外文翻译可编程逻辑操纵器

附录二 外文文献及其翻译

Programmable logic controller

Cynthia cooper

From Wikipedia, the free encyclopedia

A programmable logic controller or simply programmable

controller is a digital computer used for of industrial processes, such

as control of machinery on factory . Unlike general-purpose

computers, the PLC is designed for multiple inputs and output

arrangements, extended temperature ranges, immunity to electrical

noise, and resistance to vibration and impact. Programs to control

machine operation are typically stored in battery-backed or

memory. A PLC is an example of a system since output results must

be produced in response to input conditions within a bounded time,

otherwise unintended operation will result.

Features

Control panel with PLC (grey elements in the center). The unit

consists of separate elements, from left to right; , controller, units

for input and output.

The main difference from other computers is that PLCs are

armored for severe condition (dust, moisture, heat, cold, etc) and

have the facility for extensive (I/O) arrangements. These connect the

PLC to and . PLCs read limit , analog process variables (such as

temperature and pressure), and the positions of complex positioning

systems. Some even use . On the actuator side, PLCs operate , or

cylinders, magnetic or , or analog outputs. The input/output

arrangements may be built into a simple PLC, or the PLC may have

external I/O modules attached to a computer network that plugs into

the PLC.

PLCs were invented as replacements for automated systems that

would use hundreds or thousands of , , and . Often, a single PLC can

be programmed to replace thousands of . Programmable controllers

were initially adopted by the automotive manufacturing industry,

where software revision replaced the re-wiring of hard-wired control

panels when production models changed.

Many of the earliest PLCs expressed all decision making logic in

simple which appeared similar to electrical schematic diagrams. The

electricians were quite able to trace out circuit problems with

schematic diagrams using ladder logic. This program notation was

chosen to reduce training demands for the existing technicians. Other

early PLCs used a form of programming, based on a stack-based

logic solver.

The functionality of the PLC has evolved over the years to include

sequential relay control, motion control, , and . The data handling,

storage, processing power and communication capabilities of some

modern PLCs are approximately equivalent to . PLC-like

programming combined with remote I/O hardware, allow a

general-purpose desktop computer to overlap some PLCs in certain

applications.

Under the standard, PLCs can be programmed using

standards-based programming languages. A graphical programming

notation called is available on certain programmable controllers.

PLC compared with other control systems

PLCs are well-adapted to a range of tasks. These are typically

industrial processes in manufacturing where the cost of developing

and maintaining the automation system is high relative to the total

cost of the contain input and output devices compatible with

industrial pilot devices and applications are typically highly

customized systems so the cost of a packaged PLC is low compared

to the cost of a specific custom-built controller design. On the other

hand, in the case of mass-produced goods, customized control

systems are economic due to the lower cost of the components,

which can be optimally chosen instead of a "generic" solution。

For high volume or very simple fixed automation tasks, different

techniques are used. For example, a consumer would be controlled

by an electromechanical costing only a few dollars in production

quantities.

A -based design would be appropriate where hundreds or

thousands of units will be produced and so the development cost

(design of power supplies and input/output hardware) can be spread

over many sales, and where the end-user would not need to alter the

control. Automotive applications are an example; millions of units are

built each year, and very few end-users alter the programming of

these controllers. However, some specialty vehicles such as transit

busses economically use PLCs instead of custom-designed controls,

because the volumes are low and the development cost would be

uneconomic.

Very complex process control, such as used in the chemical

industry, may require algorithms and performance beyond the

capability of even high-performance PLCs. Very high-speed or

precision controls may also require customized solutions; for

example, aircraft flight controls.

PLCs may include logic for single-variable feedback analog

control loop, a "proportional, integral, derivative" or "." A PID loop

could be used to control the temperature of a manufacturing process,

for example. Historically PLCs were usually configured with only a few

analog control loops; where processes required hundreds or

thousands of loops, a (DCS) would instead be used. However, as

PLCs have become more powerful, the boundary between DCS and

PLC applications has become less clear-cut.

