基于PLC的三層電梯控制

基于PLC的三層電梯控制,基于,PLC,三層,電梯,控制 Programmable logic controller A programmable logic controller (PLC) or programmable controller is used for electrical and mechanical process automation of the digital computer, such as control of machinery on factory assembly lines, amusement facilities, or lighting. Programmable controller is used in many industries and machines. Unlike general-purpose computers, the PLC is designed for multiple inputs and output arrangements, extended temperature ranges, immunity to electrical noise, and resistance to vibration and impact. Programs to control machine operation are typically stored in battery-backed or non-volatile memory. A PLC is a real time system since output results must be produced in response to input conditions within a bounded time; otherwise it will lead to wrong operation 1. Development Early PLCs were designed to replace relay logic systems. These "ladder logic" of the programmable controller is a very similar with the relay logic diagrams. Select representation for the purpose of this procedure is to reduce the existing technical personnel's training needs. Other early programmable controller using instruction list programming, programming logic solver is based on a stack. Modern PLCs can be programmed in a variety of ways, from ladder logic to more traditional programming languages such as BASIC and C. Another method is State Logic, a very high-level programming language designed to program PLCs based on state transition diagrams. Many early PLCs did not have accompanying programming terminals that were capable of graphical representation of the logic, and so the logic was instead represented as a series of logic expressions in some version of Boolean format, similar to Boolean algebra. As programming terminals evolved, it became more common for ladder logic to be used, for the aforementioned reasons. Update format such as logic and function block (this is a similar logic description using digital logic integrated circuit), but they are still not popular ladder logic language. A major reason is that the programmable controller to solve the problem in a predictable and repeating sequence logic, and ladder logic language can use other formats for programmers (write logic), people see the logic of time, all the problems more easily programmed. 2. Functionality The functionality of the PLC has evolved over the years to include sequential relay control, motion control, process control, distributed control systems and networking. The data handling, storage, processing power and communication capabilities of some modern PLCs are approximately equivalent to desktop computers. PLC-like programming combined with remote I/O hardware, allow a general-purpose desktop computer to overlap some PLCs in certain applications. Regarding the practicality of these desktop computer based logic controllers, it is important to note that they have not been generally accepted in heavy industry because the desktop computers run on less stable operating systems than do PLCs, and because the desktop computer hardware is typically not designed to the same levels of tolerance to temperature, humidity, vibration, and longevity as the processors used in PLCs. In addition to the hardware limitations of desktop based logic, operating systems such as Windows do not lend themselves to deterministic