Why PLC’s are preferred over Micro-controllers

The PLC is said as an Industrial Digital Computer designed for industrial usage like controlling processes or machinery. It contains various types of I/Os that are very suitably matching with the industrial instrumentation.It provides the flexibility in the programming using the “ladder language” that is similar to industrial standard “ladder Network” used for designing automatic control schemes in the plants. The overall system is of both modular and compact type enabling the user to add modules accordingly to increase the I/Os. It has the standard programming interface along with the online monitoring features.

Micro-controller is a microprocessor which can be used for specific and limited type of application.A micro controller contains one or more CPUs along with memory and programmable input/output peripherals.It has less programming memory, available as a single chip solution for smaller applications. PLC internally uses a micro controller to handle all inputs,outputs & logical scans. Micro controllers are cores which is not easy as PLC to be programmed. PLC works with power and Micro-controller works with electronic i.e. PLC works with relays while Micro-controller works with transistors (even it may work with electronic relays). Usually the Micro controller doesn’t work as a stand alone controller but it come as a part of electronic circuit or device while the PLC is a stand alone controlling device that I can program it for any process accordingly.From among all the differences the major difference between a PLC and a  micro controller is that PLC works on both ac and dc with high voltages while micro controller works on low voltage dc system so that’s the reason why PLC’s are used in big industries instead of micro controller.