In the field of industrial automation control, it can be divided into field acquisition layer, field control layer, local operation layer and central management layer. At the same time, there are network connections between the layers.

Here let's analyze each layer of the control site from bottom to top layer by layer:

Field acquisition layer: mainly composed of sensors, actuators and other field devices, with bus communication module.

Field bus: field devices are connected to controllers through field bus, such as CAN, LonWork, ProfiBus, etc.

Field control layer: through the logic controller such as PLC, PAC, etc., it can monitor the equipment through the field bus, at the same time, it can also realize the traditional distributed control through the I / O signal.

Local network: it can be field bus, such as CAN bus or PROFIBUS bus, and it can also be other communication networks supported by various equipment manufacturers, such as MPI Network, LAN used in other industrial sites, etc. It is the channel for the information of the controller to be transmitted to the operation control platform.

Local operation layer: the industrial computer monitored on site, which collects, displays and stores various data through various configuration software, and can also control and set the lower level controllers. Due to the current controller supports a variety of communication methods, this layer can use a large number of man-machine interface products running configuration engineering, such as monitoring operation, control, data upload, etc. At the same time, portable debugging equipment can be used for real-time maintenance of controller and human-machine interface products. For example, use Siemens TP270HMI product for system monitoring and control, Siemens portable encoder PG product or notebook with Siemens HMI Software and STEP7 series controller PLC programming software (with serial port, Ethernet and other network communication ports) for TP270HMI configuration engineering maintenance and modification, at the same time, you can modify the logic command of PLC controller, monitor running status of the controller.

Management network: it can be Ethernet or even Internet, such as plant area network, 802.11G wireless network, MODEME network, GPRS network, etc. Mainly responsible for a large number of on-site data upload and remote management.

Central control layer: a hardware platform composed of industrial computer or high-end human-computer interface, which runs the integrated industrial configuration software of management and control, makes statistics, calculation and storage of a large number of data on the industrial site, forms reports, and is responsible for remote monitoring, scheduling and management.

Through analysis, the human-computer interface is in the core position of the current integrated management and control field, connecting the field bus, completing the field operation and management of the upper layer of the bus logic control system, and at the same time, being responsible for summarizing the field data, uploading the data concerned by the central management. Therefore, the hardware communication interface is abundant, and the software has a variety of communication processing functions, which has become one of the important characteristics of human-computer interface system.