logic execution, with the result that the logic may not always respond to changes in logic state or input status with the extreme consistency in timing as is expected from PLCs. Still, such desktop logic applications find use in less critical situations, such as laboratory automation and use in small facilities where the application is less demanding and critical, because they are generally much less expensive than PLCs. In more recent years, small products called PLRs (programmable logic relays), and also by similar names, have become more common and accepted. These are very much like PLCs, and are used in light industry where only a few points of I/O (i.e. a few signals coming in from the real world and a few going out) are involved, and low cost is desired. These small devices are typically made in a common physical size and shape by several manufacturers, and branded by the makers of larger PLCs to fill out their low end product range. Popular names include PICO Controller, NANO PLC, and other names implying very small controllers. Most of these have between 8 and 12 digital inputs, 4 and 8 digital outputs, and up to 2 analog inputs. Size is usually about 4" wide, 3" high, and 3" deep. Most of these devices have a LCD screen to watch the size of a small stamp simplified the ladder logic input/output point (only a small part of the program being visible at a given time) and status, and the screen by an electromagnetic four-way rocker button control combined with four different used to view and edit the logic of the button, similar to video remote control button. Most controllers has a small socket to connect through the RS - 232 or RS - 485 and personal computers, so that programmers can use for programming simple Windows application rather than forced to use a small LCD and button. Unlike ordinary PLC, is usually a modular, greatly expanded, controller does not usually take modular and extensible, not but they provide robust design of certainty and perform logic value less than PLC. 3. PLC Topics 3.1System scale A small PLC is a fixed number of input and output generated connection. If the base model has enough I/O usually can be extended. Modular programmable controller has a chassis (also called a rack) in which place has a different function module. The choice of processor and I/O module is customized for a particular application. Several racks can have a single processor; there may be thousands of input and output. A kind of special high speed serial I/O link is the frame to reduce multiple lines using distributed discrete processors. 3.2User interface PLCs may need to interact with people for the purpose of configuration, alarm reporting or everyday control. A simple system may use buttons and lights to interact with the user. Text displays are available as well as graphical touch screens. More complex systems use a programming and monitoring software installed on a computer, with the PLC connected via a communication interface. 