In industrial automation control, we can divide the control field into four layers: field acquisition layer, field control layer, local operation layer, and central management layer. These layers are interconnected by networks. Below is a bottom-up analysis of each layer: Field Acquisition Layer: Primarily composed of field devices such as sensors and actuators, equipped with bus communication modules. Fieldbus: Field devices connect to the controller via fieldbuses such as CAN, LonWorks, and PROFIBUS. Field Control Layer: Through logic controllers such as PLCs and PACs, equipment can be monitored via the fieldbus. Traditional distributed control can also be achieved through I/O signals. Local Network: This can be a fieldbus, such as CAN or PROFIBUS, or other communication networks supported by various equipment manufacturers, such as MPI networks or other local area networks used in industrial settings. It serves as the channel for transmitting information from the controller to the operation control platform. Local Operation Layer: The industrial computer monitoring the field uses various configuration software to acquire, display, and store data. It can also control and configure the controllers below. Because modern controllers support multiple communication methods, this layer can extensively utilize HMI products that run configuration projects for monitoring, control, and data uploading. Simultaneously, portable debugging equipment can be used for real-time maintenance of controllers and HMI products. For example, Siemens' TP270HMI product can be used for system monitoring and control, while Siemens portable encoder PG products or laptops (with serial and Ethernet network communication ports) equipped with Siemens HMI software and STEP7 series PLC programming software can be used for TP270HMI configuration project maintenance and modification. This also allows modification of PLC controller logic commands and monitoring of controller operation. Management Network: This can be Ethernet, or even the Internet, such as a factory area network, 802.11G wireless network, modem network, GPRS network, etc. It is primarily responsible for uploading large amounts of field data and remote management. Central Control Layer: This hardware platform, composed of industrial computers or high-end HMIs, runs integrated industrial configuration software for management and control. It performs statistical analysis, calculation, and storage of large amounts of data from the industrial field, generates reports, and is responsible for remote monitoring, scheduling, and management. Analysis reveals that the human-machine interface (HMI) occupies a central position in the current integrated control system. It connects to the fieldbus, enabling field operation and management of the upper-level bus logic control system. Simultaneously, it is responsible for aggregating field data and uploading data relevant to the central management layer. Therefore, abundant hardware communication interfaces and diverse software communication processing functions are key characteristics of the HMI system.