Hi am Doi i would like to get details on ladder circuit diagram of school bell system using plc ..We're having a project about plc. I need help on how to build a ladder diagram of school bell with announcement system. I'm an Electrical Engineering student, studying at BISU-MC..


thank you

The project is designed to automatically operate an electric bell several times as required in an educational institution like school or college. It overcomes the difficulties of switching the bell on/off manually. This proposed system has an inbuilt real time clock (RTC) to keep a track of the time and thus to switch on/off the load accordingly.

The project uses a real time clock (RTC DS1307) interfaced with the microcontroller of the 8051 family. While the set time equals to the real time, the microcontroller gives command to the corresponding relay to turn on the bell, and then, another command to switch off the bell as per the program.

Multiple on /off time entries is the biggest advantage with this project. A matrix keypad is used for entering time. A 7-sement display is interfaced with the microcontroller to display time.

Furthermore, this project can be enhanced by interfacing a GSM modem to the existing project so that the bell ringing system can be controlled by sending an SMS to the control unit.