What are the components of the internal structure of PLC?
Today, I will tell you about the internal structure of PLC? The structure of PLC and the role of each part.
The structure of PLC and the functions and functions of each part
1. Host
The host segment includes the central processing unit (CPU), system program memory, and user program and data memory
The CPU is the core of the PLC, and all logical operations and judgments are completed by it, and all other components are controlled. It is what we often call a computer chip.
(1) Run the user program.
(2) Monitor input/output interface status.
(3) Making logical judgments and conducting data processing
There are two types of internal memory: one is system program memory, and the other is user program and data memory
System program memory: mainly stores system management and monitoring programs and programs that compile and process user programs. The system program has been fixed by the manufacturer and cannot be changed by the user.
User program and data storage: mainly stores user-compiled applications and various temporary data and intermediate results.
2. Input/output (I/O) interface
Input interface is used to receive control signals from input devices such as buttons, stroke switches, sensors, etc.
The output interface is used to drive the output device (such as contactors, solenoid valves, indicator lights, etc.) through the output circuit through the output circuit.
3. Power supply
Power supply refers to the DC switching regulated power supply equipped for the operation of internal electronic circuits such as CPU, memory, and I/O interface
4. Programmer
The programmer is an important external device of the PLC, which is mainly composed of a keyboard and a display. Programmers are divided into two types: simple and intelligent.
Small PLCs commonly used simple programmers, large and medium-sized PLCs multi-purpose intelligent programmers. The role of the programmer is to program the user and feed it into the PLC program memory.
The programmer allows you to check, modify, debug user programs and monitor PLC operating conditions online. Many PLCs are now connected to computers and programmed or monitored using dedicated tool software.
5. Input and output expansion interface
I/O expansion interface is used to connect the expansion unit to the base unit (i.e. the host).
6. External device interface
This interface connects external devices such as programmers, printers, barcode scanners, etc. to the host computer.