PLC (Programmable Logic Controller) was first introduced in 1969 by Richard E. Morley is the founder of Modicon Corporation. According to the National Electrical Manufacturing Association (NEMA) PLC is defined as a digital electronic device with a programmable memory for storing instructions that execute specific functions such as logic, sequence, timing, counting, and arithmetic to control an industrial machine or process accordance with the desired industry. PLC is able to do a continuous process according to the input variables and provides the programming decisions at will so that the output under control.
PLC is a “special computers” for applications in industry, to monitor the process, and to replace hard wiring and control has its own programming language.
However, PLC is not the same as the PLC will personal computer designed for installation and maintenance by technicians and experts in the electricity industry does not have to have a high electronics skill and providing flexibility based on the instruction execution control logic. That’s why PLC is increasingly growing in terms of both number of input and output, the amount of available memory, speed, communication between the PLC and how or programming techniques. Almost all kinds of production processes in industry can be automated by using a PLC. Speed and accuracy of operations could be improved much better use of this control system.
The advantages of the PLC is its ability to transform and replicate the process at the same operation with communication and information-gathering vital information.
Operations on the PLC consists of four parts:
1. observation of the input
2. running the program
3. output value
Of the excess over the PLC also has shortcomings, among others, are often highlighted is that it takes to program a PLC expert and someone who understands what is required by the plant and understand the security or safety to be met.
Meanwhile, a trained person like that is quite rare and the programming must be made directly to the place where the servers are connected to the PLC, while it is not uncommon where the computer was playing in dangerous places. Therefore we need a device that is able to observe, edit and run programs remotely.