Probably the best way to introduce a PLC to someone is to show them something it can do. This particular example is only one of millions of possible applications for the programmable logic controller which is basically a box that can be programmed to carry out particular functions for a machine/process automatically. It can also be programmed to monitor set points or events to either adjust to the condition (the logic must be programmed for this) or to set of some form of alarm. The PLC belongs to the world of automation but it is most definitely a Smart idea and PLC manufacturers round the world are continually developing more advanced programmable logic control for industries and individuals and even for advanced robots too. The following presentation is a brief insight into PLC machine control in a conveyor system with a shuttle press. Notice the black box (PLC) on the top right hand corner is controlling the process.


The supply of PLC units, programming and consulting with industry is a business in it's own right.  Engineers and Technicians have been fabricating PLC control panels, relays and monitoring/control systems for many decades although most of the general public may not be fully aware of their presence since this kind of work will normally be carried out by contractors who often install them in control panels which are locked. The following presentation is an example of an active PLC specialist company which can give us a better idea of what a PLC installation looks like in an industrial setting.


PLC programming might require some training either individually or in schools which specialize in ladder logic. The PLC programming skills will enable individuals to custom program a PLC to turn devices on or off at set times or control something due to changing input data to the PLC.  Special controls functions can be implemented in a logical sequence and even combined with an internal calculation that will determine the next logical step or what is displayed on a screen or communicated elsewhere. The following media presentation is focusing on a standard industrial application involving level control of a fluid in a tank. Anyone attempting to write the program will need to firstly understand the logical sequence of events and then using their PLC skills and experience to program something that will automate a process for an end user. There are many examples of PLC control and the PLC might not only be controlling but also acting as an Annunciator that can respond to "First Out" situations for e.g and respond accordingly when a "first event" alarm occurs that needs to be monitored by operators in the event of an abnormal situation. This example we are using is of course not fully explanatory but simply to show that PLC programming can become very involved depending on the complexity of the process and the safety and redundancy levels required by the client. An expert in building logical flow diagrams might enjoy PLC programming.