| Automatic Meter Reading--AMR for short--refers to reading and dealing with the whole course of the data automatically through the dedicated device by means of computer network, communication, electronic technology. Generally an intact system of AMR is made up of a lot of main stations, Reading Concentrate Units (RCU), Meter Reading terminal stations and meters. At present AMR is realized in its RCU. Its hardware platform is generally based on 8 bits or 16 bits MicroController, and its software mostly adopts single circulation control method. This system has following shortcomings: Operation ability is relatively bad; The hardware platform tends to be much dependent; In case of lacking effective multitask coordination mechanism, it is far from easy for application software to realize the task and the stability is hard to be guarantee; Distributed multitask is not good at processing, and its networked and intelligent support can not meet the needs of long-term development. The perfect combination of PC/104 module and embedded Linux can well solve above-mentioned problems. The chip and components PC/104 has adopted is suitable for various kinds of abominable working environment. Linux's source codes are free and open, and it has extensive technical support worldwide. And what's more, it can support multi-hardware platform. Its key code is small but very efficient; In addition, the system has high liability, stability and flexibility, and it is easy to upgrade. It is a multi-user and multi-task network operation system. At present AMR mainly adopts wired communication technology and power line carrier technology. As a traditional method wired communication technology prevails for its stability. However, it's a huge work to pave the lines which are subjected to be damaged. Power line carrier technology can solve this problem effectively. It utilizes the existing power line as the communication line, avoiding paving line project, so its advantage is obvious. For this reason, with reference to both at home and abroad existing results we have proposed a solution of three layers based on embedded Linux technology. Administrative center is standard PC. Intermediate level adopt standard industry embedded PC/104 series module. And the ground floor adopts the ripe data collector. When the system works, collector accumulates and stores pulse signals gathered, and translate the signals into the amount of power, water and gas etc. This sort of translation can be set in the administrative center. At the same time, Collector carries on two-way communication with PC/104 embedded system through the low-voltage power line. Reading concentrate unit is the control pivot of AMR's communication system. Every concentrator sends information to administrative center computer through Internet and it also supports remote access. Administrative center deals with sending orders, setting parameter, displaying the situation of the operating system and communicating with PC/104 embedded system. It can provide simultaneous information of each meter in each family, such as operating parameters, working conditions and history records. The database server is responsible for storing the data. As the bridge of the AMR, the RCU has following functions: ⑴Transmitting data ⑵Storing data ⑶Monitoring regularly ⑷Setting up on the spot According to this scheme, we adopt multi-task embedded operating system Linux as software platform. We adopt multi-thread programming to realize the functions planned. Then the system is divided into the following several pieces of thread: gathering data thread, analyzing thread, patrolling thread, thread dealing with network communication and main thread. From designing the angle, it is divided into three pieces of module, including: timing task module, network communication module and series communication modules. Timing collecting thread gets the data from series mouths regularly. If communication appears to be unusual, then it produces an error record. If normal, store the data into overall variable and notify the analyzing thread to...
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