英汉翻译文献

2011届毕业设计（论文）

外文翻译

系 、 部： 电气与信息工程系

学生姓名： 吴龙军

指导教师： 罗雪莲

职 称： 教授

专 业： 自动化

班 级： 自本0703班

学 号： 410070331

2011 年6月

PLC control technology Programmable logic controller (PLC) is in the program controller and

microcomputer controller is developed on the basis of microcomputer technology and

relay conventional control the combination of the concept. With the development of

science and technology, the application of PLC in industrial control more and more

widely. PLC produced so far only 30 years since the history, but have developed

rapidly and the widespread application, become the contemporary industrial

automation, one of the main pillars of industrial production in future, PLC technology

and robots and CAD/CAM technology will become production of industrial

automation tied, since the three pillars of the new industrial control device of PLC in

industrial application in importance and universality, in order to adapt to the needs of

the development of the industrial production automation, namely to PLC automatic

control system design and reliability is of great significance to the discussion.

1 The development and application of PLC

PLC is in the program controller and microcomputer controller developed on the

basis of microcomputer technology and relay conventional control the combination of

the concept. Broadly speaking, PLC is a computer system, computer has stronger than

average of industrial process connected with the input/output interface, and has

become the basic device automation control system. PLC has been used widely in

machinery, metallurgy, chemical industry, automobile, light industries, has basic

replaced traditional relays and contactor logic control. Use PLC to control the system

reliability of the equipment, its than mere relays and contactor controlling is greatly

increased.

In computer technology as the core of PLC general industrial automation devices.

It will traditional relay control system and computer technology together, high

reliability, flexible gm, easy to programming, use convenient wait for a characteristic,

therefore in recent years in the industrial automatic control, electromechanical

integration, transform traditional industries been widely used.

1.1 traditional relay control and PLC control advantages and disadvantages

In industrial automation field, PLC as automatic control, to become the most of

the automation system, but also to the equipment foundation of industrial control has

brought an unprecedented special changes. The use of PLC control system and the

traditional industry with relays, compared the industrial control system in operation,

control, efficiency and precision and other aspects have incomparable advantages. Although in industrial control system which used in the relay control equipment will

not be eliminated, but because the PLC appear have changed industrial control the

designer's design thought.

(1) control relay the shortcomings of:

Today already applied to the family and relay to the industrial control in various

fields. They than the previous product has higher reliability. However, this also is then

cause some problems. Like most control relay are long-term wear and fatigue working

conditions, easily damaged. And relay contact easy to produce the arc, even will melt

together produce false operation, cause serious consequence. Moreover, for a specific

use the equipment with hundreds of relays, and its control box will be large and heavy.

In all the load carrying cases, big relay will produce large amounts of heat and noise,

also consumes vast quantities of electricity. And relay control system must be manual

connection, installation, if there are simple change, also need to spend a lot of time

and manpower and material resources to restructuring, installation and

commissioning.

(2) programmable controller advantage, characteristics and functions:

Programmable controller to small volume powerful is known for, it not only can

easily finish order logic, motion control, timing control, count control, digital

computing, data processing, and other functions, and can be established through

input/output interface with various production machinery digital quantity and

analogue connection, so as to realize the automatic control production process.

Especially now, due to the arrival of the era of information, network, expanded the

PLC function, make it strong network communication ability, thus the more widely

used in many industries.

Compared with the traditional relays have a few big notable features: high