PROGRAMMABLE LOGIC CONTROLLER
PLC is a device that controls machines and industrial processes
MAIN PARTS
Power supply
CPU
I/O section
PROGRAM SYSTEM
I/O devices
Digital
Analogue
it is an electronic controller
it is designed for industrial environments
Provides electricity to the device
it is an electronic processor
connects a physical device to the PLC
It scans inputs, executes logic operation and updates outputs
Devices can be digital or analogue
Provide a signal (on or off) to CPU or to an external device
It follows ONLY a program
It does it during a cycle called "scan time"
CPU memory stores the program and controls the I/O variables
Using electrical symbols create the program
Programs are created with "Ladder logic"
they represent the logic connection between the components
Convert a voltage or a current into a digital value and vice versa.
The digital value is sent to CPU or any other device