单片机-PLC-外文翻译-外文文献-英文文献-PLC在回旋加速器控制上的应用.doc

附件 3：外文文献原文

PLC Application in the Control of CIAE-30 Cyclotron

1 Overview

A PLC consists of a Central Processing Unit (CPU) containing an

application program and Input and Output Interface modules, which

is directly connected to the field I/O devices. The program controls the

PLC so that when an input signal from an input device turns ON, the

appropriate response is made. The response normally involves turning

the course of action to be carried out at the field output devices. The

PLC may be used to control a simple and repetitive task, or a few of

them may be interconnected together with other host controllers or

host computer through a sort of communication network, in order to

integrate the control of a complex process.

In general, a Control System is a collection of electronic devices

and equipment which are in place to ensure the stability, accuracy and

smooth transition of a process or a manufacturing activity. It takes

any form and varies in scale of implementation, from a power plant to

a semi-conductor machine. As a result of rapid advancement of

component in a control system plays an important role regardless of

size.

A typical PLC control system consists of the hardware, software

and network components, together with the controlled functions and

associated documentation. The PLC hardware can include a rack,

power supply, CPU, network interface card, digital or analog I/O cards,

and other special purpose cards such as high-speed counter, motion

control, pulse input and others. The software portion of a PLC control

system involves firmware – which is the operating system in the PLC

world, and programming software tools and application software