Digital and analog signals

Digital or discrete signals behave as binary switches, yielding

simply an On or Off signal (1 or 0, True or False, respectively). Push

buttons, limit switches, and are examples of devices providing a

discrete signal. Discrete signals are sent using either or , where a

specific range is designated as On and another as Off. For example, a

PLC might use 24 V DC I/O, with values above 22 V DC representing

On, values below 2VDC representing Off, and intermediate values

undefined. Initially, PLCs had only discrete I/O.

Analog signals are like volume controls, with a range of values

between zero and full-scale. These are typically interpreted as integer

values (counts) by the PLC, with various ranges of accuracy

depending on the device and the number of bits available to store

the data. As PLCs typically use 16-bit signed binary processors, the

integer values are limited between -32,768 and +32,767. Pressure,

temperature, flow, and weight are often represented by analog

signals. Analog signals can use or with a magnitude proportional

to the value of the process signal. For example, an analog or 0 -

10 V input would be into an integer value of 0 - 32767.

Programming

Early PLCs, up to the mid-1980s, were programmed using

proprietary programming panels or special-purpose programming .

they were designed to replace relay logic systems. These PLCs were

programmed in "", which strongly resembles a schematic diagram of

relay logic. Modern PLCs can be programmed in a variety of ways,

from ladder logic to more traditional programming languages such

as BASIC and C. Another method is , a designed to program PLCs

based on .

Recently, the International standard has become popular. IEC

61131-3 currently defines five programming languages for

programmable control systems: FBD (), LD (), ST (, similar to the ), IL (,

similar to ) and SFC (). These techniques emphasize logical

organization of operations.

While the fundamental concepts of PLC programming are

common to all manufacturers, differences in I/O addressing, memory

organization and instruction sets mean that PLC programs are never

perfectly interchangeable between different makers. Even within the

same product line of a single manufacturer, different models may not

be directly compatible.

User interface

PLCs may need to interact with people for the purpose of

configuration, alarm reporting or everyday control. A (HMI) is

employed for this purpose. HMI's are also referred to as MMI's (Man

Machine Interface) and GUI (Graphical User Interface).

A simple system may use buttons and lights to interact with the

user. Text displays are available as well as graphical touch screens.

Most modern PLCs can communicate over a network to some other

system, such as a computer running a (Supervisory Control And

Data Acquisition) system or web browser.

Communications

PLCs usually have built in communications ports usually 9-Pin ,

and optionally for and . or is usually included as one of the .

Others' options include various such as or .

History

The PLC was invented in response to the needs of the American

automotive industry. Before the PLC, control, sequencing, and safety

interlock logic for manufacturing automobiles was accomplished

using relays, timers and dedicated closed-loop controllers. The

process for updating such facilities for the yearly model change-over

was very time consuming and expensive, as the relay systems needed

to be rewired by skilled electricians. In 1968 GM Hydramatic (the

automatic transmission division of General Motors) issued a request

for proposal for an electronic replacement for hard-wired relay

systems.

The winning proposal came from Bedford Associates of . The first

PLC, designated the 084 because it was Bedford Associates'

eighty-fourth project, was the result. Bedford Associates started a

new company dedicated to developing, manufacturing, selling, and

servicing this new product: Modicon, which stood for MOdular DIgital

CONtroller. One of the people who worked on that project was , who

is considered to be the "father" of the PLC. The Modicon brand was

sold in 1977 to , and later acquired by German Company and then

by French , the current owner.

The automotive industry is still one of the largest users of

PLCs, and Modicon still numbers some of its controller models.

PLCs are used in many different industries and machines such as

packaging and semiconductor machines. Well known PLC brands

are , , , , , , and .

