Industrial computers called Programmable Logic Controllers (PLCs) are used to monitor and manage industrial equipment based on customised programming. PLCs include a variety of inputs and outputs. 

Programmable Logic Controller are available in a wide range of sizes and form factors. Some can fit in your pocket, while others are so big they need to be mounted on their own sturdy racks. Some PLCs are more modular, having only basic I/O (Inputs and Outputs), but they may be tailored to match various industrial applications by adding more back planes and functional modules (such analogue I/O, communications modules, or display modules).

Input Scan: During the input scan, the PLC reads the state of the input devices connected to the I/O modules. The I/O modules convert the physical signals from the input devices (such as voltage, current, or resistance) into digital signals that can be processed by the CPU. The input data is stored in memory and is used by the program during the next step.

During program execution, the Programmable Logic Controller executes the program stored in memory based on the input data read during the input scan. The program consists of a series of instructions that manipulate the input data and control the output devices.

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