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1. Project Background
With the continuous improvement of people’s living standards, the people have put forward higher requirements for the living environment; inspired by government policies, home automation has developed rapidly. As a link in the intelligent industry chain, the intelligent meter reading system has also developed vigorously at the same time. The traditional manual meter reading method is time-consuming and labor-intensive, the accuracy and timeliness cannot be guaranteed, and there will be some unpleasant embarrassing situations for meter readers and users, which are no longer suitable for the development needs of society. This also puts forward higher requirements for meter reading. For this reason, we propose a new meter reading solution – wireless meter reading. At present, there are basically two data transmission methods for meter reading in residential areas, wired data transmission and wireless data transmission. If the data is transmitted by wire, the technology is simple, mature, and easy to implement; however, the construction and wiring workload is large, and the network cable is vulnerable to man-made damage. After the line is damaged, it is difficult to find the fault point. If a wireless system is used, the construction is very simple, the system is easy to maintain, and faults are easy to find. Therefore, wireless meter reading will become the mainstream of the development of meter reading methods. The program is mainly aimed at the copying of residential electricity meters.
Second, the analysis and construction of the system
The construction of wireless meter reading system is mainly the construction of wireless network. The whole system is divided into three parts: data acquisition part, wireless networking part and data management part.
1. Data collection part:
Data is divided into command data and collected readings. In the whole system, data transmission is in the form of data packets, and the transmission direction of command packets is opposite to that of reading data packets.
Data acquisition refers to reading the data of the electric meter and transmitting the data to the data management terminal through a certain transmission method. The data collector is connected to each meter on the floor through the RS485 bus. Each collector is equipped with a wireless data transmission module, and the collected data is sent out through the wireless data transmission module. Its schematic diagram is shown in Figure 1:
2. Wireless networking part
The wireless network is divided into two parts of the wireless network: the building internal network and the base station network. The whole network adopts the networking form of tree structure.
The wireless network adopts the networking mode of address association and tree structure. Each data packet has an address, and its address determines the direction of data transmission, whether to upload or download.
2. 1st floor internal network:
The intra-building network refers to the wireless networking between the collectors on each floor in a building.
The collector on each floor directly sends the data to the base station of the building through the wireless transmission device, and finally the base station sends it out. If the collector and the base station cannot communicate directly, relay forwarding is used. The network follows the principle that the shorter the link, the better. Its data transmission is shown in Figure 1.
2.2 Base station network:
The base station network refers to the wireless network between buildings. The top of each building is equipped with a base station, which is used to transmit the data collected by this building and forward the data of other buildings. The shorter the network compliance link, the better, and the one that can be reached directly does not use a relay. Its network diagram is shown in Figure 2:
2.3 Handheld
The handset is the bridge connecting the community and the management department. The handset downloads and saves the data from the main station of the community in the form of wireless, and then transfers the data to the PC of the management part by wire. The management part can also use the handset to send data at the terminal. Instructions such as meter reading and valve control are transmitted to the base station network through the central station until it reaches each meter, so that the meter can perform corresponding operations.
Another use of the handset is to address all wireless devices in the system.The handset is shown in Figure 3
3. Data management part
The meter reader only needs to go to the main station of each community to download the data to the handheld, and then use the handheld to download the data to the PC through the cable, and the PC can effectively manage the collected data through the database. The management database uses the three-table data collection and management system designed by our company.
3. Wireless module
The wireless module uses the wireless remote data transmission module ZF-02 independently developed by our company. (The module has an automatic avoidance function. When it detects that there is a module sending data, it will not send it by itself. It will not start until no other modules send data. The sending function sends the data to be sent, avoiding the interference phenomenon.) The wireless module is connected to the collector and the base station, and is used to collect the reading of the meter and store it for transmission. The time automatically wakes up to detect whether there is a wake-up signal from the outside world (mainly used by the collector to copy data). If a wake-up signal is detected, it will wake up and wait for the next instruction to perform related operations. If there is no wake-up signal, it goes to sleep again. In this way, the power consumption of the wireless module is very low, and if it is powered by a battery, it can reach 1 to 3 years.
Fourth, the communication protocol
In the system, the communication protocol and data format between the wireless module and the meter are communicated and defined in accordance with the “People’s Republic of China Urban Construction Industry Standard (CJ/188-2004) – Technical Conditions for Data Transmission of Household Meters” .
5. Features of wireless meter reading system
1. The wireless module is multi-channel and multi-baud rate (selectable by the user); the hardware adopts high-precision integrated packaging technology, with small frequency offset with changes in ambient temperature and humidity, accurate measurement, and reliable communication; micro-power, long communication distance, Price is low.
2. The wireless meter reading device is easy to carry, simple and intuitive to operate, and rich in functions.
3. The system is highly integrated and the total cost is low.
4. Data can be copied at any time.
5. Do not enter the home to read the meter to avoid disturbing the people.
6. With valve control function.
7. Simple system and high meter reading efficiency
Shanghai Zhaofu Communication Technology Co., Ltd.
Dong Jun: 13482884948
021-51822510-14
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