Design Of Intelligent Meter Based On MODBUS Protocol

With the development of industry production scale, the demand of centralized monitoring is becoming urgent in producing process. So the emergence of fieldbus caters to the stronger long-distance communication function which the field testing control instrument has. Modbus bus, for its lower development costs and ease of use, has been widely used in industry fields. By Modbus bus, the control devices which are produced by different manufacturers can be linked into an industry network conveniently to centralize monitoring. According to the demands of intelligent instrument development, a solution scheme is put forward in this thesis, which is based on C8051F020 and Modbus protocol. Besides, this paper also refers to the detailed design and development of the software and hardware which are related to the above mentioned solution scheme.C8051F020 SCM is selected as a controller on hardware in the thesis. The used quantitiy of instruements decreases, because C8051F020 not only has 12-bit 8-channel ADC0, but also collects 8-channel simulation. At the same time, the LCD display module of the controller which is used by T6963C in the project, realizes dynamicly display collected datas and running curve. The active nonvolatile memory FM31256 with clock is adopted as the extended memory. It not only makes sure real time data retention during power down and provides system clock, but also overcomes such shortcomings as complex circuits and high cost brought by the traditional scheme utilizing separable parts. In addition, this instrument has the RS485 serial communication interface supporting Modbus protocol. It can send its own status and field parameters to supervising host computer. The hardware of this instument has adopted multiple anti-interference measures to improve the stability of the system. This project has developed some related software modules, such as display module, extended memory module and communication module, etc.The real running indicates that this intelligent instrument improves the disadvantages of the traditional industry instruments in data display and telecommunications fields. And this intelligent instrument is better than the traditional one in stability, real time and precision. Besides, contrasting to the traditional instrument control system, the new one which is based on this intelligent instrument has the following advantages: fault-tolerance, data exchange, system management and anti-interference, etc.