Industrial automation control is mainly divided into three parts: industrial automation systems, hardware, and software. Currently, commonly used industrial automation control equipment and systems include servo systems, stepper systems, frequency converters, sensors, instruments, human-machine interfaces, data acquisition and monitoring control systems, distributed control systems, programmable logic controllers (PLCs), and fieldbus control systems (FCS).
After years of development, the structure and core components of modern industrial automation control have begun to take shape:
1. Programmable Logic Controller (PLC). A Programmable Logic Controller (PLC) is a digital electronic system specifically designed for industrial applications. It uses a programmable memory to store instructions for performing logical operations, sequential control, timing, counting, and arithmetic operations, and controls various types of mechanical equipment or production processes through digital or analog inputs and outputs.
2. Redundancy technology for data acquisition and monitoring control system (high system reliability).
SCADA system. A Supervisory Control and Data Acquisition (SCADA) system is a software application whose main functions are to collect system status information, process data, and communicate over long distances to control equipment and conditions.
3. Remote Terminal Unit (RTU). A remote terminal unit (RTU) is a specialized computer measurement and control unit with a modular structure designed for long communication distances and harsh industrial environments. RTU products are widely used in SCADA systems.
4. Communication Technology. Industrial control systems use three communication methods based on their hierarchical structure: standard communication bus (external bus), fieldbus, and local area network (LAN) communication. These methods connect the host system to various devices, transmitting field signals to the control level, and then transmitting control-level information to the monitoring and management levels.
5. Protocols. Communication between the field network and the control network of an industrial control system, communication between various industrial control devices in the field network, and communication between various components of the control network often employ communication protocols specific to the industrial control system. Currently, protocols involved in industrial control systems include fieldbus (CAN, DeviceNet, Profibus-DP, Profibus-PA, etc.), industrial Ethernet (EtherNet/IP, EtherCAT, HSE, Profinet, EPA, Modbus, etc.), and industrial wireless networks (IEEE 802.11, ZigBee, Rfieldbus, etc.).
