外文翻译---PLC在回旋加速器控制上的应用

附件 3：外文文献原文 PLC Application in the Control of CIAE-30 Cyclotron 此文选自： PLC&FA 作者： Li Zhenguo 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 ON an output signal to some sort of output devices. In an automated system, the PLC is commonly regarded as the heart of the control system. With a control application program (stored within the PLC memory) In execution, the PLC constantly monitors the state of the system through the field input devices’ feedback signal. It will then based on the program logic to determine 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 technology, complicated control tasks accomplished with a highly automated control system, which may be in the field devices （ such as operator panel, motors, sensors, switches, solenoid valves and etc.） , capabilities in network communication enable a big scale implementation and process co-ordination besides providing greater flexibility in realizing distributed control system. Every single 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 usually developed by a system integrator as EID ELECTRONICS for a dedicated process control. Depending on the size of target process and the operational requirements, the structures of PLC control system can vary. More often, a supervisory control and data acquisition system is applied, this is the HMI. Such system consists of a PLC based control on the plant level, graphic screen interface on the operation level, and processing server on the management level. 2 PLC application——PLC-controlled mini-cyclotron CIAE-30 compact cyclotron is a new kind of accelerator dedicated to medical radio-isotope production. Its main features are compact structure, low power consumption, high beam intensity and easy change of energy. It consists of complex equipment, e.g. external ion source, magnet, R.F. generator, stripper, vacuum, water cooling, pneumatic activator, transportation line, beam diagnostics, targetry and various power supplies. The whole production process includes H- beam production, acceleration, electron stripping, extraction, focusing, transportation, target control, radioisotope analyses and sampling. Fig.1 shows the main body of CIAE-30 cyclotron. The control hardware consists of two parts: PLC modules and operation console. PLC modules include: three CPUs (922R), one coordinator (923C), a number of analog and logical I/Os, one communication processor (CP527), one intelligent processor(IP241), special bus and internal supplies. Operation console includes: a keyboard, a large high resolution colour monitor, two encoders, beam diagnosis and a printer. PLC communicates with the cyclotron equipment through the logical and analog I/Os, which translate orders to and receive status messages from all the different devices. The PLC communicates with the console through the communication and intelligent interfaces, which receive operator instructions and transmit the processed status signals to be displayed on the screen or printed on Fig.1PLC communicates with the cyclotron equipment through the logical and analog I/Os, which translate orders to and receive status messages from all the different devices. The PLC communicates with the console through the communication and intelligent interfaces, which receive operator instructions and transmit the processed status signals to be displayed on the screen or printed on paper. All analog parameters of the cyclotron can be adjusted using the two encoders. The cyclotron status can be clearly graphically displayed on the monitor screen. These screens are called 'page's. Every page not only displays the key parts of the different systems, but also gives the real time dynamic messages by changing colour or positions. Different pages also assign different meanings to the function keys, according which the operator can choose appropriate instructions to the PLC. Fig.3 shows the page structure of the operation synopsis. Two encoders can be assigned to any of the analog parameters for tuning at any time. These parameters directly determine the cyclotron specifications, e.g. beam energy, intensity, extraction efficiency and ratio of the beam distribution among different targets. Different set of parameters can be stored into the PLC library, which is able to contain up to 50 sets and any of them can called into operation when necessary, that significantly saves machine tuning time and improves operation efficiency.