Design And Implementation Of Remote Thunder Monitoring System Based On COM

By the statistic of related departments, thunderstorms happen averagely 2000 times all over the world every minute. Over 10000 persons are injured by thunders in the seven seas, the losses of thunders reach 5-10 billionï¿¥in China. The remote thunder monitoring system can reduce the losses of thunders by monitoring thunder alarms remotely, which main function is similar with automatic alarm systems of fireproofing or guard against theft. The hardware of system consists of thunder probes, digital receiver and monitor PC. Digital receiver is SG-SLR, which includes single thread and multiple formats, receiving alarms by thunder probes in real time. But SG-SLR can't directly show thunder alarms for its limitation, which is difficult for system administrators to master concrete alarms. So the software component of this system is designed and implemented by Borland Delphi 6 and Microsoft Access 2000 RDBMS, which runs on monitor PC to extend functions of digital receiver.Software component is the software development technology based on software reuse and socialization. Software reuse can make encapsulated software modules be used for many times or placed into different systems for requirements, which may enhance development speeds, software qualities and agilities, reduce development and maintenance costs. The software based on component technology isn't solidified system but can satisfy integrations, agilities and expansibilities. At present the most popular software component technology includes Microsoft COM/COM+, OMG CORBA and Sun JavaBeans. Among them, COM (Component Object Model) is mostly applied in Windows and has become one of the component standards. Software developer can integrate all sorts of components with COM, which is like hardware chips.This article discusses design and implementation of the system software based on COM, including serial communication, data management, alarm show and the extension of network function because the platform of system software is Microsoft Windows.Delphi can import ActiveX controls, so MSCOMM is used to implement RS232C serial communications between monitor PC and digital receiver by OnComm event driven. Analysis on SG-SLR proves Monitor PC needs to handle test and alarm information. Digital receiver sends test information to monitor PC every 30 seconds, which tests whether communication is normal. Test information includes 21 characters: the ASCII codes of first three characters are 31H, 30H and 31H; the last character is 14H. When monitor PC received test information from digital receiver, it needs to send a character which ASCII code is 06H back. When digital receiver received thunder alarms, it sends alarm information to monitor PC in no time. Alarm information also includes 21 characters: the ASCII code of first character is 35H; from the eighth to the eleventh, these four characters show alarm user ID; from the eighteenth to the twenties, these three characters show alarm probe ID; the last character is also 14H. When monitor PC received alarm information from digital receiver, it also needs to send a character which ASCII code is 06H back.When monitor PC received thunder alarms from SG-SLR, the system software saves them into database in no time. User, alarm and system data need to be managed, ADO (ActiveX Data Object) and SQL (Structured Query Language) implement them.The system software is mostly extensions of SG-SLR, so alarm show is the most important part. Automatic list is basic show, monitor panel can divide users into different types, map locating make system administrators master the exact location of alarm user in time and the whole system run better. In addition, user and alarm data can also be browsed on LAN to satisfy more users, which is based on DCOM (Distributed COM).Now the remote thunder monitoring system runs well, it was applied in weather bureau of jilin province and spread many other areas.