【正文】
員實(shí)施人工干預(yù)。如圖,四路溫度信號(hào)經(jīng)溫度變送器分別輸入到 EM235 的四個(gè)輸入通道,通過(guò) EM235 PLC 便能直接讀取模擬量的溫度信號(hào),并對(duì)其做各種運(yùn)算。 本設(shè)計(jì)中,我將使用蘇州迅鵬儀器儀表有限公司生產(chǎn)的 XPTPAV010D 溫度變送器。 熱電偶實(shí)用測(cè)量方法: 圖中 A,B 為熱電偶, C,D 為補(bǔ)償導(dǎo)線,冷端溫度為 T, E 為銅導(dǎo)線 (在實(shí)際使用的時(shí)候,可把補(bǔ)償導(dǎo)線一直延伸到配用儀表的接線端子,這是冷端溫度即為儀表接線端子所處的環(huán)境溫度 ), M 為所配用的毫伏計(jì),或者數(shù)字儀表。在日常生活中人們也常常使用這些溫度計(jì)。溫度的測(cè)量及控制對(duì)保證產(chǎn)品質(zhì)量、提高生產(chǎn)效率、節(jié)約能源、生產(chǎn)安全、促進(jìn)國(guó)民經(jīng)濟(jì)的發(fā)展起到非常重要的作用。在這個(gè)過(guò)程中, PLC 會(huì) I/O 映象存儲(chǔ)區(qū)上對(duì)應(yīng)的狀態(tài)和數(shù)據(jù)改變輸出鎖存電路上的狀態(tài),然后輸出電路驅(qū)動(dòng)根據(jù)鎖存器的狀態(tài)驅(qū)動(dòng)外圍的設(shè)備 . . PLC 主要廠家及西門子 S7— 200 調(diào)查表明,主導(dǎo)世界 PLC 市場(chǎng)的五家國(guó)際公司分別為 Siemens(西門子 )公司、AllenBradley(AB)公司、 Schneider(施耐德 )公司、 Mitsubishi(三菱 )公司、 Omrom(歐姆龍 )公司,全球 PLC 市場(chǎng)上五家公司占據(jù)了 2\3 的份額。 ( 1)、輸入采樣階段 在輸入采樣這個(gè)過(guò)程中, PLC 以掃描方式順序地讀取所有各輸入接口的狀態(tài)和許接受皖西學(xué)院本科論文(設(shè)計(jì)) 第 7頁(yè) 的各種數(shù)據(jù)數(shù)據(jù),并存儲(chǔ)到 I/O 映象存儲(chǔ)單元內(nèi)。 (3)、存儲(chǔ)器 用于存儲(chǔ)系統(tǒng)軟件的存儲(chǔ)器被稱作系統(tǒng)程序存儲(chǔ)器。 1 小型 PLC:其 I/O 點(diǎn)數(shù)小于 256,采用 8 位或 16 位單 CPU,用戶存儲(chǔ)器容量 4KB 以下。整體式PLC 的結(jié)構(gòu)簡(jiǎn)單,體積小,價(jià)格低。 當(dāng)采樣溫度低于下限,即 Q< Qmin 時(shí),進(jìn)行下限處理: Q< Qmin,說(shuō)明溫度過(guò)低,需要增加暖氣輸出以提高溫度。當(dāng)溫度在設(shè)定的范圍之內(nèi),則綠燈亮,顯示系統(tǒng)工作正常。上位機(jī)使用計(jì)算機(jī),通過(guò) VB 編寫程序,用戶直接在計(jì)算機(jī)上輸入溫室度參數(shù),即可與下位機(jī)一起實(shí)現(xiàn)溫濕度的自動(dòng)化控制。由于上面各種原因,發(fā)展研究具有我國(guó)自主知識(shí)產(chǎn)權(quán),密切符合我國(guó)國(guó)情的溫室溫度檢測(cè)與控制系統(tǒng)迫在眉睫。 1949 年,伴隨著科技的進(jìn)步與,美國(guó)了第一個(gè)可實(shí)現(xiàn)人工控制的氣候室在美國(guó)被建設(shè)起來(lái),該氣候室對(duì)于美國(guó)在植物對(duì)環(huán)境的適應(yīng)和抵抗能力的研究方面提供了技術(shù)支持。皖西學(xué)院本科論文(設(shè)計(jì)) 基于 PLC 溫室溫度檢測(cè)與控制系統(tǒng)的設(shè)計(jì) 作 者 XXX 指導(dǎo)教師 XXX 摘要 : 溫度檢測(cè)和控制對(duì)人類日常生活、工業(yè)生產(chǎn)、氣象預(yù)報(bào)、物資倉(cāng)儲(chǔ)等都起著極其重要的作用。 關(guān)鍵字 : PLC,溫度傳感器,檢測(cè) ,控制 Design of detection and control system of greenhouse temperature based on PLC Abstract: Temperature measurement and control plays an extremely important role in human daily life, including industrial production, weather forecast, material storage, etc.. In many cases, it is very important to acquire the timely and accurate information of the temperature of the targets. Recently, along with the development of digital technology, the rapid development of temperature measurement and control has been widely used in various industrial agricultural fields, meanwhile, the chips of measurement and control the temperature have been on the historical stage. This system, by collecting temperature data through the temperature sensor, with the application of PLC control system based on the theoretical knowledge about temperature measurement and control, intends to analyze the potential causes of the breakdowns in their automatic operation. At the same time, starting from the circuits of actual hardware, and via analyzing operating principles of these electric circuits, this system is aiming at putting forward the revising proposasl and solutions according to the specific situations. The temperature sensor used by the author is XPTPAV010D, which is distinguished with small size, high precision and low power consumption. The temperature data collected by the temperature sensor is an analog signal. Therefore, in the system, an analog extended module of will be added to the PLC so that temperature signal collected by 皖西學(xué)院本科論文(設(shè)計(jì)) the module can be directly input to PLC, and PLC will analyze, process the data, and control the temperature through regulating the ponents. This kind of automatic and intelligent disposure will be definitely in infinite application and tremendous development in the temperature controlling system in the greenhouse. Keyword: PLC, Temperature sensors, Detection, Control 皖西學(xué)院本科論文(設(shè)計(jì)) 目錄 ............................................................. 1 ..............................