【正文】 es of Near East University. The kit is based on the popular PIC16F877 model microcontroller, manufactured by Microchip Inc. The overall cost of the kit is less than $200, which is well below the cost of similar mercially available educational temperature control kits. The design, modeling and digital control of the kit are described in detail. Temperature control kit Educational temperature control kits are not new. Many panies manufacturing laboratory kits also offer some kind of general process control or temperature control by Kuruganti is a temperature control loop trainer which is intended to show how the temperature in a heat exchanger can be controlled. TCL1, also by Kuruganti, is an on/offbased temperature control teaching kit. PROCON by Feedback Instruments is a progress control system, which includes rigs for level, flow, temperature and pH control. Here, the temperature control system uses water as the process fluid and the kid provide PID control with autotune facilities. G34/EV is a PIDbased educational temperature control unit manufactured by Elettronica. The unit can be interfaced to a PC and consists of a PID controller, power amplifier, and signal conditioner for temperature sensors. Near East University offers undergraduate and graduate level engineering courses and control engineering is one of these topics, which is taught for one semester. There are no practical experiments and students have been using the MATLAB package to design, simulate and test their control theory. It was felt necessary to provide some practical experiments to the students as a way of supporting the theoretical concepts taught in the classroom. The main reason to design a control kit rather than to buy a mercially available one was the cost. Process control is a very important field of automatic control engineering and as a first initiative it was decided to develop a digital temperature control experiment based upon a microcontroller. One of the aims during the implantation of this laboratory kit was to use low cost, but industrial equipment in order to ensure the necessary robustness for its use. It is hoped to develop more controlbased experiments in the near future with the participation of members of the faculty and students. The block diagram of the digital temperature control kit is shown in . The working principle of this experiment consists of heating the water in a small container using a lowvoltage electric heating element and a simple MOSFETbased power controller circuit. A temperature sensor is immersed into the water whose output signal is sent to a PICtype microcontroller. This signal is pared with a reference temperature signal and a PID controller algorithm is implemented by the microcontroller to achieve the required temperature control action. This process is used to teach the following important concepts to the students: 根據(jù)作者的經(jīng)驗(yàn)，當(dāng)學(xué)生們能夠親眼看到實(shí)驗(yàn)的各種現(xiàn)象時(shí)，他們會(huì)更好地學(xué)習(xí)工程課題。 Elettronica公司制造了 G34/EV，這 G34/EV是基于 PID 控制的教學(xué)溫度控制單元。加熱元件和傳感器浸入容器中。浮點(diǎn)算術(shù)的發(fā)展歷程是非常復(fù)雜的，它需要使用的是匯編語言，因此決定用高級(jí)語言來編寫微型控制器中的程序，這種語言同樣支持浮點(diǎn)算術(shù)。 T=M+S。該軟件包含了圖形選擇，它能夠繪畫出測量值的圖形。這種溫度控制器的另一優(yōu)點(diǎn)是它能夠讓學(xué)生自己動(dòng)手做實(shí)驗(yàn)和學(xué)習(xí)單片機(jī)，而單片機(jī)被廣泛應(yīng)用于智能電子控制項(xiàng)目中。使用 Zieglerichols 方法的一個(gè)優(yōu)點(diǎn)是會(huì)有一個(gè)非常滿意的回復(fù)并且?guī)缀醪粫?huì)出現(xiàn)錯(cuò)誤。為此，反饋循環(huán)是打開的，脈寬調(diào)節(jié)輸入一個(gè)脈沖與單片機(jī)啟動(dòng)加熱器是一致的。整個(gè)系統(tǒng)的簡單的數(shù)學(xué)模型會(huì)在這里進(jìn)行詳細(xì)地描述。傳感器的輸出端與微控制器中的 A/D 轉(zhuǎn)換器的一個(gè)輸入引腳相連接。這一實(shí)驗(yàn)的工作原理是在一個(gè)小容器里使用低壓電加熱元件和一個(gè)簡單的基于 MOSFET 的電源控制電路來加熱水。 溫度控制器 件 教學(xué)溫度控制器件現(xiàn)在已經(jīng)非常普遍。其中一些軟件包（像MATLAB 和 program CC）現(xiàn)在也已經(jīng)提供了較低花費(fèi)的版本，學(xué)生能都購買并且在自己的電腦上使用這些軟件，而不僅僅是在學(xué)校的實(shí)驗(yàn)室里。Modeling and identification of a real physical process Using the ZieglerNichols tuning method Using microcontrollers in process automation Developing and experimenting with digital PID controllers. Figure 2 shows a picture of the prototype experiment kit. The kit is rather simple, consisting of only low cost materials. A round plastic container is used to store the water. The heater element and the sensor are immersed in this container. The temperature is sensed using a low cost semiconductor sensor, which is protected inside a glass tube. The heating element is the type which is used in camping and other outdoor activities in order to warm up liquid in a cup, for example for making coffee. The heater operates with 12V, draws 10A of current and provides a power of 120W. A laboratory power supply to provide such high power is usually rather expensive so a standard 350W PC power supply is used instead, costing no more than ﹩ 50 .Using a low voltage in an experimental kit has the advantage that the system is safe as there is no risk of electric shock . Fig 2: The temperature control kit Figure 3 shows the electrical circuit diagram of the kit .The circuit is rather simple, consisting of only a few parts .LM35DZ is the analog semiconductor temperature sensor , PIC16F877 is the microcontroller ,and IRL1004 is a power MOSFET switch ,used to drive the heater element . The temperature sensor The temperature sensor used in the experiment is a 3pin semiconductor sensor with an output voltage directly proportional to the temperature. The output of the sensor is connected to one of the A/D converter inputs of the microcontroller. There was the opt