則可以用NC的辦法，進行數(shù)字量的控制。新開發(fā)的運動單元，甚至還發(fā)行了NC技術(shù)的編程語言，為更好地用PLC進行數(shù)字控制提供了方便。

　　4、用于數(shù)據(jù)采集

　　隨著PLC技術(shù)的發(fā)展，其數(shù)據(jù)存儲區(qū)越來越大。如德維森公司的PLC，其數(shù)據(jù)存儲區(qū)(DM區(qū))可達到9999個字。這樣龐大的數(shù)據(jù)存儲區(qū)，可以存儲大量數(shù)據(jù)。數(shù)據(jù)采集可以用計數(shù)器，累計記錄采集到的脈沖數(shù)，并定時地轉(zhuǎn)存到DM區(qū)中去。數(shù)據(jù)采集也可用A/D單元，當模擬量轉(zhuǎn)換成數(shù)字量后，再定時地轉(zhuǎn)存到DM區(qū)中去。PLC還可配置上小型打印機，定期把DM區(qū)的數(shù)據(jù)打出來。

　　PLC也可與計算機通訊，由計算機把DM區(qū)的數(shù)據(jù)讀出，并由計算機再對這些數(shù)據(jù)作處理。這時，PLC即成為計算機的數(shù)據(jù)終端。

　　電力用戶曾使用PLC，用以實時記錄用戶用電情況，以實現(xiàn)不同用電時間、不同計價的收費辦法，鼓勵用戶在用電低谷時多用電，達到合理用電與節(jié)約用電的目的。

　　5、用于信號監(jiān)控

　　PLC自檢信號很多，內(nèi)部器件也很多，多數(shù)使用者未充分發(fā)揮其作用。其實，可利用它進行PLC自身工作的監(jiān)控，或?qū)刂茖ο筮M行監(jiān)控。對一個復(fù)雜的控制系統(tǒng)，特別是自動控制系統(tǒng)，監(jiān)控以至進一步能自診斷是非常必要的，它可減少系統(tǒng)的故障，出了故障也好查找，可提高累計平均運行時間，降低故障修復(fù)時間，提高系統(tǒng)的可靠性。

　　6、用于聯(lián)網(wǎng)、通訊

　　PLC聯(lián)網(wǎng)、通訊能力很強，不斷有新的聯(lián)網(wǎng)的結(jié)構(gòu)推出。

　　PLC可與個人計算機相連接進行通訊，可用計算機參與編程及對PLC進行控制的管理，使PLC用起來更方便。

　　為了充分發(fā)揮計算機的作用，可實行一臺計算機控制與管理多臺PLC，多的可達32臺。也可一臺PLC與兩臺或更多的計算機通訊，交換信息，以實現(xiàn)多的對PLC控制系統(tǒng)的監(jiān)控。PLC與PLC也可通訊，可一對一PLC通訊，可幾個PLC通訊，可多到幾十、幾百。

　　PLC與智能儀表、智能執(zhí)行裝置(如變頻器)，也可聯(lián)網(wǎng)通訊，交換數(shù)據(jù)，相互操作。可聯(lián)接成遠程控制系統(tǒng)，系統(tǒng)范圍面可大到10公里或更大。可組成局部網(wǎng)，不僅PLC，而且計算機、各種智能裝置也都可進網(wǎng)。可用總線網(wǎng)，也可用環(huán)形網(wǎng)。網(wǎng)還可套網(wǎng)。網(wǎng)與網(wǎng)還可橋接。聯(lián)網(wǎng)可把成千上萬的PLC、計算機、智能裝置組織在一個網(wǎng)中。網(wǎng)間的結(jié)點可直接或間接地通訊、交換信息。

　　聯(lián)網(wǎng)、通訊，正適應(yīng)了當今計算機集成制造系統(tǒng)(CIMS)及智能化工廠發(fā)展的需要。它可使工業(yè)控制從點(Point)、到線((Line)再到面(Aero)，使設(shè)備級的控制、生產(chǎn)線的控制、工廠管理層的控制連成一個整體，進而可創(chuàng)造更高的效益。這個無限美好的前景，已越來越清楚地展現(xiàn)在我們這一代人的面前。

　　以上幾點應(yīng)用是著重從質(zhì)上講的。從量上講，PLC有大、有小。所以它的控制范圍也可大、可小。小的只控制一個設(shè)備，甚至一個部件，一個站點;大的可控制多臺設(shè)備，一條生產(chǎn)線，以至于整個工廠。可以說工業(yè)控制的大小場合，都離不開PLC。reach 9999 words. Such a large data storage area can store a large amount of data. Data acquisition can be used to accumulate the number of pulses collected and transferred to DM area regularly. Data acquisition can also be used as a/d unit. When analog quantity is converted into digital quantity, it is transferred to DM area at regular time. PLC can also be equipped with small printers, and regularly print out data in DM area.

PLC can also communicate with computer, read data of DM area by computer, and then process these data by computer. At this time, PLC becomes the data terminal of the computer.

The power users used PLC to record the user's electricity consumption in real time to realize different charging methods of different time and different pricing, encourage users to use more electricity in the low-level of electricity consumption, so as to achieve the purpose of reasonable power consumption and energy saving.

5. For signal monitoring

PLC has many self-test signals and many internal devices, and most users do not give full play to its role. In fact, it can be used to monitor the PLC itself, or monitor the control objects. It is necessary to monitor and further diagnose a complex control system, especially automatic control system. It can reduce the system fault, find fault or find fault, improve the accumulated average time without fault, reduce the time of fault repair and improve the reliability of the system.

6. For networking, communication

PLC network, communication ability is very strong, and new networking structure is constantly launched.

PLC can communicate with personal computer, and can be used to participate in programming and control PLC management, so that PLC can be used more conveniently.

In order to give full play to the role of computer, a computer can control and manage multiple PLC, and 32 can be used. One PLC can also communicate with two or more computers to exchange information to realize more monitoring of PLC control system.