PLC (PROGRAMMABLE LOGIC CONTROLLER)

Programmable Logic Controller (PLC)

Words Programmable Logic Controller or PLC which is often abbreviated as we often see the last few years. At first, this tool is used to replace the relay-based control systems are inflexible and expensive.

Definition PLC
Based on the name, the concept Programmable Logic Controller is as follows:

1. Programmable
Showing ability in terms of memory to store programs that have been created that can easily be altered function or usefulness.

2. Logic
Demonstrated the ability to process input arithmetic and logic (ALU), which perform operations compare, add, multiply, divide, subtract, negation, AND, OR, and so forth.

3. Controller
Demonstrated the ability to control and regulate the process so as to produce the desired output.

According to the National Electrical Manufacturing Association, the 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 industrial processes in accordance with desired. PLC is able to do a continuous process input variables and provide appropriate decision making programming as desired output values under control

According forumsains.com, PLC is a "special computer" for applications in industry, to monitor the process, and to replace the hard wiring control and has its own programming language. However, different PLC with computers because it is designed for installation and maintenance by technicians and electricians in the industry that does not have to have a high electronics capabilities and provides flexible control based on the instruction execution logic.

According Capiel (1982), PLC is an electronic system that operates digitally and is designed for use in industrial environments, where the system uses a programmable memory for storage internally instructions to implement specific functions such as logic, sequence, timing , counting and arithmetic operations to control machines or processes through modules I / O digital and analog.

Function PLC
Functionality and usability of the PLC can be said to be almost unlimited. But in practice it can be divided in general and specific. In general, the function of the PLC is as follows:

1. Kontrol Sekuensial
Processing the input signal into a binary output that is used for the processing of engineering sequentially (sequential), here PLC keep all step / sequential steps in the process in the proper order.

2. Plant monitoring
Monitoring a system (eg, temperature, pressure, altitude level) and take the necessary action in connection with the controlled process (eg, the value has exceeded the limit) or display the message to the operator.

In particular, the PLC has the function as an input provider (input) to CNC (Computerized Numerical Control) for purposes of further processing. CNC has a higher accuracy and more expensive when compared with the PLC. This device, usually used for the finishing process, forming the workpiece, molding and so on.

Deficiency PLC