With the rapid development of computer technology, a new control system subjected to the PLC, inverter speed, HMI dialogue is widely used in many fields. This article mainly introduces the system whose control center was PLC. The HMI was used as a friendly man-machine tool in this system, through the control of inverter, thus achieving the ideal operation of industrial assembly line. Siemens S7-200 series’ PLC was mainly applied in this design, TP070 and related software was used as the HMI. This paper focuses on discussing the PLC’s application in industrial assembly line, PLC’s control of station on the line and related operating procedures, and describing the related design of HMI’s picture. By doing the graduate design, I could preliminary understand the application status of PLC inside and abroad, development prospect, and the principle, logic instructions associated with it, etc After nearly three months’ researching and practicing, the original plan and result was basically achieving in this graduate design, that was the station delay and the station processing. The result concluded in this design is significant in the field of industrial control. Meanwhile, it provides the reference for PLC control applied in industry as well.
Keywords：multi-station system、assembly line、PLC controller、frequency control
