【正文】 he inside and dealt with , sets up service of ports , procedure and inputs and deals with outside, the procedure carries out, the procedure exports several stages. The whole course is scanned the necessary time of once to call and scan cycle . Deal with stage insidly: CPU should be restored to the throne watchdog timer , hardware to check , user39。 DCS的基本組成部分 系統(tǒng)的邏輯結(jié)構(gòu)需要由物理結(jié)構(gòu)實現(xiàn)。 DCS是由計算機技術(shù)、信號處理技術(shù)、測量控制技術(shù)、通信網(wǎng)絡(luò)技術(shù)、 CRT技術(shù)、圖形顯示技術(shù)及人機接口技術(shù)相互滲透發(fā)展而產(chǎn)生的。s procedure , CPU scans the laddershaped picture one by one right, the execution of the procedure is carried on according to the priority order that the sentence is arranged , it is a kind of serial working way. Initialize at first after the electricity on PLC: Auxiliary , special auxiliary , auxiliary regional zero clearing of memory relay of I/0 , inside 。s procedure storing device , produce the corresponding control signal according to the task that the order stipulates after analysing, go to mand relevant control circuits . CPU and realizes by arithmetic unit , controller , register mainly the data , control and state bus of the connection among them are formed , unit CPU still includes peripheral chip , interface of the bus and relevant circuit. The memory is used for storing the procedure and data mainly, is indispensable position unit PLC. In user39。s station, and can control and regulate the craft course through the input equipment , so as to ensure the security of the production process , reliable , highefficient , high quality. It is colored CRT that operator39。s operator39。s engineer standing. I/O controls the station live An onthespot I / O is controlled and stood to finish dealing with and realizing the work node of digital control DDC (Direct Digital Control ) directly to onthespot I/O of course, there are three main functions: 1, which carried on digitization of various kinds of onthespot course amount (such as the flow , pressure ), and the quantity after digitizing is stored in the memory , form one keep the same with onthespot course amountly, can oneone is it video in real time according to actual running situation with newer onthespot course quantity to change in real timing。 3, the realtime trend shows: With curve say e out change recently, producting process of data, so that the operator understands its development and change to some extent, and can help to analyse the running situation of the production process .which Can generally show the trend curves of 48 data in the same system of coordinates , so can pare with all relevant data ,to make the analysis on onthespot situation very more clearly. The engineer stands It is disposed to DCS offline that the engineer stands, configuration and work node supervised , controlled , maintained online. Its main function is to finish the systematic configuration , dispose the work, and monitor the each nodal running situation when real when the line is operated, make system engineer can stand in time adjusting system disposing and some settlement of systematic parameter through engineer, to make the system in the best working state at any time. Systematic work It is all some isolated nodes that onthespot I/O is controlled and stands , stands at operator39。s Ether of interface (MPI ) work more mainly now. 2. Design basic principle of PLC control system Meet the control request which is accused of the target maximumly. On the premise of meeting control request , is it make control system simple , economy , use and maintain convenient to make every effort. Guarantee the control system is safe and reliable. Consider the development of production and improvement of the craft should leave the surplus properly while choosing PLC capacity. 3. PLC software system and daily programming language PLC software system is made up of systematic procedure and user39。s memory is checked etc. and operated. Communication operates the stage of serving: PLC and some intelligent object munication, the order that the response programmable device typed in, upgrade display content of the programmable device ,etc.. Content of operating etc. that PLC is in the state of stopping (STOP ) to only carry on the inside and to deal with and have the service of ports with outside. Deal with the inside when PLC is in the state of operating (RUN ) , setting up service of ports , proceduing inputting , procedure carrying out , proceduring to export outside, is been circulating and scanning the work all the time . 1, Input and deal with stage Input and deal with too and let introduction sample. At this stage, PLC is read into breaking the state openly of all input end sons by way of scanning, and store reading the information entered in the corresponding image register in the memory, inputting and videoing the register here and is broken, then enter the procedure and carry out stage. 2, The procedure carries out stage Carrying out stage in the procedure, PLC scans and carries out user39。我 們可以簡單將其物理結(jié)構(gòu)歸納為“三點一線”式的結(jié)構(gòu)。 Power check, memory, I / 0 and timer state of alert, and users can diagnose the procedures grammatical mistakes. 2, Memory storage system software Memory storage system software called System memory program memory. Storage application software known as the user program memory Memory 3, Power Power in the PLC system as a whole played a very important in the role. General AC voltage fluctuations in +10% (+15%), within can not take other measures to connect directly to the PLC to theAC Inter. 4, Input and output devices (I / O modules) I / O module is the scene UO CPU and other external devices or equipment connectivity between ponents. External input signal is transformed into a CPU can accept the signal, CPU or the output signal of the need to transform into a control signal to drive the