PLC Logics and HMI Screens for Advanced Real Time Clock Automation: A pratical approach to occupancy and watering schedule using IEC 61131 - 3 Ladder Logic (AUTOMATION RECIPES)

This booklet is the fourth of a series dedicated to automation recipes created with the PLC (Programmable Logic Controller) and HMI (Human Machine Interface) binomial. The series is aimed at an audience of readers with an elementary knowledge of PLC programming, eager to learn advanced solutions, extensively tested on real systems. In modern computer programming, generally oriented to the development of "object-oriented" software, the developer strives, as much as possible, to resort to so-called "Design Patterns", standard solutions for frequently recurring problems. A design pattern describes a problem, particularly recurring in a given context, and then provide the heart of the solution to this problem. It is therefore possible to successfully reuse this solution, thousands and thousands of times, with the certainty of using an efficient and well-tested solution. In the present series, which deals exclusively with development on PLC-HMI, the term "design pattern" has been replaced by the term "automation recipe" for an easier understanding by the non IT reader. This fourth notebook deals exhaustively with management strategies based on the internal calendar clock of the PLC. The latter, in fact, allows you to easily generate triggers in coincidence of time intervals corresponding to every minute, every 5 minutes, every quarter of an hour, every hour, every day, every month, every year. These triggers are made available to other application program routines in order to schedule totalization or reporting activities on an hourly, daily, monthly and yearly basis. The system variable "day of the week" also allows you to manage differentiated control logics, depending on whether the day in question is between the working days from Monday to Friday, or Saturday rather than Sunday. Within the day, differentiated time intervals can be configured. This possibility is very important for smart electricity management systems in multi-hour tariffs. Occupation tables are typically used to manage the start / stop of air conditioning systems in the residential building sector. Extending the concept of the occupancy schedule it is possible to use the same logic for starting / stopping of the refrigeration system at times of particular loading / unloading of product in the cold rooms. Likewise, this type of logic can also be used to manage the duration and frequency of watering both within the day and the week. This type of recipe therefore has a general use, somehow "transversal" to the various types of technological systems. We can conclude that any type of management and accounting of both electric and thermal energies can not do without the temporal triggers offered by the RTC (Real Time Clock) subroutine. In detail, the first section of this notebook, dedicated to the application domain, illustrates the date clock and the employment or watering tables. The second section deals with the development of combined software for both PLC and HMI. The logic of the RTC (Real Time Clock) subroutine and that of the functional blocks (UDFB), TimeValidator, Load1Enable, Load3Enable, DayOfWeekValidator and Watering are illustrated, along with the relative display screens, local monitoring and configuration parameter settings. Finally, the third chapter shows the application of the concepts developed in a real case of control of an irrigation system. All the logics, published in the book, have been developed using the IEC61131-3 compliant Ladder language; therefore it is extremely easy to migrate them on almost all the PLCs of other manufacturers. The same applies to HMI screens whose graphic controls are very similar on the different equipment offered on the market. The reader who already has experience with other manufacturers' equipment can therefore continue to use what he knows best.

這本小冊子是一系列專注於使用可程式邏輯控制器（PLC）和人機介面（HMI）的自動化配方的第四本。該系列針對具有基本PLC編程知識且渴望學習在實際系統上廣泛測試的高級解決方案的讀者群體。在現代計算機編程中，通常面向開發“面向對象”軟件的開發人員會盡可能地使用所謂的“設計模式”，這是一種常見問題的標準解決方案。設計模式描述了一個在特定上下文中特別常見的問題，然後提供了解決這個問題的核心。因此，可以成功重複使用這個解決方案，並且可以確保使用一個高效且經過充分測試的解決方案。在本系列中，專注於PLC-HMI開發的術語“設計模式”已被替換為“自動化配方”，以便非IT讀者更容易理解。這本第四本筆記詳細介紹了基於PLC內部日曆時鐘的管理策略。實際上，後者可以輕鬆生成與每分鐘、每5分鐘、每15分鐘、每小時、每天、每月、每年相對應的時間間隔重疊的觸發器。這些觸發器可供其他應用程序例程使用，以便按小時、每天、每月和每年的基礎安排總計或報告活動。系統變量“星期幾”還可以根據該日是否在周一至周五的工作日之間，或者在周六而不是周日之間，來管理不同的控制邏輯。在一天內，可以配置不同的時間間隔。對於多時段電力管理系統在住宅建築領域中，這種可能性非常重要，用於管理空調系統的啟動/停止。擴展佔用時間表的概念，可以使用相同的邏輯在冷庫中的特定負載/卸載時間啟動/停止冷凍系統。同樣，這種邏輯也可以用於管理每天和每週的澆水持續時間和頻率。這種類型的配方因此具有一般用途，對於各種技術系統來說都是“橫向”的。我們可以得出結論，無論是電能還是熱能的任何管理和計量都無法在RTC（實時時鐘）子程序提供的時間觸發器的幫助下進行。具體而言，本筆記的第一部分專注於應用領域，介紹了日期時鐘和佔用或澆水時間表。第二部分介紹了同時針對PLC和HMI開發的結合軟件。介紹了RTC（實時時鐘）子程序和功能塊（UDFB）TimeValidator、Load1Enable、Load3Enable、DayOfWeekValidator和Watering的邏輯，以及相關的顯示屏、本地監控和配置參數設置。最後，第三章展示了在灌溉系統控制的實際案例中應用所開發概念。書中發表的所有邏輯都是使用符合IEC61131-3的梯形語言開發的，因此非常容易將它們遷移到其他制造商的幾乎所有PLC上。對於HMI屏幕，其圖形控件在市場上提供的不同設備上非常相似，因此對於已經有其他制造商設備經驗的讀者來說，可以繼續使用他們最熟悉的設備。