PLC PROGRAMMING USING SIEMENS
A PLC operates through a continuous, four-step scan cycle that ensures rapid and predictable responses to changes on a factory floor.
Read inputs: The PLC checks the status of all its connected input devices, such as sensors, switches, and pushbuttons.
Execute logic: Based on the program loaded into its memory, the PLC uses the input data to process the control logic and determine the necessary output commands.
Write outputs: The PLC sends signals to all its connected output devices, including motors, valves, indicator lights, and actuators.
Housekeeping: The PLC performs internal diagnostics and communications tasks before repeating the cycle.
A Siemens PLC operates as the central control unit for an industrial process. The hardware components include: Power Supply: Provides power to the system. CPU: The central processing unit that executes the control program. Input/Output (I/O) Modules: Connect to sensors, switches, and other field devices to read inputs and control outputs. Communication Modules: Enable communication with other PLCs, human-machine interfaces (HMIs), and other network devices. The software, running on the CPU, processes signals from input devices and controls the output devices based on the programmed logic.