Preface: China is a big country of coal mine, a large number of coal resources are hidden under the ground, the underground operation is inevitable, so how to ensure safe production, smooth coal mining has become a research focus of many coal mine safety workers. Many facts show that the annual coal spontaneous combustion event is a major disaster in coal mine, not only easily cause the loss of expensive equipment, but also may cause casualties. Goaf is the main area of coal spontaneous combustion, so early monitoring is very important. At present, temperature measurement method is the most commonly used and direct monitoring technology of spontaneous combustion. Haiwell digital temperature module H32DT can measure the temperature of 32 regions, with the disconnection alarm, and it has been widely used in the coal mine temperature measurement industry. According to the needs of temperature monitoring in goaf, the temperature monitoring system of goaf is designed by using ZigBee technology, programmable control technology, temperature sensor technology and database technology, which are composed of Haiwell host PLC , H32DT module and H01ZB module.
Key word: Haiwell domestic PLC, H32DT module, H01ZB module, coal mine temperature measurement
1、Introduction of temperature measurement network in coal mine
2、The main hardware of system
l Haiwell host PLC
Haiwell host PLC has two built-in communication ports, which can be expanded up to five communication ports. And each port not only can be used for programming and communicating, but also all of them can be used as masters or slaves. Haiwell host PLC supports the networking ways of 1:N, N:1, N:N and a variety of man-machine interface and configuration software. It also can connect to network with any third-party equipment which has communication function. (such as inverters, instruments, barcode readers, etc.)
l Haiwell digital temperature module H32DT
H32DT (32—channel temperature measurement module) temperature range: -55 ° ~ 125 °, digital chip determines the temperature, the highest measurement accuracy is 0.0625, display accuracy is 0.1, and the collected temperature value is no error, low cost. H32DT can be used as extension module of any host PLC, and it has one built-in RS485 communication port which can be used as remote IO module; 24VDC external power supply. H32DT can be used in a wide range of temperature measurement, such as industrial environment of coal mines, tunnels. Each channel can be connected to 16 sensors, one single module can be collected 32-channel temperature values.
l H01ZB module and PC2ZB module
PC2ZB is an extension module for wireless communication on the PC. Through this module, the upper PC with HaiwellHappy programming software can connect with host PLC which has H01ZB module for online and read-write operation in wireless way. The Modules are simple and convenient to use, no need to configure the zigbee parameters, toggle the DIP switch of the modules can easily set up the network. The modules which are based on the retransmission mechanism, add a response retransmission mechanism in the application layer to further improve the stability of communication.
3、Part of the program description
l Haiwell host PLC has two built-in communication ports with RS232 and RS485 can connect with the upper PC to read the temperature data of the coal mine site, to understand the situation in a timely manner, once the temperature exceeds the warning value, it will make the right processing in a timely manner to avoid unnecessary loss of property and casualties.
l Underground and ground wiring is difficult, and once appear the problems such as aging line or break line, it will be difficult to troubleshoot the problems, and you must spend a lot of time to deal with the line problems, which will make the site temperature without monitoring for a long time. This system uses the HO1ZB and PC2ZB module of Haiwell to set up a wireless communication network, in the site environment without change, it will not appear the situation of communications disconnection, completely solve the line problems.
l Using the H32DT module, one module can monitor the temperature of the 32 regions, the cost is low; the module itself comes with disconnection alarm, communicates steadily; The module uses communication to read the DS18B20 data, digital chip determines the temperature and high precision. The module has one RS485 communication port, when the temperature measuring point is far away from the host PLC, you can use the module as a remote module to reduce wiring, it is conducive to measure the multiple temperatures of coal mine underground.