Study On Monitoring System Of Centrifugal Fan Based On Delphi And Siemens' PLC

With the development of micro-electronics, computer, telecommunication and networks, industry automation is the trend of the industrial control in the 21th century. Generally, PLC plays a very important role on the field of the industrial automation control. But the ability to manage data is limited, and cannot provide good human-computer interface. Then high-efficient control system should be needed to make PLC combine with PC efficiently.In this paper, an automatic monitored control system is designed based the industrial centrifugal as the subject. The main tasks are as follows:(1) Filed Instruments and signals needed to be collected and controlled in the running of fans are listed. In this paper analyses interlocking conditions and logical relations of start, stop, normal operation and alarm of fans, then classifies the signals into digital signal and analog signal. After the proper selection of S7300CPU, input and output modules of Siemens, defining symbols and assigning address of I/O should be done. At last, it is to programme and input by using STEP7soft.(2) Human-computer interfaces are designed by DELPHI for monitoring the real-time operation, which include log-in, structure, oil way, alarm and parameter setting and put all state parameter(speed, temperature, vibration, oil charge and so on) into one picture in order to update fan operation conditions, analyse alarm and store historical records. The character of the human-computer interface is handleability, observability, humanized. (3)The application of MPI and PRODAVE soft provided by Siemens is to realize the data change of PC and PLC. PC communication port (COM) and MPI port of PLC are connected by a cable programming on the hardware. Delphi reads and writes data of PLC's storage area through calling relative library functions in the PRODAVE to complete the data exchange.