Data transmission demand analysis
21 (household) special temperature collection points were selected for 24-hour temperature collection in the entire development area under its jurisdiction. Establish an outdoor temperature collection point in the Property Management Center of the Development Zone, and install the water temperature collection equipment for the boiler outlet pipe and return pipe in two boiler rooms under the jurisdiction of the Development Zone Property Management Center, and provide real-time temperature display on the site.
The data transmission method can be: wired or wireless. For the characteristics of the geographical distribution of the development zone, if the cable method is selected to make the cost high and the workload of the construction is large, the wireless method is adopted; the wireless method can be adopted. ZIGBEE, bridge connection, GPRS transmission, etc. According to the site survey, due to the geographical distribution of Yanqing Development Zone, each cell is far away from each other, and the distance between each temperature point is also far away. The top of residential buildings is not allowed to be installed. Bridge antenna, the final decision to complete the use of GPRS transmission.
System composition and networking scheme
The project is divided into three parts: the remote point (household home, outdoor, boiler room), wireless transmission link, and central control room.
The remote point is divided into three parts: temperature acquisition, data transmission, and boiler room temperature display. High-accuracy temperature acquisition sensor is used, with a temperature resolution of 0.1°C and supplemented with temperature compensation. The boiler room temperature acquisition equipment also has analog-to-digital conversion and display functions, which can provide real-time temperature information to field workers. The wireless transmitter can upload the collected data according to the upload time interval set by the user, so that the device can work normally when unattended.
Wireless transmission links use GPRS data transmission. The remote point data transmitter sends data to the GPRS network, and then enters the Internet network through the wireless carrier network to transmit to the application server, and the application server forwards the data to the client's host computer control software. Realize wireless data communication between the central control room client software and the remote point GPRS data transmitter.
The central control room uses a computer with a Microsoft Windows XP operating system and Microsoft Office 2003 office application software as a client. The client software is used to collect, monitor, and set functions on the site. The client software must implement data storage, data management, graphs, and data export functions.
1, GPRS data transmitter structure
* The GPRS data transmitter does not start the GPRS wireless transmission module during non-data transmission. It only starts up when it needs to send data. This function is controlled by the CPU control unit. When the CPU control unit transfers data and collects data, it enters the power saving mode to save battery power. When the CPU control unit is waken up according to the time set by the user, the data is serially collected, stored, or GPRS wirelessly logged in, and the data is uploaded after login. The GPRS data transmitter has two indicators: power indicator and online indicator.
* The data transmitter is a wireless data acquisition and transmission terminal based on GPRS. It uses the "MCU + GPRS Modem" program to receive temperature data through the RS232 interface. Then the temperature information, device name and other data are coded into IP packets and connected through the GPRS module. Into the GPRS network.
2, GPRS data receiving server structure
* GPRS data receiving server takes the existing PLC board as the core control, and the watchdog module monitors the PLC working status and resets if there is any abnormality. At the same time provide the required indicator display in the device shell. The indicator light is controlled by the PLC and the watchdog, respectively: power indicator, network indicator, and working indicator. The working status indicator flashes once every second for 1 second, indicating that the watchdog is working properly. The data received by the GPRS module can also be transmitted to the terminal equipment through the RS232 port. The watchdog is mainly used to prevent the terminal system from crashing, and the power management realizes the timing wake-up and the sleep mode.
3, client software
* The console software and the database setup carrier are computers. It has the setting of time for online and offline transmission equipment; setting of data acquisition function; collection of temperature data for storage; manual collection of current data; data query; operation log and other functions; graph generation; data export.
* The system block diagram is as follows:
System specifications
1, GPRS temperature acquisition transmitter
* Microcontroller: Use ATMAG128L, 7.3728Mhz.
* Communication module: ZTE ZTE ME3000.
*Power supply: AC220V/DC6V.
* Data Interface: An RS232 interface with a baud rate of 9600 bps.
*LED indication: Power indicator, online indicator.
* Antenna interface 50Ω/SM5 female.
* SIM card holder.
* Operating temperature: -30°C ~ +70°C.
*Working relative humidity: 95%@+40°C.
2, client software
* Database: Access local version
* Display ratio: more than 800×600
* Operating System: Window 2000/XP
*Recommended configuration: RAM 512MB, CPU P4, 1 Ethernet port, 1 serial port
* Minimum configuration: RAM 256MB, CPU P3, 1 Ethernet port, 1 serial port
* Network requirements: The GPRS wireless data acquisition console software requires 24-hour real-time online to ensure that the remote point data transmitter transmits data to the GPRS wireless data acquisition console software for storage.