Date Added: Jun 2012
Programmable Logic Controller (PLC) is a device that allows an Electro-Mechanical engineer to automate his mechanical process in an efficient manner. PLC is a typical Microprocessor or Micro-Controller based system with its dedicated operating system to interpret the control specification, scan inputs and accordingly activate the final control elements. As the number of rungs of the ladder diagram increases or the control specification logic becomes more complex, the time taken by the PLC also increases. This results in failure to respond during safety critical situation. This happens because: in conventional PLC's, the control specifications are first converted into intermediate instruction list and then this intermediate list of instructions is converted into op-codes that are compatible with processing core inside PLC.