【正文】 he ground, conditions have to be very calm winds less than 2 mph, with no precipitation or humidity and limited cloud cover. The balloon, with capsule attached, will move through the lower level of the atmosphere (the troposphere) where our daytoday weather lives. It will climb higher than the tip of Mount Everest ( miles/ kilometers), drifting even higher than the cruising altitude of mercial airliners ( miles/ kilometers) and into the stratosphere. As he crosses the boundary layer (called the tropopause),e can expect a lot of turbulence. The supersonic descent could happen as early as Sunda. The weatheThe balloon will slowly drift to the edge of space at 120,000 feet ( Then, I would assume, he will slowly step out onto something resembling an Olympic diving platform. Below, the Earth bees the concrete bottom of a swimming pool that he wants to land on, but not too hard. Still, he39。t start planning... Those years, those days of do, finally, like youth, will end in our life. 此刻，天空是陰暗的，空氣里有著剛下過雨之后的清新因子。想要的，不想要的，界限明確，好像沒有什么可以撼動(dòng)自己。 Junior high school, thought to have a crush on just means that the real growth, but over the past three years later, his writing of alumni in peace, suddenly found that isn39。s governing body, has also ordered an immediate investigation into the referee39。t appealed against the disciplinary action your employer has taken against you. However, if you win your case, the tribunal may reduce any pensation awarded to you as a result of your failure to appeal. Remember that in most cases you must make an application to an employment tribunal within three months of the date when the event you are plaining about happened. If your application is received after this time limit, the tribunal will not usually accept i. If you are worried about how the time limits apply to you, take advice from one of the anisations listed under Further help. Employment tribunals are less formal than some other courts, but it is still a legal process and you will need to give evidence under an oath or affirmation. Most people find making a claim to an employment tribunal challenging. If you are thinking about making a claim to an employment tribunal, you should get help straight away from one of the anisations listed under Further help. If you are being represented by a solicitor at the tribunal, they may ask you to sign an agreement where you pay their fee out of your pensation if you win the case. This is known as a damagesbased agreement. In England and Wales, your solicitor can39。興趣是自發(fā)形成的，而默契是慢慢培養(yǎng)出來的。 ”這話一點(diǎn)也不假，回想當(dāng)初確定這個(gè)，還是挺茫然的。 通訊原理 當(dāng)程序開始時(shí)，初始化 VB 界面，打開通信端口，當(dāng)按下 VB 界面上的開始按鈕時(shí)，啟動(dòng)定時(shí)器，用于采集通信數(shù)據(jù)，該定時(shí)器每隔 采集一次通信數(shù)據(jù)；同時(shí)接收和發(fā)送函數(shù)也已經(jīng)打開，這時(shí)可以在 VB 界面中輸入南北、東西交通燈的運(yùn)行時(shí)間。 