中文译文：

可编程逻辑操纵器

辛西娅.库珀

维基自由百科全书

可编程逻辑操纵器或简易可编程操纵器是一种数字化的运算机，它应用于工业自动化的生产进程中，比如工厂装配生产线中机械的操纵。不同于一般用途的运算机，可编程逻辑操纵器是专为安排多输入和多输出而设计的，它拓展了工作温度范围，可抑制电气噪声，抗振动和干扰。程序操纵机械操作指令通常存储在备用电池或非易失性存储器中。PLC要求实时系统的输出结果在一个时刻范围内必需对输入条件做出响应，不然会致使误操作。

特点

PLC的操纵面板（灰色元素的中心），它的每一个单位都是由单独的元素组成的，由左向右别离是：电源供给器，操纵器，继电器单元的输入输出。

PLC和其他运算机的要紧区别是它适用于各类恶劣环境条件（如尘埃，潮湿，高温，低温等），并配备了适合于各类输入/输出端口的设备。 这些设备将PLC连接到相应的传感器和信号发生器上。PLC能够概念各类开关量，模拟量（如温度和压力等）用来配置各类复杂系统的各类变量，一些PLC乃至还需要利用机械视觉。在信号发生器方面，PLC能够操纵的设备有电动机，气压缸或液压缸，电磁继电器或螺线管继电器，和一些模拟输出设备。通过输入/输出模块的配置，能够构建一个简单的PLC系统。那个PLC系统能够通过外部I/O模块连接到一个运算机网络上。

PLC的显现改变了过去利用成百上千的继电器、凸轮按时器、鼓音序器来构建一个自动化系统的时期。通常，一个简单可编程操纵器通过编程以取代成千上万的继电器。 可编程操纵器最初应用于汽车制造业中，软

件修改取代了硬连线操纵面板的从头布线，这标志着生产模式发生了完全的改变。

许多初期的PLC设计说明，在简单的梯形逻辑的决策中，已经显现了类似梯形图的电气原理图。电工们通过利用梯形逻辑能够很方便的查找出电路示用意的问题。这项打算符号的选择利用能够降低培训其现有的技术人员的要求。而其他初期的PLC那么利用一种基于堆栈的逻辑解决方式——指令表编程的方式。

PLC的功能通过量年的进展，已经包括顺序操纵，运动操纵，进程操纵，散布式操纵系统和网络操纵系统等多个方面。一些现代的PLC的数据处置、贮存、整理和通信能力已大约相当于台式电脑了。可编程操纵器的编程结合远程I/O硬件，许诺通用台式电脑进行一些PLC方面的特定应用。

依照国际电工委员会61131-3标准，PLC的编程能够利用基于标准的编程语言。所谓顺序功能图的图形符号编程适用于某些特定的可编程操纵器。

可编程操纵器与其他操纵系统

PLC能够专门好的适应各类自动化任务。这些都是典型的工业机械生产，这些部门自动操纵系统的高额费用是与其昂贵的的制造保护费用分不开的。PLC能操纵输入输出设备并兼容工业实验装置和操纵。通常PLC应用于高度定制的系统,以便使组装PLC的本钱低于设计操纵器的本钱。另外，在大规模生产产品方面，自概念的操纵系统是经济的，由于他的组成部份本钱较低。这是代替通用解决方案的最正确选择。

为大量量或简单的固定自动化任务，不同的技术被采纳。例如：消费者洗碗机被本钱只有几美元的机电凸轮计时器操纵。

微处置器的设计要考虑成百上千的组成单元，以便开发本钱（电源供给器和输入输出硬件的设计）能遍及到很多销售领域，而且最终用户不需要改变操纵。汽车应用是一个例子，每一年有数以百万辆汽车被制造，只有极少数最终用户改变操纵程序。但是，一些特殊车辆，如利用PLC系统代替定制设计操纵的过境巴士因为利用量少因此开发费用不够经济。

复杂的进程操纵，如用于化学工业的进程操纵要求的算法和性能乃至超过了高性能的PLC操纵。高速度和精度的操纵也可能需要量身定制的解决方案，如飞机的飞行操纵。

PLC系统包括逻辑单变量反馈模拟操纵回路，一个“比例、积分、导数”或“操纵器”。PID回路可用于操纵制造进程的温度，例如历史上的PLC通常只用于少数模拟操纵回路那个进程需要成百上千的循环、散布式操纵系统（DCS）将代替利用。但是，由于PLC的功能愈来愈壮大，DCS与PLC的界定越发的不明确。

