可編程控制器中英文翻譯@外文翻譯@外文文獻(xiàn)翻譯

外文原文： Introduction to PLC In order to use the advantages of all those controllers and eliminate the difficulties, the programmable logic controllers were invented. programmable logic controllers (PLCs), also referred to as programmable controllers, are in the computer family.A PLC was replacement for relay devices. They are programmed using a ladder diagram,which is standard electric wiring diagram. As PLC become more flexible, high-level as well as low-level languages are available to PLC programmers. PLC have the flexibility of computers as well as a standard and ersy interface with processes and other devices. They are used in commercial and applications. They are widely acceped in industry for controlling from a single device to a complex manufacturing facility. programmable logic controllers were first introduced in 1968 as a substitute for hardwired relay panels. The original intent was to replace a mechanical switching device (relay modules).However,since 1968, the capabilities of the PLC were to replace relay panels,modern PLC have many more functions. Their use extends from simple process control to manufacturing system controls and monitoring. They are used for high-speed digital processing, high-speed digital communication, high-level computer-language support, and, of course, for basic control. PLC vary in size and power. A large PLC can have up to 10000 I/O points and support all the functions discussed earlier. There are expansion slots to accommodate PC and oter communitions decices. For many applications, a small PLC is sufficient. The speed of PLC is constantly improving, even the low-end PLC perform at high speed. One to two microsec / kbyte of memory speed is very common. Programmable logic controllers Architecture The basic components in a relay panel circuit and the design of a relay ladder diagram have been discussed. In the implementation of such a circuit, not only doesthe logic problem have to be thought out, but alse the electrical compatibility and wiring layout have to be considered. Breadboarding a relay panel circuit is a tedious task； it requires a lot of careful planning and work. The debugging and changing of a circuit is even more difficult. Programmable logic controllers replace most of this wiring by software programming. Therefore, the task is made much easier, because the wires and the moving mechanical components (relay contacts) are mostly replaced by software, the system is much more reliable. Like a general-purpose computer, a programmable controller consists of five major parts； CPU (processor), memory, input/out (I/O), power supply, and peripherals. Programmable logic controllers Functions and Configurations. 1 Basic PLC Operation PLC consist of input modules or poits, a Central Processing Unit (CPU), and output modules or points. An input accepts a variety of digital oranalog signals from various field devices (sensors) and converts them into a logic signal that can be used by the CPU. The CPU makes decisions and executes control instructions based on program instructions in memory. Output modules convert convert control instructions from the CPU into a digital or analog signal that can be used to control various field devices (actuators). A programming device is used to input the desired instructions. These instructions determine what the PLC will do for a specific input. An operator interface device allows process information to be displayed and new control paramenters to be entered. Pushbuttons (sensors), connected to PLC inputs, can be used to start and stop a motor connected to a PLC through a motor starter (actuator). 