圖 配置 S7200CPU （ 2） 為 PLC 選擇站地址、波特率。并給出了該方法在十字路口交通燈實(shí)時(shí)監(jiān)控系統(tǒng)中的具體應(yīng)用。為此，我們考慮設(shè)計(jì)十字路口的監(jiān)控系統(tǒng)。 本設(shè)計(jì)采用順序控制指令進(jìn)行編程，具體程序如下： 網(wǎng)絡(luò)一：置位初始狀態(tài)。 流程圖 （ 1） 交通燈正常循環(huán)運(yùn)行邏輯流程圖 交通燈正常循環(huán)運(yùn)行邏輯流 程圖如圖 所示。 目前，普遍使用的傳送介質(zhì)有：同軸電纜、雙絞線、光纜，其他介質(zhì)如無線電、紅外微波等在 PLC 網(wǎng) 絡(luò)中應(yīng)用很少。 PC機(jī)的標(biāo)準(zhǔn)串口為 RS232。 通信系統(tǒng) 西門子 S7200 PLC 的通信功能較強(qiáng)，自由端口模式是計(jì)算機(jī)或其它帶有串行通信接口的設(shè)備與 S7200 CPU 之間通信的一種廉價(jià)和靈活的方法。 方案三：如果選用 CPU226 作為主機(jī)， CPU226 主機(jī)為 24 輸入 /16 輸出，與 4 輸入 /14輸出較為接近 。 表 輸入表 序號(hào) 輸入信號(hào)名稱 文字 符號(hào) 1 啟動(dòng)按鈕 SB1 2 停止按鈕 SB2 3 急車強(qiáng)通按鈕 1 SB3 4 急車強(qiáng)通按鈕 2 SB4 表 輸出表 序號(hào) 輸出信號(hào)名稱 文字 符號(hào) 1 南北左轉(zhuǎn)綠 HL2 2 南北左轉(zhuǎn)紅 HL13 3 東西左轉(zhuǎn)綠 HL16 4 東西左轉(zhuǎn)紅 HL6 5 南北直行綠 HL9 6 南北直行黃 HL14 7 南北直行紅 HL3 8 東西直行綠 HL4 9 東西直行黃 HL10 10 東西直行紅 HL7 11 南北人行綠 HL12 12 南北人行紅 HL5 13 東西人行綠 HL1 14 東西人行紅 HL8 8 根據(jù)表 和表 可以確定 PLC 以及 CPU 的選型。 (2)南北向和東西向人行道均設(shè)有通行綠燈和禁行紅燈。由于 PLC 本身具有通訊聯(lián)網(wǎng)功能，將同一條道路上的信號(hào)燈組成一局域網(wǎng)進(jìn)行統(tǒng)一調(diào)度管理，可縮短車輛通行等候時(shí)間，實(shí)現(xiàn)科學(xué)化管理。 梯形圖語言實(shí)際上是一種面向用戶的一種高級(jí)語言，可編程序控制器在執(zhí)行梯形圖的程序時(shí)，用解釋程序?qū)⑺?“ 翻譯 ” 成匯編語言后再 去執(zhí)行。 PLC 采取了一系列硬件和軟件抗干擾措施，具有很強(qiáng)的抗 干擾能力，平均無故障時(shí)間達(dá)到數(shù)萬小時(shí)以上，可以直接用于有強(qiáng)烈干擾的工業(yè)生產(chǎn)現(xiàn)場(chǎng)， PLC 已被廣大用戶公認(rèn)為最可靠的工業(yè)控制設(shè)備之一。與相同功能的繼電器相比，具有很高的性能價(jià)格比。這也是區(qū)別于其他一般微型控制系統(tǒng)的一個(gè)重要特征。 繼電器接觸控制 采用 繼電接觸式控制系統(tǒng) 設(shè)計(jì)交通燈控制系統(tǒng)， 主要由繼電器、接觸器、按鈕、行程開關(guān)等組成，其控制方式是斷續(xù)的，所以又稱為斷續(xù)控制系統(tǒng)。 交通燈監(jiān)控系統(tǒng)的設(shè)計(jì)意義 目前，我國城市十字路口的交通燈控制系統(tǒng)基本上都采用定時(shí)控制方式。 關(guān)鍵詞 ： 交通燈； PLC 控制系統(tǒng)；梯形圖 II 目錄 1 緒論 ........................................................................................................................................ 1 交通燈發(fā)展現(xiàn)狀 ............................................................................................................. 1 交通燈監(jiān)控系統(tǒng)的設(shè)計(jì)意義 ......................................................................................... 1 2 交通燈系統(tǒng)總體形式論證 ..................................................................................................... 2 繼電器接觸控制 ............................................................................................................. 2 可編程序控制器控制 ..................................................................................................... 2 3 系統(tǒng)硬件設(shè)計(jì) ......................................................................................................................... 5 系統(tǒng)的組成框圖 ............................................................................................................ 5 交通燈的控制過程 .......................................................