What kinds of configuration and characteristics of PLC

Programmable Logic Controller (PLC) is essentially a kind of computer dedicated to industrial control. Its hardware structure is basically the same as that of a micro-computer.
(1) Power supply
The power supply of programmable logic controller plays an important role in the whole system. Without a good and reliable power supply system, it is impossible to work properly. Therefore, the manufacturers of programmable logic controllers also attach great importance to the design and manufacture of power supply. In general, the fluctuation of AC voltage is within the range of + 10% (+15%). PLC can be connected directly to AC network without taking other measures.
(2) Central Processing Unit (CPU)
Central processing unit (CPU) is the control center of programmable logic controller. It receives and stores user programs and data entered from the programmer according to the functions given by the programmable logic controller system program; checks the status of power supply, memory, I/O and alarm timer, and can diagnose grammatical errors in user programs. When the programmable logic controller is put into operation, it first receives the status and data of the input devices in the field by scanning, and stores them in the I/O image area, then reads the user program one by one from the user program memory. After the command is interpreted, the results of the logical or arithmetic operations performed according to the instructions are sent into the I/O image area or the data register. After all the user programs are executed, the output state or data in the output register of the I/O image area are transmitted to the corresponding output device, so that the cycle runs until it stops running. In order to further improve the reliability of programmable logic controllers, dual CPUs are used to form redundant systems for large-scale programmable logic controllers, or voting systems with three CPUs are used. In this way, even if a CPU fails, the whole system can still run normally.
storage
Storage of system software is called system program memory.
Storage of application software is called user program memory.
(4) I/O interface circuit
Field input interface circuit is composed of optical coupling circuit and input interface circuit of computer. It acts as input channel of interface between programmable logic controller and field control.
The field output interface circuit is composed of output data register, gated circuit and interrupt request circuit. The programmable logic controller can output corresponding control signals to the field executing parts through the field output interface circuit.
(5) Functional modules
Such as counting, positioning and other functional modules.
(6) Communication module