Programmable logic controllers (PLC) were originally introduced to replace large panels used for running automobile assembly lines. Controller flexibility allowed programming for year to year model changes and its capabilities has been extended to include mathematical functions, file manipulations, analog signal manipulations, and techniques for dealing with high speed signals. These added capabilities have allowed the application of programmable logic controller in many areas outside of traditional automobile assembly lines services e.g. continuous process control, high speed packing, energy distribution and automated warehousing. With the use of PLC the reliability, availability and mean time between failure increases. The use of PLC in complex system is highly justified.
Controller, Modicon, Microprocessor, Counters
