In modern industrial automation and intelligent control systems, the concept of upper computer and lower computer is the core component. Together, they form a hierarchical control architecture that enables complex control tasks to be executed efficiently and in an orderly manner. This article will introduce in detail the definition, functions, hardware requirements, communication methods, and application scenarios of the upper computer and the lower computer, as well as the main differences between them.
Schematic diagram of the relationship between the upper computer and the lower computer
What is a host computer?
Host computer usually refers to a computer system with powerful computing power and data processing power. It is responsible for the monitoring, instruction issuance, data acquisition, processing and analysis and user interaction of the entire control system. As the "brain" of the system, the host computer can process complex algorithms, carry out long-term data storage, and provide a graphical interface for users to operate.
Schematic block diagram of host computer control
The hardware of a host computer usually includes a personal computer, an industrial PC, or a server. These devices are equipped with high-performance CPUs, large memory and storage space, and a variety of I/O interfaces. They run a complete operating system, such as Windows, Linux, or other real-time operating systems, to support complex applications and network services.
The host computer exchanges data with the lower computer through various communication interfaces, including serial ports (such as RS232, RS485), USB, Ethernet, WLAN, etc. The host computer supports a variety of industrial communication protocols, such as Modbus, Profibus, CANopen, EtherCAT, TCP/IP, etc., to achieve interconnection with the lower computer.
Host computers are widely used in industrial automation, process control, monitoring systems, data acquisition and analysis, intelligent building management and other fields. They are usually located at the highest level of the control system and are responsible for coordinating and managing the operation of the entire system.
What is a lower computer?
A slave device is a device or controller that is directly connected to hardware such as sensors and actuators in the control system. It is responsible for executing the specific control instructions issued by the host computer, such as the output of the switch signal, the adjustment of the analog quantity, the acquisition of data, etc. The lower computer usually performs simple logical judgment and real-time control tasks.
The hardware of the lower computer usually includes a microcontroller, a PLC, an embedded control board, etc. These devices have some computing power, but they are nowhere near as powerful as the upper computer. They may run a simplified operating system or no operating system (bare metal) and have I/O interfaces for direct connection to sensors and actuators.
The lower computer receives the control instruction of the upper computer through its communication interface, and feeds back the execution result or the collected data to the upper computer. The communication protocols they support are usually simple and must match those of the host computer to ensure the correct transfer of information.
The lower computer is widely used in machine control, production line automation, environmental monitoring, smart home control and other fields. They are usually located at the lowest level of the control system and are directly connected to the physical devices in the field.
The difference between an upper computer and a lower computer
Although the upper computer and the lower computer work together in the automatic control system, there are obvious differences between them:
(1) Processing power: The upper computer has stronger data processing capabilities, while the lower computer focuses on real-time control.
(2) System level: the upper computer is located at the upper level of the control system, responsible for decision-making and monitoring, and the lower computer is located at the bottom level, responsible for performing specific tasks.
(3) Hardware configuration: The upper computer has a higher hardware configuration and runs a complete operating system, while the lower computer has a lower hardware configuration and may not run the operating system.
(4) Communication protocols: The upper computer supports more diverse communication protocols, while the lower computer usually supports limited and specific protocols.
(5) User interaction: the upper computer provides a user interaction interface, and the lower computer does not directly interact with the user.
Upper computer and lower computer play different roles in the automation control system, and their design and function complement each other. As the management center of the system, the host computer provides powerful data processing and user interaction capabilities. The lower computer is used as the on-site execution unit to ensure the real-time and accuracy of the control task. Understanding how they differ and work together is critical to designing and implementing an effective control system.
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