This E book provides both fundamental and cutting-edge coverage on PLCs. It explains most basic to intermediate and advance instruction through many worked-out examples and explanations of the solutions. Since this is a self-teach manual, it is assumed that reader may not have any access to a PLC or instructor, to discuss any problems. Based on this assumption, the reader is familiarized with S7-200 Micro/Win software (Developed by Siemens Automation) to show the reader how the software could be used to edit, run and finally how to debug a program in hand. So, this is not just another programming book in PLCs. Two links are given in this EBook to download a simulator, and HMI editor. Both of these are going to be free software.