数字和模拟信号

数字或离散信号表现为二进制开关信号，收益率只是一个闭合或关断信号。按钮、限位开关、光电传感器能提供了一个离散信号。离散信号以电压或电流的形式传送，它在一个特定的范围内被设置成开和关。例如：PLC必需利用24伏直流电压的I/O口，高于22伏直流电压代表开，低于2伏直流电压代表关，中间值不确信。最初，PLC只有离散的I/O接口。

模拟信号和音量操纵一样，在零和满量程之间有一系列的值。这些常常被概念为PLC中的整数，它的范围取决于设备中可用来存储比特数据的存储单元的数量。由于PLC通常利用16位有符号二进制处置器，整数值被限定在-32768—+32767之间。压力、温度、流量、重量往往代表的模拟信号。模拟型号能够利用与原信号成正比的电压或电流信号。例如：一个4-20mA的电流信号或0-10V的电压信号将被转化成一个0-32767之间的整型值。

编程

初期的PLC（直至20世纪80年代中期）利用专有的编程渠道或特殊用途的编程终端进行编程。它们是用来取代继电器逻辑系统的。这些PLC用梯形图编程，其超级类似于继电器逻辑示用意。现代的PLC能够以各类方式编程，从梯形图到更传统的编程语言，如BASIC和C，另一种高级程序设计语言是State Logic，它是基于状态转移图设计PLC程序的。

最近，国际标准IEC61131-3已经流行。目前的IEC61131-3为可编程操纵系统概念了5编程语言：FBD（功能框图），LD（梯形图），ST（结构化文本），IL（指示表）和SFC（顺序功能图）。这些技术强调动作的逻辑组织。

所有制造商PLC编程的大体概念是一起的，不合在于I/O的选择，存储组织的安排和指令集，因此不同生产商之间的PLC程序从来都不能够完全的互换。即便是同一制造商同一产品线，不同的模式也可能无法兼容。

用户界面

PLC为了配置，报警或日常操纵的目的可能需要人机互动交流。HMI（人机界面）因此而产生。人机界面包括MMI（人机接口）和GUI（图形用户界面）。

一个简单的系统能够利用按钮和灯来与用户互动。文字显示和图形化的触摸屏也可能用到。最现代的PLC能够通过网络连接到其他的系统，如运行SCADA（监控和数据搜集系统）的运算机系统或网络阅读器。

通信

PLC的内置通信端口通常利用9针的RS232串口 ，并选择性利用RS485的和以太网。Modbus协议或DF1是经常使用的一种通信协议。其他通信协议包括各类现场总线，如DeviceNet现场总线或Profibus现场总线等。

历史

PLC是应美国汽车业进展的需要而产生的。在PLC产生之前，汽车利用继电器进行顺序操纵和平安联锁逻辑，制造按时器和专用闭环操纵器。每一年模型转换是超级耗时和昂贵的，而且中继系统需要有熟练的电工才能操作。在1968年通用汽车公司发出一份为硬连线中继系统寻觅一个电子替代品的建议书。

中标投标书来自贝德福德，马萨诸塞州的贝德福德联营公司。第一个PLC，被命名为084 ，因为它是贝德福德的第八十四个项目的结果。贝德福德联营协会创建了一个新的公司，它致力于开发，制造，销售和效劳这一新产品：莫迪康，它代表模块化数字操纵器。该项目主持者切尼莫雷，

被以为是“PLC之父”。该莫迪康品牌在1977年被古尔德电子收购，后来又被德国AEG公司收购，然后是法国施耐德电气，也是目前的所有者。

汽车行业仍然是最大的一个PLC用户，莫迪康仍然标称一些操纵器的模型。PLC应用在许多不同的行业和机械上，如包装机和半导体设备。众所周知，PLC的品牌有东芝，西门子，艾伦布拉德利，ABB，三菱，欧姆龙和通用电气等。