What is the difference between HMI and PLC?

Difference: HMI (Human Machine Interface) is an intelligent operation control and display device; when the screen is touched, the resistance and voltage on the resistor network change and the touch position is calculated by the software. The PLC is a digital computing controller with a microprocessor for automatic control, which can load control instructions into the memory at any time for storage and execution.

HMI

Human Machine Interface (HMI), also known as touch screen monitor, is a An intelligent operation control and display device. When the screen is touched, the resistance and voltage on the resistor network change and the touch position is calculated by the software.

Human-machine interface (HMI) is also called "human-machine interface". Its main function is to help people and computers establish connections and exchange information. The interface of input/output devices, these devices include keyboards , monitor, printer, mouse, etc.

PLC

Programmable Logic Controller (PLC), a digital computing controller with a microprocessor for automation control, can Control instructions are loaded into memory at any time for storage and execution.

PLC is composed of functional units such as CPU, instruction and data memory, input/output interface, power supply, and digital-to-analog conversion.

There are many communication methods between HMI and PLC, the most common of which are Ethernet and serial port.

What is the relationship between HMI and PLC?

They are actually "dead enemies". HMI is the "villain" and PLC is the "good old man".

Because the PLC painstakingly converts the information collected on-site [captured through on-site sensors and converted into signals identifiable by the PLC, such as 4~20mA current signals], to calculate the results.

HMI transmits all these data from the communication port of the PLC through the data cable [Ethernet or serial port data cable]. Also, the HMI has to command the PLC to do this and that.

In addition, the glamorous side is completely taken up by HMI [process control and display], and the PLC has to stay pitifully in a dark box [control cabinet] without seeing the light.

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