The Method Selecting Type of PLC in Controlling System

摘要

When designing PLC system, first determining control scheme, the work of next step is PLC selecting type of project design. the characteristic of process and application requirement are the major accordance of designing selecting type. PLC and relevant equipments should be integrated 、 standard 、according to the principle easy to form a whole with industrial control system and easy to expand its function to select type, PLC chosen should have application achievement in related industrial field 、the maturation and reliable system, the systematic hardware 、software configuration and function of PLC should suit with installation scale and control requirement. Knowing programming controler 、function picture and relevant programming language is helpful to shorten programming time. Therefore, selecting type of project design and estimating, it should analyse the characteristic of process and control requirement in detail, definite control task and range, determing operation and movement required,then according to control ask to estimate numbers of inputs and outputs 、memory capacity required 、determing function of PLC 、the external equipment property etc. finally selecting having higher price performance PLC and desiging the corresponding control system. Along with popularization of PLC in industrial control, quantity and kind of PLC product are more and more and function also becomes perfect day by day. In recent years, the PLC products that introduced from the countries such as America 、Japan and Germany and the domestic manufacturer assembles or develops independently have had tens of series, hundreds of models. The kind of PLC is numerous, its structural model 、performance 、capacity 、instruction system and programming method etc are different, application occasion has also each to stress. Therefore, select PLC reasonably, the application for PLC in control system has important role. Along with the unceasing advance of science and technology, the kind of PLC is increasingly numerous, its function also strengthens gradually. Though the article have sumed up some methods of choosing PLC and exampled to explain how to use, in practical work it must still make proper adjustment according to practucal condition in order to design the industrial control system that satisfies expectation.