Design Of Remote Data Acquisition System Based On Ethernet

Earthquake, which is one of the most destructive geologic hazards, causes heavy casualties and huge financial losses every year. So how to adopt effective scientific methods for earthquake monitoring and warning has been a mission of modern science researchers. So far, various monitoring methods have been proposed, among which the earth tilt monitoring method is a way to monitor relative movement of the earth's crust and the dynamic changes of the solid tide through the earth tilt. Due to the relative earth tilted variation is so small that it is susceptible to external noise, the tilt observatory is generally placed in the stable and isolated region at seismic stations.In this paper, the related data acquisition system is under-study and a remote data acquisition system based on ARM+MCU+Ethernet is proposed which takes advantages of Ethernet's low prices and high speed, MCU's low-cost and easy development and ARM's strong processing ability, fast arithmetic and rich on-chip resources and peripheral interfaces. It consists of the field data acquisition devices and remote control terminal.System hardware circuit is selected and designed which includes ARM main control circuit, MCU co-controller circuit, front-end conditioning circuit, high-precision analog-digital conversion circuit, isolated digital IO circuit, serial communication circuit, high speed Ethernet communication circuit and system power circuit, and so on.The remote control terminal is designed. Compared with TCP, UDP is chosen as the basic protocol at transport layer and an improved communication method is proposed.Embedded Linux operating system and Keil are used as the system development environment and the program is divided into three sections by functionality: network communication thread based on improved UDP, data acquisition and control thread based on serial communication and co-control program, which are designed in detail subsequently.At last, test results show that data acquisition device can realize sample, A/D conversion and data storage with 14-bit or more resolution and remote control terminal can be used to control seismic monitoring sensors and access and download acquisition data from the related device, which are compliance with system design requirements. At present, this remote data acquisition system has been applied in the seismic monitoring and proved to be stable and reliable after a long period of observation and comparison with the existing testing equipments.