A programmable logic controller (PLC) is a microprocessor-based computer  unit that can perform control functions of many types and varying  levels of complexity. PLCs are designed to be easy and flexible to work  with. The first commercial PLC system was developed in the early 1970s  to replace hardwired relay controls used in large manufacturing assembly  plants. The initial use of PLCs covered automotive assembly lines, jet  engines, and large chemical plants. PLCs are used today in many tasks  including robotics, conveyor systems, manufacturing control, process  control, electrical power plants, wastewater treatment, and security  applications. 

• Explain what a programmable logic controller (PLC) is and discuss its advantages over relay systems.
• Identify the main system components of a PLC and that of a PC.
• You  may not realize that PLCs are everywhere making daily activities/tasks  easier by automation. Look for PLCs in your daily life (industry  automation, home automation, etc.). Compare and contrast a PLC and  general-purpose computer in relation to your daily life. For example,  including how and where PLCs improve or impact your life.