PLC控制器中英對(duì)照

1、plc(即可編程控制器) 是為了在機(jī)械控制中代替必要的繼電器時(shí)序電路而發(fā)明的一種設(shè)備。plc必須考慮它的輸入端口并且以他們的狀態(tài)為依據(jù)，來(lái)斷開(kāi)和接通它的輸出端口。用戶(hù)通常經(jīng)過(guò)給出理想結(jié)果的軟件或者上編程其進(jìn)入程序當(dāng)中。plc別用在很多的領(lǐng)域中，人們?cè)趶氖聶C(jī)械制造，包裝，材料加工等不計(jì)其數(shù)的工業(yè)生產(chǎn)中。plc是必不可少的。如果不用plc，那么將浪費(fèi)大量的時(shí)間和金錢(qián)。幾乎任何需要電器控制的設(shè)備都需要plc。例如，在開(kāi)關(guān)閉合時(shí)需要一個(gè)線圈接通5秒，然后不管開(kāi)關(guān)接通多長(zhǎng)時(shí)間都將線圈斷開(kāi)。借于此我們可以做一個(gè)簡(jiǎn)單的外部定時(shí)器。如果過(guò)程中有更多的開(kāi)關(guān)和線圈時(shí)，那就需要更的外部定時(shí)器。正如人們所見(jiàn)，越大的操

2、作系統(tǒng)就越能應(yīng)用到plc。我們可以編寫(xiě)plc的程序來(lái)計(jì)算輸入量，并且在特定的時(shí)候接通線圈。plc只要由cpu、存儲(chǔ)器、和輸入/輸出端口等組成。我們可以把plc看成一個(gè)里面充滿(mǎn)了成千上萬(wàn)的繼電器、計(jì)數(shù)器、定時(shí)器和數(shù)據(jù)存儲(chǔ)單元的一個(gè)大盒子。2. 1plc每個(gè)元件的作用 輸入繼電器（接觸器）：輸入接觸器plc與外界的連接口。輸入繼電器能接收到開(kāi)關(guān)，傳感器等元件發(fā)出的信號(hào)，并且不僅僅當(dāng)作繼電器使用而且還可以用來(lái)做晶體管。計(jì)算器：計(jì)數(shù)器用來(lái)計(jì)數(shù)。有普通計(jì)數(shù)器和高速計(jì)數(shù)器兩類(lèi)。普通計(jì)數(shù)器主要用來(lái)對(duì)程序中反映的信號(hào)進(jìn)行計(jì)數(shù)實(shí)現(xiàn)。告訴計(jì)數(shù)器則用來(lái)對(duì)高于plc掃描頻率的機(jī)外脈沖計(jì)數(shù)。計(jì)數(shù)器工作中需要一個(gè)表示計(jì)數(shù)

3、器狀態(tài)的位元件及一個(gè)存儲(chǔ)計(jì)數(shù)當(dāng)前值的字元件，也為位復(fù)合元件。定時(shí)器：定時(shí)器相當(dāng)于繼電接觸器系統(tǒng)中的時(shí)間繼電器，用于時(shí)間控制。plc中的定時(shí)對(duì)脈沖計(jì)數(shù)實(shí)現(xiàn)。由于定時(shí)器以對(duì)時(shí)基技術(shù)的方式計(jì)時(shí)，在存儲(chǔ)器數(shù)值的存儲(chǔ)單元字長(zhǎng)一定時(shí)，定時(shí)器的計(jì)時(shí)時(shí)間長(zhǎng)短就受到分辨率的影響。輸出繼電器：輸出繼電器存儲(chǔ)程序執(zhí)行的結(jié)果。每個(gè)輸出繼電器在存儲(chǔ)區(qū)中占一位，每一個(gè)輸出繼電器與一個(gè)輸出口相對(duì)應(yīng)。輸出繼電器上通過(guò)隔離電路，將程序運(yùn)算結(jié)果到輸出口并決定輸出口所連接器件的工作狀態(tài)。正常運(yùn)行中輸出繼電器的狀態(tài)只由程序的執(zhí)行決定。數(shù)據(jù)存儲(chǔ)單元：數(shù)據(jù)存儲(chǔ)單元用來(lái)存放“數(shù)字”類(lèi)數(shù)據(jù)，占用的存儲(chǔ)單元可以是字節(jié)、字，也可以是雙字。數(shù)據(jù)存

