With the rapid development of our country economy, the energy consumption increases dramatically. Although the energy production maintains a fast growth, this can only meet the 75% demand of energy consumption. The coal industry holds the pivotal status in the national economy development. In the sector of mining, it frequently suffers from the flood which is one of the five biggest geology disasters of coalmining industry, seriously restricting the healthy development of coalmining industry [1]. At present, with the increasing of the of coal mining depth, flood add more pressure to the coalmining, therefore to pre vent the flood, the monitoring of pressure in the process of coalmining becomes more urgent than ever.
At present more number of wires are used, In which it cannot be operated at high data rates. It cannot provide high speed network. It cannot connect more number of devices. It cannot measure all parameters simultaneously and there is no automation control. It has poor error detection and Confinement capabilities. It has low-integrity serial data communications bus for real-time control applications. Less number of network established among microcontrollers. The level of temperature, pressure and potential hazards in mines such as carbon monoxide, a toxic gas that can occur as a by product from combustion can be monitored mostly depends on the manual mode.
In this paper we the monitor Coalmining industry using CONTROLLER AREA NETWORK(CAN).When there is an abnormal condition of Pressure and Toxic gases then slave controller will send fault to master node .The master node send rectifying control to the slave node .The slave rectify the abnormality according to the condition. It is a high integrity serial data communications bus for real-time control applications. It can be Operated at data rates of up to 1 Mega bits per second (about 40 meters).It Has excellent error detection and confinement capabilities. Two-wire high-speed network system .link up to 2032 devices in this network. It provides 1Mb/sec speed between master and slave unit. It can used in even noisy environment. CAN is a broadcast serial bus standard for connecting electronic control units (ECUs).The first CAN controller chips, produced by Intel and Philips.
The CAN bus module consists of a protocol engine and message buffering and control. The CAN protocol engine handles all functions for receiving and transmitting messages on the CAN bus. Messages are transmitted by first loading the appropriate data registers. Status and errors can be checked by reading the appropriate registers. In coalmining, there may be a high pressure found. The CAN Slave detects the pressure level continuously and inform to the CAN Master. If the Pressure level exceeds the certain level, then the master CAN informs the Pressure level to the workers by activating the Pressure Alarm System.
Among potential hazards in mines are carbon monoxide, a toxic gas that can occur as a by product from combustion. The CAN Slave detects the CO level, if it exceeds the dangerous level, then it informs the number workers working in different Zone to the master Unit. The master Node immediately Closes the Precaution door according to the number users in each Zone. In coal mining, Fire has long been a concern for underground mine workers. A mine fire can occur at any time and can result in a partial or total evacuation of mine personnel and the loss of lives. Fires can grow rapidly. For this instance, the Master CAN will automatically detects the fire and makes the necessary action according to the fire level. With the progress of time and the development of technical, the application of wireless communication is getting more and more widespread.
The GSM network is quite mature after many years’ development, the coverage of which is also getting broader. People can carry on the long-distance monitoring through the GSM network, this does not need the staff to gather the data personally at present, by doing this saves manpower, physical resource and the financial resources, also it can real-timely gather the information of mine pit.
GSM is a digital motion communications net that develops rapidly recently, and it is one kind that stems from Europe's mobile communication technical standard. At present, China Mobile and China Unicom have a GSM net respectively; it’s the world biggest mobile communication network. GSM system has a good security ability, large network capacity, lots of SIM number, clear telephone conversation, not easily is disturbed stability, keen information, few dead angle telephone conversation, low power consumption and so on [3]. When compared to the traditional colony system, GSM network has the unequal superiority in wireless network coverage, in addition to the data transfer functions of GSM itself, enables the rapid application of wireless data.
SYSTEM MODEL OF CAN
The system model of the CAN based Network system consists of two nodes such as master node and slave node. Both nodes are connected through the CAN Module. The priority, at which a message is transmitted compared to another less urgent message, is specified by the identifier of each message.
Figure 2. Real-time data transmission
The priorities are laid down during system design in the form of corresponding binary values and cannot be changed dynamically. The identifier with the lowest binary number has thehighestpriority.
