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　　1 Overview

　　With the continuous development of wireless communication technology, in recent years, there has been a technology for wireless networking requirements for low-cost devices, called ZIGBEE, which is a close-range, low-complexity, low-power, low data rate, low-cost Two-way wireless communication technology, mainly suitable for automatic control, remote control field and home equipment networking.

　　Due to the superior characteristics of ZIGBEE, wireless networking based on ZIGBEE technology is a suitable means for implementing downlink channels. It is suitable for the networking of short-distance wireless networks, such as office buildings, office buildings, dormitory buildings, factories, etc. It is suitable for internal energy consumption monitoring and management systems, especially for some energy-saving management systems with difficult wiring renovation. in. And if it is combined with mature industrial Ethernet and GPRS/CDMA uplink channels, and the background management master station constitutes a complete collection and monitoring system, it can provide an effective solution for remote management. See Table 1 for comparison of ZIGBEE with other “last mile” technologies.

　　2 ZIGBEE technical features

　　The ZIGBEE protocol is based on the IEEE 802.15.4 standard. From the release of ZIGBEE V1.0 in 2004 to the latest version of ZIGBEE 2006 with the addition of the ZIGBEE-PRO extended instruction set, ZIGBEE functionality continues to grow. ZIGBEE has powerful device networking capabilities (see Figure 2) that support three main types of self-organizing wireless networks, namely Star, Mesh, and Cluster Tree, especially Mesh structure, with strong network robustness and system reliability. Compared with the commonly used short-range wireless communication technologies such as wi-Fi and Bluetooth, the main features of ZIGBEE are:

Figure 2 ZIGBEE network topology classification

 

(1) The working cycle is short, the power consumption of the transmitting and receiving information is low, and the RFD (Reduced Function Device) adopts the sleep mode, and can enter the sleep mode when not working.

(2) Low cost. By greatly simplifying the protocol (less than 1/10 of Bluetooth), the requirements for the communication controller are reduced. With the 8051 8-bit microcontroller, the full-featured master node requires 32KB of code, and the sub-function node has as few as 4 KB of code. .

(3) Low rate, short delay. ZIGBEE's maximum communication rate of 250 kb / s (working at 2.4 GHz), to meet the needs of low-speed data transmission applications. ZIGBEE's response speed is relatively fast, generally only 15ms from sleep to working state, node connection into the network only 30ms, further saving energy. In comparison, Bluetooth requires 3 to 10 S and Wi-Fi requires 3 S.

(4) Close range, high capacity. The transmission range is generally between 10 and 100 m. After increasing the RF transmission power, it can also be increased to 1 to 3 km. This refers to the distance between adjacent nodes. If the relay is used for routing and communication between nodes, it can reach several hundred meters or even several kilometers after expansion. ZIGBEE can be used in star, patch and mesh networks. A master node manages several child nodes, and at most one master node can manage 254 child nodes.

(5) High reliability and high security. ZIGBEE's Medium Access Control (MAC) adopts CSMA/CA collision avoidance mechanism, and reserves dedicated time slots for communication services requiring fixed bandwidth, avoiding competition and conflicts when transmitting data. ZIGBEE also provides a Level 3 security model that includes no security settings, uses access control lists to prevent unauthorized access to data, and uses Advanced Encryption Standard (AES) symmetric ciphers to flexibly determine its security attributes.

(6) Exemption from the license band. Direct sequence spread spectrum is used in the Industrial Scientific Medical (ISM) band of 2.4 GHz (global), 915 MHz (US) and 868 MHz (Europe).

 

3 ZIGBEE (Internet of Things) wireless network power management system architecture

Figure 3 shows the network topology of the ZIGBEE (Internet of Things) wireless network power management system. The whole network consists of four parts: metering, local wireless communication network, remote communication network and data exchange equipment. The entire network consists of meters, ZIGBEE collectors (responsible for communication with the instrument), ZIGBEE network terminals (responsible for interfacing with upper communication networks, such as industrial Ethernet, etc.), upper communication networks and data exchange storage devices. The networking mode generally adopted by ZIGBEE wireless communication management system is the mesh network of MESH. The MESH network can better guarantee the communication quality and ensure that the failure status of other nodes does not affect the communication status of other nodes.

Figure 3 Wireless network topology

4 ZIGBEE (Internet of Things) wireless network power management system solution
Ancorui's power management analysis system for production power management designed by Jiangsu Ankerui Electric Manufacturing Co., Ltd. is a power management system based on ZIGBEE (Internet of Things) wireless network. The whole system is used in networking. ZIGBEE and RS485 hybrid networking mode.
There are 8 centralized monitoring points in the whole plant area, which are located in the power distribution room, the production power cabinet, the air conditioning power cabinet, the exhaust fan control box and several lighting control boxes at the end of the power distribution. Each monitoring point is provided with one wireless ZIGBEE collector, and the electric energy meter at the monitoring point is communicated through the RS485 bus; the monitoring center sets a ZIGBEE network terminal, combined with the actual situation of the site and considering the reliability of the communication, Set up a few ZIGBEE relay routers in place. The networking diagram of the system is shown in Figure 4.

Figure 4 Schematic diagram of ZIGBEE (Internet of Things) wireless network power management system solution

　　The company verified the actual parameters of the ANEZB wireless ZIGBEE communication module by establishing a factory pilot project for the ZIGBEE (Internet of Things) wireless network power management system solution. Detailed parameters are shown in Table 2.

　　5 performance parameters

　　6 wiring method

　　6.1 ZIGBEE Collector

　　6.2 ZIGBEE network terminal

　　7 shape and installation size (mm)

　　7.1 ZIGBEE Collector

　　7.2 ZIGBEE network terminal

　　7.3 Installation method

　　Installed on 35mm standard rail