PLCs have their use in many areas, including basic relay control, motor control or motion control, industrial process control and complex networks. PLCs are often very expensive due to their ability to handle very complex process control, high speed and precision.
This project deals with an interesting way to achieve the sequential switching of loads in the repetitive nature of the work with the help of the micro controller 8051. It achieves a similar functionality to a PLC based on a micro-controller, where different loads are commuted according to the times Pre-programmed or the timings set during the execution time.
The main principle in the operation of the project are the timers and interruptions of the micro-controller.
For normal operation, the loads are switched sequentially according to the time set by the user. Internally, the timer 8051 is executed according to the time and once it reaches the set time, it automatically switches the load and resets the timer.
If the user wants to change the time intervals, he must press the button of configuration. This acts as an external interrupt to the micro-controller. Once the micro-controller receives the interrupt, the micro-controller turns off all loads and initialises the user input. With the help of two push-buttons, the desired time can be set.