Design And Research Of Liquid Level Communication Monitoring System Based On DELPHI

With the rapid development of information technology and computer technology and internet communications, the fieldbus device, intelligent device or lower machine, such as single chip control system, PLC control system, were integrated closely by the computer interface, which has changed the traditional industrial control methods, has greatly promoted the process of industrial automation. At the same time, the use of computer equipment to achieve the production process for remote centralized monitoring and management of industrial safety and economy also plays a very important role.In this paper, the object of control is cascade water tank, it is described the design and implement process of level communication monitoring system in detail. The system mainly consists of two parts design:the upper computer monitor partial and the lower computer control section.The lower computer control system is mainly selected S7-200 series PLC as the master controller to control the field devices, the operational status of each pump, the liquid level, flow, pressure and other signals which is detected by the sensors is put into the storage unit of PLC for processing by the A/D conversion. Then the collected value was compared with the set value, When the liquid level exceeds the set limit, water flow is regulated by the inverter, so that the liquid level achieves a dynamic balance.The upper computer use Delphi as the control interface, the host computer and lower computer communications is completed by MSComm control, the collected parameters are displayed in the monitoring interface. When the measurements collected deviate from the setting value, the host computer automatically gives the alarm on the computer screen. In addition, when the monitoring system is running online, operator can put into the control information on the host computer, and modify a control parameter, then send these information to the field instrumentation and control units, thereby change the operating mode online and the running state. the host computer has completed the setting of login, real-time trends displaying and historical data saving by the database technology so that data is easy to managed, archiving and query.