3.3Communications PLCs have built in communications ports, usually 9-pin RS-232, but optionally EIA-485 or Ethernet. Modbus, BCAnet or DF1 is usually included as one of the communications protocols. Other options include various fieldbuses such as DeviceNet or Profibus. Other communications protocols that may be used are listed in the List of automation protocols. Most modern PLCs can communicate over a network to some other system, such as a computer running a SCADA (Supervisory Control And Data Acquisition) system or web browser. PLCs used in larger I/O systems may have peer-to-peer (P2P) communication between processors. This allows separate parts of a complex process to have individual control while allowing the subsystems to co-ordinate over the communication link. These communication links are also often used for HMI devices such as keypads or PC-type workstations. 3.4Programming PLC programs are typically written in a special application on a personal computer, and then downloaded by a direct-connection cable or over a network to the PLC. The program is stored in the PLC either in battery-backed-up RAM or some other non-volatile flash memory. Often, a single PLC can be programmed to replace thousands of relays. Under the IEC 61131-3 standard, PLCs can be programmed using standards-based programming languages. A graphical programming notation called Sequential Function Charts is available on certain programmable controllers. Initially most PLCs utilized Ladder Logic Diagram Programming, a model which emulated electromechanical control panel devices (such as the contact and coils of relays) which PLCs replaced. This model remains common today. IEC 61131-3 currently defines five programming languages for programmable control systems: FBD (Function block diagram), LD (Ladder diagram), ST (structured text, similar to the PASCAL programming language), IL (teaching list, similar to the assembly language) and the SFC (sequential function chart). These techniques emphasize the logical operation of the organization. Although the basic concept of PLC programming is common all producers, I/O, memory organization and instruction set different Settings PLC program means not completely interchangeable. Even within a single manufacturer product line may not be directly compatible with different models. 4. Digital and analog signals Digital or discrete signal like a binary switch, create a simple on or off the signal (1 or 0, respectively, true or false). Button, limit switches and photoelectric sensor is to provide discrete signal equipment. Discrete signals are sent using either voltage or current , where a specific range is designated as On and another as Off. For example, a PLC might use 24 V DC I/O, with values above 22 V DC representing On, values below 2VDC representing Off, and intermediate values undefined. Initially, PLCs had only discrete I/O. Analog signal like the volume control range from 0. This is often interpreted as an integer value (count), PLC and range of accuracy depends on the equipment and the number of bits used to store the data. Programmable controller usually use 16-bit processor binary symbols, range - an integer value between 32768 and 32767. Pressure, temperature, flow, and weight are often represented by analog signals. Analog signals can use voltage or current with a magnitude proportional to the value of the process signal. For example, a simulation of 0-10 v or 4-20 mA input will be converted to an integer value 0-32767. 可編程邏輯控制器 可編程邏輯控制器（PLC）或可編程序控制器是用于機電過程自動化的數(shù)字計算機，例如控制機械廠生產(chǎn)線、游樂設(shè)施或照明裝置?？删幊炭刂破髟谠S多工業(yè)和機器中使用。與通用的計算機不同的是，PLC是專為多個輸入和輸出管理，擴展溫度范圍、不受電磁噪音影響、抗震動和沖擊所設(shè)計。控制器的操作程序通常存儲在電池供電或非易失性的內(nèi)存中。PLC是實時的系統(tǒng)，因為系統(tǒng)產(chǎn)生的輸出結(jié)果必須在有限的時間內(nèi)回饋到輸入，否則會導致錯誤操作。 