Introduction to electronic information systems-Upper and Lower computers
Recently, when I was working on an automated information system project, I had a lower computer for a while. It was a bit mysterious for me, a cainiao who had never engaged in hardware development, it is a supplement to popular science knowledge.
PC refers to a computer that allows a person to directly issue control commands. Generally, it is a PC, and various signal changes (hydraulic pressure, water level, temperature, etc.) are displayed on the screen ). The lower computer is a computer that directly controls the device to obtain the device status, generally PLC/single chip microcomputer. The Command issued by the upper computer is first sent to the lower computer, and then the lower computer directly controls the corresponding device based on the command as the corresponding time series signal. The lower Computer Reads device status data (generally analog) from time to time and converts the data into digital signals for feedback to the upper computer. In short, the real situation is different and different. Both the upper and lower computers need programming and all have specialized development systems.
In addition, the upper and lower computers communicate with each other through different "physical" layers. Generally, the lower computer is responsible for frontend "Measurement and Control" processing, and the upper computer is responsible for "management" processing. The lower computer is the execution unit that receives commands from the primary device, that is, the slave device. However, the lower computer can also directly and intelligently process measurement and control execution; the host computer does not participate in specific control and only manages (data storage, display, and printing ...... man-Machine Interface ). A common DCS system is a centralized-distributed (distributed) system.
In terms of concept, the controller and the provider are the upper computer. The lower computer can also be understood as the relationship between the host and the slave machine. However, the upper computer and the lower computer can be converted.
The communication between the two machines generally depends on the lower computer. TCP/IP is generally supported. However, the lower computer generally has a more reliable and unique communication protocol. When purchasing the lower computer, it will bring a lot of manual CDs to tell you how to use the special protocol for communication. There will be a lot of examples. This is generally the case for programmers. They just need to use some new APIs. Multi-language support function module. Generally, it supports programming in several advanced languages at the same time.
