Reference : Siemens Basics of Plc
a PLC can do complex tasks, replacing wiring between devices and relays by PLC
program.Modifying the application and correcting errors are easier . program in
a PLC easy to create and change .
Automation technologies such as " PLC - SCADA Systems - DCS Systems - Industrial Application using Robots - Power System Protection - Power System Distribution And CNC Applications " and other control systems