1.發(fā)展 早期的可編程控制器是設(shè)計來取代繼電器邏輯系統(tǒng)。這些可編程控制器的“階梯邏輯”是與繼電器邏輯示意圖非常類似的。選擇此程序表示法的目的是為了減少對現(xiàn)有技術(shù)人員的培訓需求。其他早期的可編程控制器使用指令列表編程，基于一個堆棧編程邏輯求解器進行求解。 現(xiàn)代可編程控制器在各種各樣的方式可以被編程，從梯形邏輯語言到更加傳統(tǒng)的編程語言例如BASIC和C語言。另一個方法是狀態(tài)邏輯，被設(shè)計的一種非常高級編程語言根據(jù)狀態(tài)轉(zhuǎn)換圖的可編程控制器編程。 很多早期可編程控制器沒有可編程終端的邏輯圖形表示法，邏輯反而是被描繪成一系列在一些版本的布爾格式的邏輯表達式，類似于布爾代數(shù)。隨著編程碼發(fā)展，由于上述原因它變成更常見的梯形邏輯語言。更新的格式如國家邏輯和功能塊（這是類似的邏輯描述使用數(shù)字邏輯集成電路時的方式）的存在，但它們?nèi)詻]有梯形邏輯語言流行。一個主要原因是可編程控制器解決問題用一個可預測和重復的序列的邏輯，并且梯形邏輯語言可以用其他格式讓程序員（寫邏輯）的人看到邏輯的時間，所有問題更加容易地程序化。 2.功能 PLC的功能經(jīng)過多年的發(fā)展，包括連續(xù)的繼電器控制，運動控制，過程控制，分布式控制系統(tǒng)和網(wǎng)絡(luò)。一些現(xiàn)代PLC的數(shù)據(jù)處理，存儲，處理能力和通信能力相當于臺式電腦。PLC編程結(jié)合遠程I/O硬件，一臺通用臺式計算機允許在某些應用中重疊使用某一可編程控制器。在重工業(yè)中PLC被認為沒有這些桌面計算機為主的邏輯控制器的實際性強，因為PLC在臺式計算機系統(tǒng)中運行不是很穩(wěn)定，并且，因為臺式計算機硬件沒有被設(shè)計成耐溫度、濕氣、振動和耐用作為可編程控制器的處理器。除桌面基于邏輯的硬件局限之外，例如Windows操作系統(tǒng)不適合自己的確定性邏輯的執(zhí)行，結(jié)果是PLC邏輯不可能總是對規(guī)定邏輯變化的輸入狀態(tài)與極端性預計的時間一致。盡管如此，這樣桌面邏輯被應用在較不重要情況，像實驗室自動化和小型設(shè)施中使用該應用程序的要求不高，因為他們的價格一般都遠遠低于昂貴的PLC。 在最近數(shù)年，小產(chǎn)品稱為PLR（可編程邏輯繼電器），并且因為名字相似，變得更常見并被接受。這些很像PLC已經(jīng)應用于輕工業(yè)，它只有少部分的輸入/輸出（例如一些真實的輸入輸出信號）參與，低成本，很理想。這些小設(shè)備尺寸和形狀比較普通地幾位制造商制作，并且由更大的PLC制作商來填滿他們低端產(chǎn)品規(guī)格。俗名包括PICO控制器、納米PLC和其他的小控制器。多數(shù)這些控制器有在8到12數(shù)字輸入、4到8數(shù)字輸出，多達2個模擬輸入。尺寸通常是4英寸寬、3英寸高、3英寸深。大多數(shù)這樣的設(shè)備有一個小郵票大小的液晶屏幕來觀看簡化梯子邏輯的輸入/輸出點（只有一小部分程序被可見于給定的時間）和狀況，并且這些屏幕由一個電磁四通搖臂按鈕操縱加上四個不同的用于瀏覽和編輯的邏輯電鈕，類似于錄像機遙控按鈕?？刂破鞔蠖鄶?shù)有一個小插座為通過連接RS-232或RS-485到個人計算機，以便程序員可能為編程使用簡單的窗口應用而不是被迫使用微小的LCD和電鈕。不像普通PLC，通常是模塊化，大大擴展,控制器通常不會取模塊化并且不是可擴展的，但是他們提供穩(wěn)健設(shè)計的確定性和執(zhí)行邏輯的價值比PLC少。 3.可編程序控制器PLC 3.1系統(tǒng)規(guī)模 一個小的PLC是固定數(shù)量的輸入和輸出生成的連接。如果基礎(chǔ)模型具有足夠的I/O通?？蓴U展。 模塊化可編程控制器有一個機箱（也稱為機架）在其中放置具有不同的功能模塊。處理器和I/O模塊的選擇被定制為特定的應用程序。幾個機架可以有一個單個的處理器，可能會有成千上萬的輸入和輸出。一種特殊的高速串行I/O環(huán)節(jié)是機架減少多個線路使用分布式離散處理器。 3.2使用界面 可編程控制器的配置、報警報告或日?？丶赡苄枰c人進行交互。 一個簡單的系統(tǒng)可能使用按鈕和指示燈與用戶進行交互?？梢杂脠D形觸摸屏文本顯示。更復雜的系統(tǒng)使用PLC通過通信接口連接到一臺計算機上安裝的編程和監(jiān)測軟件來使用。 3.3通信 可編程控制器被建于通常的9針RS-232，也可以選擇485或以太網(wǎng)的通信端口由環(huán)境影響評估。協(xié)議、BACnet或東方是通常作為通信協(xié)議之一包含其中。其它選項包括各項如構(gòu)架或現(xiàn)場總線。在自動化協(xié)議的列表中列出了其他可能使用的通信協(xié)議。 最現(xiàn)代的可編程控制器可以通過一個網(wǎng)絡(luò)，以一些其它的系統(tǒng)（例如，運行監(jiān)控、監(jiān)測控制與數(shù)據(jù)采集 系統(tǒng)）或網(wǎng)絡(luò)瀏覽器的計算機進行通信。 可編程控制器在較大的I/O系統(tǒng)中使用可能會有處理器之間的對等，這允許獨立的部分是一個復雜的過程,同時讓獨立的控制子系統(tǒng)的溝通聯(lián)系協(xié)調(diào)。這些通信鏈接也經(jīng)常用于人機界面設(shè)備（例如鍵盤或PC型工作站）。 3.4編程 PLC程序通常是個人的計算機上寫入一個特殊的應用程序，然后通過連接電纜或以上PLC網(wǎng)絡(luò)直接下載。該程序存儲在PLC備用電池內(nèi)存或一些其他非易失性閃存中。通常，一個單一的PLC可以進行編程，以替換數(shù)以千計的繼電器。 根據(jù)IEC61131-3的標準可以使用基于標準的編程語言編程PLC?？稍谀承┛删幊炭刂破魃险{(diào)用順序功能圖圖形編程表示法。最初大多數(shù)可編程控制器利用階梯邏輯圖的模式，模擬機電控制面板設(shè)備（如繼電器與線圈的聯(lián)系）。此模型今天仍然是常見的。 IEC61131-3當前定義的可編程控制系統(tǒng)的五個編程語言：FBD（功能塊圖）LD（梯形圖）、ST（結(jié)構(gòu)化文本，類似于帕斯卡爾的編程語言）、IL（教學列表，類似于匯編語言）和SFC（順序功能圖）。這些技術(shù)強調(diào)邏輯組織的行動。 雖然PLC編程的基本概念是共同所有的生產(chǎn)商，I/O處理、內(nèi)存組織和指令集不同設(shè)置PLC程序意味著不會不完全的可互換。即使在同一個單一的制造商產(chǎn)品線內(nèi)不同的模型可能不直接兼容。 5.數(shù)字和模擬信號 數(shù)字或離散信號就像二進制開關(guān)，創(chuàng)造出一個簡單的開或關(guān)信號（分別為1或0，真或假）。按鈕、限制的交換機和光電傳感器都是提供一個離散的信號的設(shè)備。離散信號發(fā)送使用電壓或電流，在特定的范圍，對指定，另一個為關(guān)閉。例如PLC可能24V直流I/O，使用值為以上22DC 代表上，2VDC下面的值表示關(guān)閉，和中間值未定義。最初，可編程控制器只有離散的I/O。 模擬信號就像音量控制范圍從0開始。這些通常被解釋為整數(shù)值（計數(shù)），PLC與各種范圍的精度取決于設(shè)備和用于存儲數(shù)據(jù)的位數(shù)?？删幊炭刂破魍ǔＪ褂?6位二進制符號的處理器，范圍-32768和32767之間的整數(shù)值。通常由模擬信號表示壓力、溫度、流量和重量。模擬信號可以使用大小成比例電壓或電流過程信號的值。例如一個模擬0-10V或4-20mA的輸入將轉(zhuǎn)換為一個整數(shù)值0-32767。 9