Programmable controller (PLC) is ge

Programmable controller (PLC) is general automation device using computer technology as the core, and has been widely used in industrial production due to its high reliability, variable control program, and strong adaptability for all kinds of vicious environments [1]. But the PLC controller itself does not have the human-computer interaction devices such as display, and can't realize the online adjustment of the control parameters and the display of the system motion state. So an operation display system, which reading temperature by the intelligent meter, using PLC as the core, industrial computer as the control and operation center, is designed. The real-time display of the data and the on-line modification of the instrument set data can be realized in this design. Because in practical applications, the industrial site temperature need be reflected and controlled timely, the good communication between up-computer in the control room and down-machine in the industrial site is very important. In this design, the up-computer is industrial control computer, and the down-computer consists of a Siemens S7-200 PLC and 20 artificial intelligence temperature controllers which type is YuDian AI –708. The key to implement the above functions is the serial communication between PLC and the AI-708 instrument. Therefore, S7-200PLC and AI-708 instrument communication is the focus of this design.