Environmental Monitoring Network Based On ARM

Daya Bay Reactor Neutrino Experiment is a large-scale international cooperation projectunder the auspices of the Institute of High Energy Physics,Chinese Academy of Sciences.Thephysical goal of the Daya Bay neutrino experiment is a measurement of the sin22θ13, and themeasurement accuracy reaches above0.01. As a result, we need to design very lowbackground detectors and high-precision electronics system, and the experimentalenvironment on the performance of detectors and electronics is an important factor toconsider.In order to ensure the sensitivity of the Daya Bay experiment, the research content ofthis subject is long-term monitoring and controlling of many parameters that affect thedetector performance.There are three observation points for the entire experimental device, and two each apartfrom two thousands metres. All devices locate in the cave below, and they are required to beable to collect the data of the distribution device, and need to achieve communication betweenthe two data flows, local display and control, also need to be able to network interconnection.At the same time, the monitoring equipments distribute throughout the entire experimentaldevice, so it requires device miniaturization and high reliability. Therefore, this paper proposea monitoring device with ARM-based embedded operating system (Linux), openness,miniaturization, strong features, network connectivity, building a friendly human-machineinterface (embedded operating system) and so on functions.This environmental monitoring network consists of three parts: field acquisitionterminal, communication control unit and terminal server. Acquisition terminal chooses singlechip microcomputer as the front end to collect equipment; communication control unitconstructs the acquisition device based on ARM, with embedded Linux operating system;terminal server processes command and service two kinds of data based on DIM platform.The whole environment monitoring network data flow can be devided into two parts: theupdate of service data and the response of command data. Data update part is as follows:firstly, microcontroller drives sensors, and collects humidity, temperature, and pressure datafrom sensors, and then transfers the data to the communication control unit via custom485communication protocols; secondly, linux operating system embedded in the communicationcontrol unit extracts valid data package from the buffer; finally, the data packet are uploadingto the terminal server by TCP/IP Ethernet. The command response part is to respondcommand from the remote terminal server on time, and change the configuration informationof the communication control unit via a web server. According to the proof of testing and trial operation, the monitoring network is stable,reliable, and its precision and speed meet the project requirements.