The concept of controlling system is a very simple and easy task. It involves a systematic approach by following the operation procedure.
1. Determine the Machine sequence of operation
You have to decide what equipment or system you want to control. The ultimate purpose of the programmable controller is to control an external system. This system to be controlled can be machine equipment, or process and is often generically called the controlled system.
2. Assignment of inputs and outputs
All external input and output devices to be connected to the programmable controllers must be determined. The input devices are the various switches, senses etc. the output devices are the solenoids, electromagnetic valves, motor, inductors etc.
3. Writing of the program
Write the Ladder Diagram program by following the control system sequence of operation as determined by step one.
4. Programming into memory
You can apply power to the programmable controller. Depending on the type of programmable controller, you may have to do an I/O generation to prepare the system configuration. After that, you can enter your program in the memory either by programming console or by computer aided ladder software tool. After completion of the programming, you should check for any coding errors by means of diagnostic function, and if possible simulate the whole operation to see that it is alright.
5. Running the system
Before the start push button is pressed, thoroughly ensure that the input and output wiring are correctly connected according to the I/O assignment. Once confirmed, the actual operation of the PLC can now be started. You may need to debug along the way and fine tune the control system if necessary. Test run thoroughly until it is safe to operate by anyone.