With the development of technology, the meter reading method has also changed from on-site manual meter reading to remote automatic meter reading. At present, there are various techniques for meter reading, such as RS 485 bus, infrared and power line carrier, etc. These comparisons are relatively comparative. Mature, but the application has its own limitations, such as RS 485 bus meter reading requires wiring to increase investment, and the transmission distance can not exceed 1 200 m, infrared meter reading requires manual on-site meter reading, power carrier meter reading due to electromagnetic interference, etc. Affects the transmission distance is limited. The GPRS communication technology is mature, the network coverage is wide, it can be permanently online, according to the flow rate, the cost is low, and it is not limited by distance and space, which makes the application in the meter reading industry very suitable. GPRS network energy meter is a combination of GPRS communication technology and meter technology. He combines three-phase multi-function energy meter and GPRS communication module to form an energy metering device with wireless network communication capability. The GPRS network energy meter consists of two parts: the base meter and the GPRS wireless communication module. 1. 1 base table The base table can realize the basic functions of the ordinary three-phase multi-function electric energy meter, and does not affect its use as a common multi-function electric energy meter without being connected to the GPRS communication module. It performs real-time sampling, processing and storage of AC analog quantity, and realizes energy metering, demand measurement, multi-rate, load curve calculation and storage, data freezing, event recording, multi-rate, etc., which can realize user pre-purchase electric control and load. Control, remote control and other functions. It has RS 485 communication interface, infrared communication interface and GPRS communication module interface to realize data reading and setting. The base table also has local LCD display, which can support local patrol and key display functions. 1. 2 GPRS communication module The GPRS communication module is the key node for data uploading of the GPRS network energy meter. As a separate module of the network energy meter, it can meet the technical requirements and transmission protocols of the user meter reading system without affecting the metering of the base meter, and realize the reliable data. transmission. The downlink communication between the GPRS communication module and the base table satisfies the DT / L645 multi-function energy meter communication protocol, and the uplink communication with the primary station satisfies the "Power User Information Collection System Communication Protocol" (Q / GDW 376. 1-2009) standard. The software and hardware design of the GPRS communication module is emphasized here. 2. 1 system block diagram The system block diagram of the GPRS wireless communication module is shown in Figure 1. The system includes: ARM microprocessor (LPC2138), GPRS module, FLASH and ferroelectric memory, infrared transceiver, RS 232 serial debugging interface, RS 485 communication interface, JT AG simulation interface, LED indication and power conversion. Figure 1 GPRS network energy meter system block diagram 2. 2 module function 2. 2. 1 microprocessor The 32-bit microprocessor LPC2138 based on the ARM7TDMI??S core is embedded with 512 KB of high-speed FLASH memory and 32 KB of RAM. It has abundant peripheral resources such as: 2 32-bit timers (with capture, Comparison channel); 2 10-bit 8-channel ADCs; 1 10-bit DA C; PWM channel; 47 GPIOs; 9 edge or level-triggered external interrupts; RTC with independent power supply and clock; (UART, I2C, SPI, SSP); contains vectored interrupt controller, configurable interrupt priority and vector address; on-chip boot loader, can be implemented in system/in-application programming (ISP/IAP), on-chip The PLL can achieve a CPU operating frequency of 60 MH z with two low-power modes, idle and power-down, and can be woken up by an external interrupt. 2. 2. 2 GPRS module Adopting the M580 z module produced by Shenzhen Youfang Technology, it integrates the T CP/IP protocol stack, has two communication links, one standard TT L serial communication port, a streamlined AT instruction set, and can realize modules through AT commands. Parameter settings and data transmission. The M580 is connected to the CPU via a serial port of TT L level. 2. 2. 3 memory Since the uplink communication with the primary station should meet the communication protocol of the power user's electricity information collection system! A type of data (real-time data), two types of data (curve data, statistical data), and three types of data (events) required to store the specification, especially the curve data requires a large amount of data to be stored, so a large-capacity FLA SH is used. Memory to store two types and three types of data. Since the ferroelectric memory can be erased without restrictions, it is used to store real-time data and setting parameters that need to be updated frequently. The interface between the memory and the MPU is the SPI interface. 2. 2. 4 serial interface and JTAG emulation port Local settings and maintenance of module parameters can be realized by using RS 232 serial port and infrared communication port. Among them, the RS 232 serial port can realize the monitoring of the status of the GPRS module, and can read and write the communication protocol of the power user information collection system through the RS 485 serial port! Data; JTAG emulation port for emulation and program programming of ARM processors. 2. 2. 5 LED indication The LED indicator is used to indicate the power status of the module, the module login status, network communication status, and power-on status. 2. 2. 6 three-phase electric energy meter The three-phase electric energy meter realizes the collection and calculation of electric energy, voltage and current data. It is connected with the MPU through a serial port, and the communication protocol satisfies the DT / L645 protocol. The module periodically reads the three-phase table data, including real-time data such as power, demand, voltage, current, etc., and converts the copied data and Store to meet the access requirements of the master to the module. 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