Development Of Smart Pressure Recorder Based On Modbus Protocol

Because the current domestic production of differential pressure loggers are mostly stand-alone instrument that do not have the fieldbus networking features, it is necessary to inspect each instrument recorded by differential pressure recorder to gather statistics differential data. This approach is not only inefficient, but also likely to cause data errors or miss records due to the presence of human factors. Commissioned by Hefei Dewey Instrument Technology Co., Ltd., an intelligent differential pressure recording instrument based on modbus communication protocol is developed to solve the problem of traditional instrument.The differential pressure data logger displays the current data on a dot matrix LCD screen, supports maximum 100 000 groups of the differential data records, and can classify the data automatically according to the time node. Data playback was completed on computer, as the current and historical data can be queried by the RS-232/RS-485 bus based on the modbus serial communication protocol. In addition, the differential pressure recorder also has a variety of functions that can be set, such as differential value limit alarm and RTC clock display. In this paper, the main work content is divided into hardware circuit design and software design, including LPC1768 ARM microcontroller peripheral circuit design and signal amplifying circuit design as well as FatFs file system and FreeModbus protocol stack migration, etc.At present the Smart Pressure logger has been put into the market, earning a good response, and a good economic benefit has been created for the enterprise.