Upper Machine/Lower Machine

Upper Machine

Refers to a person can directly issue control commands of the computer, generally PC, the screen shows a variety of signal changes (hydraulic, water level, temperature, etc.). The lower machine is the computer which directly controls the equipment to obtain the condition of the equipment, generally is the plc/single chip microcomputer and so on. The commands issued by the host computer are first given to the lower machine, and the subordinate machine is then interpreted as the corresponding sequential signal directly to control the corresponding equipment. The lower machine reads the device status data (usually analog), and converts the digital signal back to the host computer. 　　In short, the actual situation is very diverse, but original aim: the upper and lower machine all need programming, there is a special development system. In the concept of the controller and the provider is the host computer is the controller and the service is the lower machine can also be understood as the host and slave relationship but the upper computer and the lower machine is can be converted two machines how to communicate, generally depends on the lower machine. TCP/IP is generally supported. But the lower machine generally has a more reliable unique communication protocol, buy the next time, will bring a lot of manual CD, tell you how to use the unique protocol communication, which will give a lot of examples, generally for programmers to look at the same thing, using some new API. 　　Multi-language Support function module, generally supporting several high-level languages for the host computer programming. Usually the host computer and the lower machine communication can use different communication protocols, can have RS232 serial communication, or the use of RS485 serial communication, when using the computer and PLC communication can not only use the traditional D form of serial communication, can also be more suitable for industrial control of the two-wire PROFIBUS-DP communication, the use of packaged program development tools can be realized plc and host computer communication. 　　Of course, you can write the interface protocol of the driver class to control the communication between the host computer and the subordinate computer. Usually industrial computer, workstation, touch screen as the host computer, communication Control PLC, microcontroller and other lower machine, so as to control the related equipment components and drive device.