【正文】 ： 圖書通過光電管，光電管閉合與斷開。當(dāng) C1當(dāng)前值大于等于預(yù)設(shè)值 PV時（此設(shè)計中， PV值為 10本），計數(shù)器位 C1置位。即定時器當(dāng)前數(shù)值定位 0 北京郵電大學(xué)世紀(jì)學(xué)院畢業(yè)設(shè)計（論文） 25 程序解釋 此程序是在圖書通過匯合申機后計數(shù)，達(dá)一定數(shù)量 (10 本 )后，滿箱處理，定時器開， 5s 鐘后 恢復(fù)初始狀態(tài)，如此循環(huán)。 基本達(dá)到設(shè)計要求的功能，即對 圖書 進(jìn)行分揀。在整個論文工作即將結(jié)束之際，在此向?qū)煴硎疚易钫嬲\的感 酬 !同時特別感謝李冠群老師 ,宮香山老師在論文方面提出寶貴意見，感謝導(dǎo)師們在畢業(yè)設(shè)計期間給予的理論指導(dǎo)和建議。當(dāng) 然 ，您所 在公司的 規(guī) 程和您在 培訓(xùn) 中接 受 的 實踐 經(jīng) 驗 是 必須 遵 循 的。包括下列 主題 ： I/O 點 、操作的功能描述、在允許 每 個 執(zhí) 行 器 (例如 螺 線管、電 機 和 驅(qū) 動 器 )動作 之 前必須達(dá) 到 的狀態(tài)、關(guān)于操作員 界 面 的描述以及與 過 程或 機器 其 他 部 分相 連的任 何 接 口 的描述。在設(shè) 計 安全電路 時 ，應(yīng) 考 慮 以下 幾 點 ： _ 識 別 有可能不合適或者不可預(yù) 料 操作有可能 會造 成危害的 執(zhí) 行 機 構(gòu)。 _ 設(shè) 計 獨立 于 CPU 的手動或 機 電 超 馳 控制 來 阻止 危險的操作。包括如下內(nèi)容： _ 與 過 程或者 機器 有關(guān)的 每 個操作員 站 的 位 置 總 圖 ?？梢詥⒂妹總€模擬量輸入通道北京郵電大學(xué)世紀(jì)學(xué)院畢業(yè)設(shè)計（論文） 28 的濾波功能。 在每次掃描期間， CPU224XP 的 AIW0 和 AIW2 模擬量輸入都會讀取模 數(shù)轉(zhuǎn)換器生成的最新值，從而 完成刷新。 如果信號變化很快，不應(yīng)該選用模擬量濾波。在程序或中斷程序的執(zhí)行過程中，立即 I/O 指令允許您直接訪問輸入與輸出。 如果在程序中使 用了中斷，與中斷事件相關(guān)的中斷程序就作為程序的一部分被存儲。有關(guān)局部存儲器的更多信息，請參見本章中的 局部存儲區(qū)： L。 Guidelines for Designing a Micro PLC System 北京郵電大學(xué)世紀(jì)學(xué)院畢業(yè)設(shè)計（論文） 29 There are many methods for designing a Micro PLC system. The following general guidelines can apply to many design projects. Of course, you must follow the directives of your own pany’s procedures and the accepted practices of your own training and location. Partition Your Process or Machine Divide your process or machine into sections that have a level of independence from each other. These partitions determine the boundaries between controllers and influence the functional description specifications and the assignment of resources. Create the Functional Specifications Write the descriptions of operation for each section of the process or machine. Include the following topics: I/O points, functional description of the operation, states that must be achieved before allowing action for each actuator (such as solenoids, motors, and drives), description of the operator interface, and any interfaces with other sections of the process or machine. Design the Safety Circuits Identify equipment requiring hardwired logic for safety. Control devices can fail in an unsafe manner, producing unexpected startup or change in the operation of machinery. Where unexpected or incorrect operation of the machinery could result in physical injury to people or significant property damage, consideration should be given to the use of electromechanical overrides which operate independently of the S7200 to prevent unsafe operations. The following tasks should be included in the design of safety circuits: Identify improper or unexpected operation of actuators that could be hazardous. Identify the conditions that would assure the operation is not hazardous, and determine how to detect these conditions independently of the S7200. Identify how the S7200 CPU and I/O affect the process when power is applied and removed, and when errors are detected. This information should only be used for designing for the normal and expected abnormal operation, and should not be relied on for safety purposes. 北京郵電大學(xué)世紀(jì)學(xué)院畢業(yè)設(shè)計（論文） 30 Design manual or electromechanical safety overrides that block the hazardous operation independent of the S7200. Provide appropriate status information from the independent circuits to the S7200 so that the program and any operator interfaces have necessary information. Identify any other safetyrelated requirements for safe operation of the process. Specify the Operator Stations Based on the requirements of the functional specifications, create drawings of the operator stations. Include the following items: Overview showing the location of each operator station in relation to the process or machine Mechanical layout of the devices, such as display, switches, and lights, for the operator station Electrical drawings with the associated I/O of the S7200 CPU or expansion module Digital inputs: Each scan cycle begins by reading the current value of the digital inputs and then writing these values to the processimage input register. Analog inputs: The S7200 does not update analog inputs from expansion modules as part of the normal scan cycle unless filtering of analog inputs is enabled. An analog filter is provided to allow you to have a more stable signal. You can enable the analog filter for each analog input point. When analog input filtering is enabled for an analog input, the S7200 updates that analog input once per scan cycle, performs the filtering function, and stores the filtered value internally. The filtered value is then supplied each time your program accesses the analog input. When analog filtering is not enabled, the S7200 reads the value of the analog input from expansion modules each time your program accesses the analog input. Analog inputs AIW0 and AIW2 included on the CPU 224XP are updated every scan with the most recent result from the analogtodigital converter. This conv