The CAN bus has two states: Dominant and Recessive. A dominant state occurs when the differential voltage between CANH and CANL is greater than a defined voltage (e.g.1.2V). A recessive state occurs when the differential voltage is less than a defined voltage (typically 0V). The dominant and recessive states correspond to the low and high state of the TXD input pin, respectively. However, a dominant state initiated by another CAN node will override a recessive state on the CAN bus.
CAN DRIVER
The MCP2551 is a high-speed CAN, fault-tolerant device that serves as the interface between a CAN protocol controller and the physical bus. The MCP2551 provides differential transmit and receive capability for the CAN protocol controller and is fully compatible with the ISO-11898 standard, including 24V requirements. It will operate at speeds of up to 1 Mb/s.
Figure 3.High-SpeedCAN Transceiver
PIC18F458 MICROCONTROLER
In our proposed work, we use PIC 18F458 Micro controller, it has the special feature of inbuilt CAN Module. PIC18f458 is 28/40-Pin High performance, Enhanced Flash Microcontrollers. It has High performance RISC CPU. It has Advanced Analog Features like 10-bit, up to 8-channel Analog-to-Digital Converter module (A/D).
It has Special Microcontroller Features like Power-on Reset (POR), Power-up Timer (PWRT) and Oscillator Start-up Timer (OST) Watchdog Timer (WDT) with its own on-chip RC oscillator. It has Flash Technology with Low-power, high-speed Enhanced Flash technology, fully static design and Wide operating voltage range (2.0V to 5.5V).
Figure 4. PIC18f458 Microcontroller.
ULN 2003
ULN 2003A/L is a high-voltage, high-current darlington arrays Ideally suited for interfacing between low-level logic circuitry and multiple peripheral power loads, the Series ULN20xxA/L high-voltage, high-current Darlington arrays feature continuous load current ratings to 500 mA for each of the seven drivers.
Figure 5.ULN 2003
SIGNAL CONDITIONING UNIT
LM324 which is a signal conditioning unit. This is the IC that the four operational amplifiers are housed in the one package. It is possible to work with the single power supply. It’s used as Sensor signal conditioner in our circuit.
Figure 6. Signal Conditioning Unit
GSM DATA ACQUISITION
The system uses the existing GSM network, transmitting data through mobile modules, and it has a dynamic real-time monitoring for the Pressure, temperature and the toxic gases like CO in the large area. Also it has high precision in collecting data. Use this system, users can monitor the real-time information in the coal mines. We used DKU5 data cable compactable NOKIA GSM mobile as a GSM device. The Microcontroller used in GSM Data acquisition is AT 89S52 AT commands are instructions used to control a GSM device. AT is the abbreviation of Attentions. Every command line starts with "AT" or "at".
Figure 7. GSM Data Acquisition.
The MAX232 device is a dual driver/receiver that includes a capacitive voltage generator to supply EIA-232 voltage levels from a single 5-V supply. Each receiver converts EIA-232 inputs to 5-V TTL/CMOS levels.
Figure 8. Serial data communication
The above figure shows the serial data communication in GSM data acquisition. This system uses GSM network to transmit data, no wire laying, broad network coverage, good signal quality and realizes wireless data acquisition.. Data acquisition transmission, memory are integrated. Low power consumption and only supply data transmission unit with the battery.
CODING
Slave
Figure 9. Coding for Slave
Master
Figure 10. Coding for Master
CONCLUSIONS
The security management system for coal mining in this paper adopted wireless communication technology and embedded system. The system uses the existing GSM network, transmitting data through mobile modules, and it has a dynamic real-time monitoring for the temperature, the pressure, fire, and toxic gases in the large area. Also it has high precision in collecting data. Therefore, it provides a guarantee for the safe production of the coal mine. The system was successfully developed to break the current coal mining information’s measurement model, and to realize the automation, and intelligent for measuring the information of temperature, the pressure, fire, and toxic gas like CO measurement. Also the system has high social value.
