My view on PLC

hello friends..
In this post i will share my views on plc's.Plc means programmable logical controllers.They are widely used in industry for automation.Plc basically contains a dsp chip as a main controller.This plc should be programmed according to our requirement by the software provided by the manufacturer of that particular plc.Almost every plc will have a separate programming software which will be different to others.But the basic instructions will remain same.Mainly the complex instructions will be more distinct with one another.The Siemens, GEFanuc and Allen Bradley plc are used mostly all over the world.Theses plc's are very robust and rugged compared to other manufacturers.Basically a plc is more rugged in nature compare to the controllers.The controller boards are not mush rugged to the harsh industrial environment.The ic's in a controller board will not operate for a long time due to some reasons.That to programming a controller is much tough and time consuming process compared to programming a plc.Because the plc programmable software which will be provided by the manufacturer is so easy to program.Only the programmer should know the basic instructions and the basic functions of that particular plc to program a plc.Where as for programming a controller he should know about the archithure of the controller and all the pin configuration about the particular controller.Basically the plc also contains a dsp processor which is also a controller.But in plc the dsp processor will be programmed using a separate software which will be the front end for the user.In the back end the program which is programmed by using the software provided by the manufacturer is converted to assembly language program by using some compilers which will not be visible to the user.Also the circuit for a plc is designed more carefully such that it should have noise immunity,less power dissipation etc...Usually the plc will be having an input and output isolation so that what ever happened in the output of the plc will not effect the input.The plc should have a proper quality certification for entry in the market.Usually people will make controller boards by them only for a special purpose,but plc's are made for as common for many processes.Also the PLC's will have proper colling and noise resistance property.Now a days the every plc manufacturers are coming up with scada software along with the plc.By using scada the user can monitor all the inputs and outputs in the plc.So suppose an input fails he can immediately replace it with a new one with out troubleshooting.The man machine interface will be more with scada.scad provides a GUI for the events running in a particular machine.At the start the user need to program the scada an plc according to his purpose and requirement.Ones he programed it can be used through out its life.Mostly the plc s used will work continuously for many years with any problems.Now a days every industry is prefer scada , because the user can monitor the operations of the
machine by sitting in a common room which contains all the information about the machines.All the machines in an industry can be connected to a common source and can be acceded from any where of the world by using scada.It is basically a piece of software just resembles a networking software.The machine's connected with scada can be resembles with a group of computers connected in a network.In network the server has all rights to view any location in its client.Same way the scada software also works.But the plc should be compatible with scada.Now a days all most every manufacturer of scada are proving their software which will be compatible for different plcs.Because of this scada a single person can control all the machines inside a big industry.
OK friends that's for now..have nice day..