC and an industrial computer lies in the physical construction.
PC和工业计算机的区别在于物理结构。

Very simply, industrial computers are built to withstand higher temperatures, greater vibration, electromagnetically noisy environments, and rough handling.
简而言之，工业计算机必须能承受高温、剧烈振动、电磁噪声环境和野蛮操作。

Since their task is still supervisory in nature, their operating hardware does not differ significantly from that of a PC.
由于其任务本质上依然是监控，故其工作硬件与PC无明显区别。

Again, it is the software that turns a generic computer into an industrial computer.
但软件使其从通用计算机变成了工业计算机。

The PC should not be ruled out as a strong contender for the position of area controller.
PC作为区域控制器的强大竞争者的角色是显而易见的。

Personal computers are inexpensive, and with the myriad clones available, they are plentiful. An added advantage of using PCs for area control is that there is a large software base already established for such computers.
PC成本低廉并具有大量兼容产品。

选用PC作为区域控制器的另一优点是这种计算机具有广泛的软件基础。

The most specialized computers are cell controllers, those used to control work cells.
单元控制器是最专用的计算机，常用于实现工作单元控制。

A cell is defined as a group of machine tools or equipment integrated to perform a unit of the manufacturing process.
单元即为完成一个制造过程而集成的一组机床或设备。

Therefore, the computer that coordinates action within the cell has special hardware requirements as well as special software requirements.
因此,单元内计算机协调行动不仅有特殊的硬件要求而且有特殊的软件需求。

Specifically such a computer must have multiple data paths(I/O ports) through which it may communicate with the various cell devices.
特别是这样一个计算机必须具有多数据通道(I/O)，以实现与不同单元设备的通信。

Traditionally, cell control has been accomplished with PLCs, which were designed for this very purpose.
通常，单元控制可采用PLC完成，其设计常适合于该目的。

A CIM structure, however, requires that the cell coordinators communicate with other cell controllers, as well as with the area controller. The language of the PLC is somewhat restricting in this respect.
但CIM的结构要求单元协调器同时实现与其他单元控制器和区域控制器的通信，PLC在该方面有些欠缺。

In addition, most PLC languages do not lend themselves well to analysis and record keeping tasks.。