ZigBee is an emerging IEEE 802.15.4 short distance, low-power wireless communication technology, mainly for automatic control and remote control, can be embedded in various devices, ZigBee technology can use very little energy Communication communication between thousands of tiny nodes is communicated with each other, and the radio wave data is passed from one network node to another, and the communication efficiency is very high.
CAN (Controller Area Network, CAN) is an ISO International Standardized Serial Communication Agreement, which is developed by Bosch, Germany, Germany, and the CAN bus has become a standard bus for embedded industrial control LAN, which is widely used in industrial automation, medical equipment. Car and other aspects.
1. Systematic basic composition and working principle
1.1 system composition
Combined with the special circumstances of coal mine applications, the structure of the wireless communication system in the coal mine is shown in Figure 1, which consists of the upper machine, the communication interface, and the CAN bus, the ZigBee communication base station, and the ZigBee communication terminal 5, as shown in Figure 1. .
Be
1.1.1 CAN bus hardware composition
The CAN bus is connected to the 120 Ω termination resistor twisted pair using both ends of the communication interface to the host computer, and is connected to the respective ZigBee communication base stations below the well. When the distance is greater than 10 km, increase the Canbridge bridge in a suitable location, changing the topology of the network, increasing the power of the connection device.
1.1.2 ZigBee Communication Base Station
The communication base station is divided into the CAN node, the microcontroller, the ZigBee node, as shown in Figure 2.
Be
The CAN node consists of a CAN controller, a CAN driver, and the photoelectric isolation module 3, and the CAN controller module selects TM320F2812, wherein the CAN controller is integrated, providing a complete CAN protocol. The transceiver controller uses PCA62C250 produced by PHzlzps. The PCA62C250 is isolated from the TMS 320F2812 using the 6N137 photocoupler to achieve electrical isolation of each CAN node.
ZigBee can be performed on 368 MHz, 915 MHz and 2.4 GHz. Due to the special structure and material composition of the coal mine roadway, the decay in the roadway, the degree of interference, the higher the degree of interference, the smaller the interference, so the frequency band of 2.4 GHz is selected, using ChipCon The company's CC2420, CC2420 is a low-power monolithic integration of the IEEE 802.15.4. Work on 2.4 GHz free frequency band. [Page]
1.1.3 Move communication terminal composition
As shown in Figure 3, the ZigBee communication module selects the CC2420, the voice processing module is responsible for the digital-to-mode conversion of the row voice, the LCD screen is interactive with the keyboard, and the Mike is responsible for the collection of voice, the speaker is responsible for the playback of the voice, the power supply can be charged.
Be
1.2 Working principle
There are 4 key steps in the system, as shown in Figure 4.
(1) The ZigBee mobile terminal is brought into the laneway by the staff, including the terminal address and the data package to hold hands with the zigbee communication base station with the ZigBee communication base station.
(2) The ZigBee base station receives the radio frequency signal to obtain the address and data information of the packet, as well as the antenna signal parameters, forward to the CAN bus.
(3) The CAN bus is sent to the data parsed by the MCU-treated ZigBee base station to the host computer, which contains the ID number, data and antenna signal parameters of the mobile ZigBee terminal.
(4) The upper computer software parses the data sent by the CAN packet. If there is no call, register and manage the position, power, signal, etc. of the ZigBee communication terminal, etc.. If the ZigBee terminal calls other terminals, the background software is routing, and the routing is established with the call terminal, and the routing is established, voice data transmission, complete voice communication.
1.3 host computer software
The host computer is used. NET platform development, database adopts SQL2008, the entire software module is shown in Figure 5.
Be
2, conclusion
This paper provides a newer technology implementation relative to the current coal mine has been applied in the coal mine. ZigBee has a low cost, reliable data transmission, low power consumption, and node communication settings that are easy to configure, safe, and technology relatively mature. It is proven that the system better meets the function of the downhole wireless communication.
Be
Be
Reprinted from -Wiku Electronic Market Network
Our other product:
