Currently, PLCs occupy a significant position in industrial automation. Continuous technological advancements have greatly promoted the improvement of PLC-based control systems in terms of control functions and control levels. Simultaneously, the requirements for control methods, operational levels, and intuitive, personalized operation performance are also increasing. Therefore, interactive operation interfaces, alarm logging, and printing have become important aspects of the entire control system. This is especially crucial for industrial control systems with complex processes and numerous control parameters. Thus, the emergence of industrial human-machine interfaces (HMIs) provides a convenient and feasible human-machine dialogue method for achieving these functions when building PLC control systems, offering a better option for the transformation of grinding machine control systems. The characteristics and functions of an industrial HMI, also known as a touchscreen monitor, are a type of operation control display device. Its hardware consists of a power supply, a touch resistive network, a display, memory, and an IYO expansion interface. An HMI is based on a specially designed computer system (a 32-bit RISC CPU chip), with a transparent resistive network touchscreen covering an STN, TFR, or EL (electroluminescent) display. When the screen is touched, the resistance and voltage on the resistor network change, and the software calculates the touch position. Main functions include: data input and display, real-time display of system or equipment operating status, setting touch controls on the HMI to use it as an operation panel for control, alarm handling, and printing. In addition, the new generation HMI also has simple programming, data processing, data logging, and intelligent control functions such as recipe processing. Application in PLC industrial control systems : 1. System Overview: The automatic cycle process of the grinding machine includes feeding, magnetization, rapid jump, rapid approach, black surface grinding, roughing, finishing, and finishing grinding. The original factory-configured control system was a UCN 281 small industrial computer, which had poor stability and a high failure rate, frequently causing equipment downtime. During the modification process, the system hardware was changed to consist of a PLC and testing instruments, and the field equipment control device consisted of stepper motors, harmonic reducers, ball screws, etc. Under normal circumstances, the operation of various grinding process control systems is coordinated according to the requirements of the production process, grinding parameters are set, and the entire grinding cycle is fully automated. The core control part of the entire system is implemented by OMRON, while the monitoring and interactive operation interface tasks are undertaken by the HMI. This mainly includes: parameter setting, dynamic screen display, grinding process parameter display, and fault alarm and diagnosis. The HMI selected is Stepper's e-VIEW-506L. 2. Communication between HMI and PLC. When the HMI is used in a PLC control system, communication between the HMI and PLC is via serial port using D-LINK (direct connection). In this mode, the HMI directly reads data from the PLC or writes data to the corresponding address of the PLC as required. Because of the built-in communication protocol, there is no need to write a communication program; simply specify the type (i.e., the communication protocol) and communication can be achieved at runtime. This greatly reduces the burden on the PLC user program. During system design, the addresses of the control components and their corresponding PLC input/output (I/O), registers (R), and intermediate registers (M) are directly specified. During operation, the HMI can automatically exchange data with the PLC. It can directly read or rewrite the contents of the corresponding PLC addresses and change the displayed content on the interface accordingly. Simultaneously, data can be input to the corresponding PLC addresses via touch operation on the HMI. 3. HMI Monitoring Main Interface The entire HMI monitoring system adopts a tree structure, consisting of a monitoring and adjustment interface (as shown in Figure 1) and corresponding functional sub-interfaces. Control function keys are provided on the main monitoring interface; touching each function key allows entry into the corresponding sub-interface to execute the required function. Within each sub-interface, the "Previous Page" and "Next Page" function keys can be used to switch between interfaces within the same function group. The "Back" function key can be used to return to the main monitoring interface from any sub-interface. The system automatically collects relevant data and displays the equipment's operating status and some process parameters on the main interface for easy observation by operators. The main monitoring interface also displays a dynamic interface of the production process (see Figure 2). This dynamic interface simulates the operation of the main control equipment in various forms, such as the equipment's location, grinding status, and grinding data, intuitively and vividly reflecting the on-site process and facilitating operators' understanding of production conditions and equipment status. The HMI programming software EasyBuilder provides a rich set of control components, such as button components, interface switching components, indicator light components, data and text display components, and animation components. To achieve these functions, simply select the appropriate control component and define its attributes. EasyBuilder adopts a general monitoring software mode, where all control component attributes are configured to achieve the corresponding control functions. Using the included library and drawing tools in EasyBuilder to construct the simulation interface of the production site is simple and easy. Furthermore, by fully utilizing the advantages of HMI, switches, buttons, and indicator lights originally located on the control cabinet can be replaced as much as possible with control components within the HMI. This reduces hardware requirements, simplifies wiring, and lowers the failure rate. [align=center] [/align]Figure 3. The main control system has many process parameters that need to be set and changed. Based on the control functions, the frequently changed grinding parameters are grouped into several interfaces (see Figure 3), making the overall system structure more rational. At the same time, the touch operation feature makes parameter setting extremely simple and intuitive. When setting parameters, the parameter setting interface can be accessed via the touch function keys. The built-in numeric keypad is designed as a pop-up key. When the operator wants to set a parameter, they touch the numeric keypad to bring it up for operation. Each data point in the HMI is defined in the component properties and assigned a corresponding PLC address. After entering the numbers sequentially, pressing the scl key makes the keypad disappear. The entered data is then stored in the address specified by the PLC. Each parameter value can also be designed with upper and lower limits. When the input value exceeds the limit, the system refuses to accept it, sends an alarm to the operator, and returns the previous data. Furthermore, important system device parameter groups cannot be modified. However, password protection can be implemented for parameter modifications in the settings interface using the EasyBuilder software's tool library, thus increasing system security. Editor: He Shiping