本研究乃根據環保署空氣品質監測站資料收集系統未來之需求為開發方向，設計開發一套儀器資料收集系統，以大量、即時傳遞監測資料。設計時應用現代化之網路及通訊技術，並納入分散式管理、嵌入式系統設計等先進概念。共計開發資料收集原型機六部及軟體應用程式三套(系統控制程式、常駐資料封包轉換程式、使用者操作介面)。系統主要功能包括： (1)具網路資料傳輸功能 (2)遠端控制/自動設定參數之功能 (3)具初步自我除錯/自我救援之功能 (4)採分散式資料管理，具多重資料備份之功能 (5)具有數位/類比儀器資料接收及控制功能 (6)內建校正曲線及監測值轉換之功能 (7)具資料儲存功能 (8)以網頁式(Web-based)應用系統為操作介面 由實驗室功能測試結果顯示：原型機資料收發、自動除錯/自我救援功能、資料自動備援及修復機制等功能皆能正確執行，且測試期間原型機穩定操作時間佔總測試時間之95%以上。在實驗室測試中，使用學術網路進行資料傳送時的封包遺失率約為0.02%、網路控制反應時間約為4~5秒。實場測試時由於網路條件的不同，其平均封包遺失率約為0.01%~0.04%、遠端設定成功率在95%以上、網路搖控反應時間約為4~5秒。在未啟用看門狗功能前，由於缺少外部救援機制，當機時需由人工重新啟動，造成系統資料收集工作停擺，此情形在啟用看門狗功能後獲得成功改善。加入看門狗功能的原型機在實場測試後期已能自動連續運作達一個月之久。 The purpose of this research is to design and develop an internet-based SCADA (Supervisory Control and Data Acquisition) system to meet the demand on data collection and transmission of the environmental monitoring stations around this island in the future. The system is composed of two parts：an on-site data collector which is called Site-Server, and a PC-based web server unit at the remote data center. Site-Server has a signal processing unit based on BX-24 microprocessor, an internet protocol processing unit based on siteplayer chip, and other peripheral chips. The system can take both analog and digital signals from different monitoring instruments and transmit calculated data to 8 different subscribed remote databases. Before data are transmitted, the Site-Server stores data in its nonvolatile memories as a backup in case of internet failure. The major functions of this system are listed below： (1)Internet data transmitting and receiving (2)Automatic parameter configuration (3)Preliminary system debugging and rescuing (4)Multi-users data subscription (5)Digital signal conversion (6)Voltage-to-data translation (7)Inner data-logger (8)Web-based human-machine interface Laboratory and on-site tests were put into practice later to evaluate the performances of the system. The laboratory test showed that the steady operation time of Site-Server had reached 95% of the entire period. Other tests such as power failure test, internet service interruption test, and database replication test were also carried out successfully. In field situation, the probability of losing data during transmission was about 0.01%~0.04%, and the access time through internet was about 4~5 seconds. For unknown reasons, Site-Server halted more often in the beginning of the field study. This problem was solved by adding an external watchdog timer. Since then, the system worked steadily.