2 Hard-Wired Control Prior to PLC many of these control tasks were solved by contactors or relay controls. This is often referred to as hardwired control. Circuit diagrams had to be designed. Electrical components specified and installed, and wiring lists created. Electricians would then wire the components necessary to perform a specific task. If an error was made the wires had to be reconnected correctly. A change in function or expansion required wxtensive component changes and rewiring. 3 Advantages of PLC The same, as well as more complex tasks, can be done with a PLC. Wiring between devices and relay cintacts is done in the PLC program. Hard-wiring, though still required to connect field device, is less intensive. Modifying the application and correcting errors are easier to handle. It is easier to create and chang a program in a PLC than it is to wire and rewire a circuit. Following are just a few of the advantages of PLC: Smaller physical size than hard-wire solution. Easier and faster to make changes. PLC have integrated diagnostics and override dunction. Applications can be immediately documented. Applications can be duplicated faster and less expensively. 4 Siements PLC Siements makes several PLC product lines in the SIMATIC S7 family. They are: S7-200, S7-300, S7-400. (1) S7-200 The S7-200 is referred to as a micro-PLC because of its small size. The S7-200 has a brick design which means that the power supply and I/O terminal are on-board. The S7-200 can be used on smaller, stand-alone applications such as elevators, car washes, or mixing machines. It can also be used on more complex industrial applications such as bottling and packaging machines. (2) S7-300 and S7-400 The S7-300 and S7-400 PLC are used in more complex applications that support a greater number of I/O poits. Both PLC are modular and expandable. The power supply and I/O consist of separate modules connected to be the CPU. Choosing either the S7-300 or S7-400 depends on the complexity of the task and possible future expansion. Your Siemens sales representative can provide you with additional information on any of the Siemens PLC. 5 CPU CPU is a microprocessor system that contains the system memory and is the PLC decision-making unit. The CPU monitors the inputs and makes decisions based on instructions held in the program memory. The CPU performs relay, couting, timing, data comparison, and sequential operations. 6 Programming Devices The program is created in a programming device (PG) and then transferred to the PLC. The program for the S7-200 can be created using a dedicated Siemens SIMATIC S7 programming device, such as a PG 720 or PG 740, if STEP 7 Micro/WIN software is installed. A personal computer (PC), with STEP 7 Micro/WIN installed, can also be used as a programming device with the S7-200. 7 Software A software program is required in order to tell the PLC what instructions it must follow. Programming software is typically PLC specific. A software package fo r one PLC ,or one family of PLC ,such as the S7 family, would not be useful on other PLC. The S7-200 uses a Windows-based software program called STEP -7 Micro/WIN32, The PG 720 and PG 740 computer in a similar manner to any other computer software. 