The HMI (man-machine interface) design, the need to achieve the goal, but is not a single command and feedback, but rather complex, mainly divided into four aspects: 

1. Play the machine itself should function. 

2. Improve the use of machine efficiency and performance. 

3. To ensure that the machines or systems in use are more economical and safe and extend the service cycle when they are user-friendly.

On the concept and function of the HMI:

HMI (Man-machine interface) is a covering multiple areas of science and technology, including the human body engineering, computer science, artificial intelligence, cognitive psychology, philosophy, sociology, anthropology, design, and engineering disciplines, so you can't entirely in the perspective of IT technology and research, even including the importance of cognitive psychology may be more important than computer science. HMI can also be called industrial tablets.

The simplest definition of the HMI is that between the human and the machine, through some interface, the human can give instructions to the machine, and the machine can return the execution status and system status to the user through this interface. In other words, the correct transmission of information and instructions between the human and machine is the main definition of the HMI.

In the design of HMI, the goal to be achieved is not a single command and feedback, but a complex one.

The concept of the HMI is mainly divided into four aspects:

1. Give play to the due function of the machine itself.

2. Improve the use of machine efficiency and performance.

3. Ensure that the machine or system in use is user friendly, Can be more economical and safe, prolong the use cycle.

4. Meet the physiological and psychological needs of users and improve their satisfaction.

Carefully reviewing the foregoing definitions and objectives, You can see that there's a lot of ambiguity between the two, If IT is a general IT technology, input and output are absolute, But there is no standard response mode between the user and the machine.

With the most important vision. The signal presented by the machine on the interface enables people to see the "that signal" correctly. But the viewer needs his own experience, knowledge, and surroundings to interpret the meaning of the message.

In other words, more sophisticated machines, without considering the demand of the user object, is often classified as a failure of the HMI, such as a computer engineering shows that much mathematical notation to just learn basic operations of young children use, the otherwise well-designed function is a barrier to interfere with the young children find the correct number, the results of its calculation speed is not as good as to young children a simple interface to the computer.

When the HMI touches the screen, the resistance and voltage on the resistance network change and the touch position is calculated by the software. 

The main functions of HMI are:

•    Data input and display;

•    Real-time information display of the operating status of the system or equipment;

•    Setting touch control on HMI can control the operation with HMI as the operation panel.

•    Alarm processing and printing.

In addition, the new generation of the industrial man-machine interface also has simple programming, the input of data processing, data login, and formula and other intelligent control functions. 

The original HMI is used to replace some buttons and some output show with, mainly cooperate with PLC to operate some actions, no control function, and now a lot of man-machine are script control function, using C or VB script even if there is no program in PLC can also let PLC according to your way of thinking action.

This simple truth is quite obvious in the above example. When the user's background and the machine's own function start to become complicated, the design of the HMI cannot only be conceived from the machine's function. But also from the perspective of the user.