Programmable Logic Controller | GIC India
Most industrial controllers, such as programmable logic controllers (PLCs) and programmable automation controllers (PACs), can handle essential functions like real-time control of discrete and analogue input/output (I/O) connections. This type of functionality is a given with most controllers, with the main concern being the capacity to handle the required number of I/O points, which is usually easy to ascertain.
When defining industrial controllers, concerns often apply to other abilities such as data handling, communications, and high-speed control. Identifying functions required to select and implement controllers and knowledge of how features improve designs can help. PLC Hardware 1 to 5: Input Module: Inputs are data given to PLC, classified in Digital IP: Switch, Push Button, Proximity Sensors, etc which gives input of either 1 or 0 to PLC Analog IP: Every analogue sensor like Temperature, weight, distance, etc which gives analogue data to PLC Output Module: Output from PLC, classified in Digital op: output signal either 1 or 0 Analog op: the variable output of 0 to 12 VDC or 4mA to 20mA DC. CPU: This component act as the brain of the system. CPU consist of Arithmetic Logic Unit, Program memory, Process image memory, Internal timers and counters, flags It receives information from the I/P device, makes decisions depending upon the information and logic written and sends information through the O/P devices. Power Supply: Certain PLCs have an isolated power supply. But, most of the PLCs work at 220VAC or 24VDC. Memory: Stores the information about the status of input and output devices, and the values of timers, counters, and other internal devices. Programming Device (Computer): This device is used to feed the program (logic) into the memory of the plc. First, we make a program in certain PLC software then we download it to PLC. PLC Programming: It is a logic we make in Computer in PLC software. Based on that logic & conditions PLC gives output. Most commonly used programming language is Ladder diagram (LD) also known as Ladder logic Typical Ladder logic: Here the input is push-button & output is light, so when PB is pressed due to the logic of PLC light will be turned ON.
Typical PLC
Programmable Logic Controller can be used in almost all industrial application solutions right from small machines to large manufacturing plants. Even it caters applications of redundant systems at critical process plants.
Advantages of PLC:
They are fast and designed for the rugged industrial environment.Easy to change logic i.e. flexibilityLow power consumptionThey are attractive to Cost-Per-Point Basis.Analog signal handling and closed-loop control programmingReliable due to the absence of moving partsEasy to couple with the process computersCounter, timer and comparator can be programmedCapable of handling very complicated logic operationsFlexibility: One single PLC can easily run many machines.











