What is PLC and How it helps industry automation ?
The full name of the PLC is Programmable Logic Controller and it is a computer that helps in automating the industries. You can understand it by its name also as Programmable means ability of re-programming , Logic means set of instructions that are written with the help of software and last word is Controller means – Hardware device that provides the structure so that we get the required output from. PLC normally takes the input signal from the input device and process it by CPU module then provide a output signal.
When plc generates a output signal then we can operate the different types of output devices like lamps, solenoids, motor, etc. Output signal will depend upon the wiring of the plc because there are two methods are available as PNP & NPN.
How PLC transmits a signal by taking a input signal ?
PLC transmits a signal by opto-coupler( emitter led and receiver)
- Input Signal: PLC CPU sends a low-voltage DC signal.
- Internal LED: This signal flows into a small internal LED, turning it on.
- Optical Transmission: The LED emits infrared light which travels across a tiny, transparent insulating barrier inside the IC package.
- Photo-sensitive Device: On the output side of the barrier, a photosensitive component (e.g., a phototransistor, photodiode, or photo-triac) detects the light.
- Output Activation: The light causes the phototransistor to turn ON, allowing the 24V field current to pass through and energize the external device.