4、儲(chǔ)單元存儲(chǔ)數(shù)據(jù)量大。2. 2plc工作過(guò)程plc的工作過(guò)程是一個(gè)持續(xù)掃描的過(guò)程。通常分為3個(gè)階段。如圖1所表示：1) 輸出處理：plc在輸入采樣階段，首先掃描所有輸入端子，并將個(gè)輸入狀態(tài)存入內(nèi)存中各個(gè)對(duì)應(yīng)的輸入映像寄存器中。此時(shí)，輸入映像寄存器被刷新。接著，進(jìn)入程序執(zhí)行階段，在程序執(zhí)行階段或輸出階段，輸入映像寄存器與外界連接，無(wú)論輸入信號(hào)如何變化，其內(nèi)容保持不變，直到下一個(gè)掃描周期的輸入采樣階段，才重新寫(xiě)入輸入端的新內(nèi)容。2) 程序執(zhí)行階段：根據(jù)plc梯形圖程序掃描原則，當(dāng)指令中涉及到輸入輸出狀態(tài)時(shí)，plc就從輸入映像存儲(chǔ)器中“讀入”上一階段采入的對(duì)應(yīng)的輸入端子狀態(tài)，從輸出映像寄存器“讀入”對(duì)

5、應(yīng)元件映像寄存器的當(dāng)前狀態(tài)。然后，進(jìn)行相應(yīng)的運(yùn)算，運(yùn)算結(jié)果再存入元件的寄存器中。3) 輸出刷新階段：在所有指令執(zhí)行完畢后，輸出映像寄存器中所有輸出繼電器的狀態(tài)(接通/斷開(kāi))在輸出刷新階段存到輸出鎖存器中，通過(guò)一定方式輸出，驅(qū)動(dòng)外部負(fù)載。圖1 plc的工作原理fig.1 the process of the plca plc (programmable logic contraller) is a device that was invented to replace the necessary sequential relay circuits for machine control.the

6、plc works by looking at its inputs and depending upon their state，turning on/off its outputs.the user enters a program，usually viasoftware programmer，that gives the desired results.plc is used in many “real world”applications.if there is industry prerent，chances are good that there is a plc presrnt.

7、if you are involved in matching，packaging，material handing，automated assembly or countless other industries，you are probably already using them.if you are not，you are wasting money and time.almost any application that needs some type of electrical control has a need for a plc.for example，lett assume

8、 that that when a switch turns on we want to turn a solenoid on for 5 seconds and then turn it off regardless of how long the switch is on for.we can do this with a simple external timer.but what if the process included 10 switches and solenoids? we would need 10 external timers.but what if the proc

9、ess also needed to count how many times the switches individually turned on，we need a lot of external counters.as we can see，the bigger the process the more of a need we have for a plc.we can simply program the plc to count its inputs and turn the solenoids on for the specified time.the plc mainly c

10、onsists of a cpu，memory ares，and appropriate circuits to receive input/outputdata，we can actually consider the plc to be a box full of hundreds or thousands of separate relays，counters，times and data storage locations.1. 1the role of the each part 待添加的隱藏文字內(nèi)容3input relays-(contacts)：these are connect

11、ed to the outside world.they physically exist and receive signals from switchs，sensors，etc.typically they are not relays but rather they are transistors. counters： there again do not physically exist.they are simulated counted and they can be programmed to count pulses.typically these counters can c

12、ount up，down or both up and down.since they are simulated，they are limited in their counting speed.some manufacturers also include high-speed counters that are hardware based.we can think of these as physically existing.most times these counters can count up，down or up and down.timers：these also do

13、not physically exist.they come in many varieties and increments.the most common type is an on-delay type.others include off-delay and both retentive and non-retentive types.increments vary from 1ms through.output relays-(coils)：these are connected to the outside world.they physically exist and send

14、on/off signals to solenoids，lights，etc.they can be transistors，relays，or trials depanding upon the model chosen.data storage：typically there are registers assigned to simply store data.they are usually used as temporary storage for math or data manipulation.they can also typically be used to store d

15、ata when power is removed from the plc.upon power-up they will still have the same contents as before power was removed.very convenient and necessary!1. 2the work process of the plc a plc works by continually scanning a program.we can think of this scan cycle as consisting of three important steps，a

16、s shown in figure 1.there are typically the others are checking the system and updating the current internal counter and timer values.figure 1 the work prcess of plcstep 1 check input status：first the plc takes a look at each input to determine if it is on or off.in other words，is the sensor connect

17、ed to the first input on? how about the second input? how about the third it records this data into its memory to be used during the next step.step 2 exeaute program：next the plc executes your program one instruction at a time.maybe your program said that if the first input was on then it should tur

18、n in zhe first out.since it already kowns which inputs are on/off from the previous step，it will be able to decide whether the first output should be turned on based on the state of the first input.it will store the execution results for use later during the next step.step 3 update output status：fially the