8 Connector Cables PPI (Poit-Poit Interface) Connector cables are required to transfer data from the program the programming device to the PLC. Communication can only take place when the two device speak the same language or protocol. Communication between programming device and the S7-200 is referred to as PPI protocol. An appropriate cable is required for a programming device such as a PG 720 or PG 740. The S7-200 uses a 9-pin,D-connector. This is a straight-through serial device that is compatible with Siemens programming devices (MPI port) and is a stangard connector for other serial interface. A special cable,referred to as a PC/PPI cable, is needed when a personal computer is used as a programming device. This cable allows the serial interface of the PLC to communicate with the RS-232 serial interface of a personal computer. DIP switched on the PC/PPI cable are used to select an appropriate speed (bit rate) at which information is passed between the PLC and the computer. 譯文： 可編程控制器 為了利用那些控制器的優(yōu)勢，消除弊端，可編程邏 輯控制器（ PLC）應(yīng)運(yùn)而生，可編程邏輯控制器（ PLC），也就是可編程控制器，是計(jì)算機(jī)家族的一員。一個 PLC 就是能代替整個繼電器控制裝置，它們用梯形圖（梯形圖是標(biāo)準(zhǔn)的電路圖）。由于 PLC 的編程靈活性逐漸增強(qiáng)，既可使用高級語言也可使用低級語言。PLC 不僅具有計(jì)算機(jī)的靈活性，同時(shí)也具有與處理過程及其他裝置連接的界面標(biāo)準(zhǔn)簡易的特點(diǎn)。它們被應(yīng)用于商業(yè)和工業(yè)領(lǐng)域，在工業(yè)上，從單一設(shè)備到復(fù)雜的制造設(shè)備都廣泛使用 PLC 控制。 可編程邏輯控制器（ PLC）于 1968 年被首次使用，用來替代一個硬接線的繼電器控制板。最初目的是替代 機(jī)械開關(guān)裝置（繼電模塊）。然而，自從 1968 年以來， PLC 的功能逐漸代替了繼電器控制板，現(xiàn)代 PLC 具有更多的功能。其用途從單一過程控制延伸到整個制造系統(tǒng)的控制和監(jiān)控。 可編程控制器也可用在高速數(shù)字處理、高速數(shù)字通信以及高級計(jì)算機(jī)語言的支持方面，當(dāng)然也可用于基本的過程控制。 PLC 在尺寸和功率上不盡相同，一個大型 PLC 可以有高達(dá) 10000 個輸入輸出點(diǎn)，具有前面討論過的所有功能。 PLC 有連接 PC 機(jī)和其他通信設(shè)備的擴(kuò)展槽，在很多場合下，一個小的 PLC 就足夠了。 可編程控制器的構(gòu)造 我們已經(jīng)討論了繼電器裝置面板電 路中的基本部件和繼電器梯形圖的設(shè)計(jì)。在這樣的電路設(shè)計(jì)過程中，我們不僅要認(rèn)真思考邏輯問題，而且還要對電氣兼用型和布線加以考慮。設(shè)計(jì)繼電器的面板電路是一項(xiàng)乏味的任務(wù)，它需要周密計(jì)劃和大量的工作。電路的調(diào)試和修改變得容易很多。因?yàn)閷?dǎo)線和運(yùn)動的機(jī)械部件（繼電器出頭）幾乎全部被軟件所替代，所以整個系統(tǒng)更加可靠。 像通用計(jì)算機(jī)一樣，可編程控制器由以下 5 個主要部分組成： CPU(處理器 )、內(nèi)存、輸入輸出（ I/O）、電源和外設(shè)。 可編程控制器的功能和配置 1 PLC 的基本操作 PLC 包括輸入模塊或輸入點(diǎn)、一個中央處理單元（ CPU）以及輸出模塊或輸出點(diǎn)。輸入單元可以接受來自不同現(xiàn)場設(shè)備（傳感器）的各種數(shù)字或模擬信號，然后將它們轉(zhuǎn)換為 CPU 可以使用的邏輯信號。 CPU 根據(jù)存儲器中的程序指令做出判斷，然后執(zhí)行指令。輸出模塊將來自 CPU 的控制指令轉(zhuǎn)換為現(xiàn)場控制的各個設(shè)備（執(zhí)行機(jī)構(gòu)）所能使用的數(shù)字或邏輯信號。編程設(shè)備用于輸入期望指令，由這些指令來決定對于特定的輸入 PLC 做什么。操作界面能夠顯示過程信息及輸入新的控制參數(shù)。連接到 PLC 輸入端的按鈕 ,通過電動機(jī)的啟動器可以啟動和停止與 PLC 連接電動機(jī)。 2 硬接線控制 使用 PLC 之前，許多控制 人為是通過接觸器和繼電器來完成的。這就是經(jīng)常所說的硬接線控制。必須先設(shè)計(jì)電路圖，確定元件，并且進(jìn)行安裝以及建立接線表，電工再連接需要執(zhí)行特定任務(wù)的元件。如果接線中有一個錯誤，就必須重新連接來糾正。如果改變功能或擴(kuò)充系統(tǒng)，元件就需要大量變化，并且線路要重接。 3 PLC 的優(yōu)勢 同樣或更加復(fù)雜的任務(wù)，可以用 PLC 來做。設(shè)備同繼電器出典之間的連接由PLC 中的程序完成。硬接線雖然依然需要連接到現(xiàn)場設(shè)備，但這一要求已經(jīng)很少了。修改應(yīng)用軟件或糾正錯誤要容易些。在 PLC 中建立或修改程序比起連接或重新連接電路要容易。 下面 列出的知識 PLC 的一小部分優(yōu)點(diǎn)： 比通過硬接線方式的物理尺寸小 修改時(shí)更簡單且更快速 PLC 有綜合診斷和忽略功能 應(yīng)用軟件能被立即生成文件 應(yīng)用程序能夠被更快并且費(fèi)用更低的復(fù)制 4 西門子 PLC 西門子制造了幾種屬于 SIMATIC S7 產(chǎn)品系列的 PLC。它們是 S7-200， S7-300，S7-400。 （ 1） S7-200 S7-200 由于尺寸小，被稱為微型 PLC。 S7-200 是塊狀設(shè)計(jì)結(jié)構(gòu)，即它的電源和 I/O 都在一塊板上。 S7-200 可以被使用在小型的、獨(dú)立的應(yīng)用設(shè)備中，