Design And Implementation Of Multifunction Ethernet Nodes In Coal Mine

The security during the process of coal mining is facing some serious issues. Onlinemonitoring technology for potential hazards in coal mining is urgently needed to be developedto reduce the probability of accidents.RS-485/CAN bus transmission is the common way to transfer the data for coalminemonitoring equipment, but it cannot meet the need for long-distance data transmission. It is abetter solution using Ethernet to transfer the observed data to the ground station. A dedicatedconversion node protocol should be set up to obtain protocol transformation capabilitiesbecause of the differences in communication protocols between Ethernet and the monitoringequipments. However, current conversion node can only transfer the data from RS-485orCAN to Ethernet. It is necessary to develop a multi-function conversion nodes to get universalconversion.Based on CAN, RS-485and TCP/IP protocols, our work is to develop a multifunctionconversion interface circuits according to the following three steps. Firstly, we completed thecommunication connection through network by selecting a high-performance8-bitATmega128microcontroller with a common Ethernet driver chip RTL8019AS designgateway and transplanting the embedded real-time operating system μC/OS-II, TCP/IPprotocol stack. Secondly, the conversion in protocol between RS-485and Ethernet could beaccomplished by coupling the RS-485bus protocol, the transmission format of the data,RS-485transmission function used in the receiving process and a transformation programbetween RS-485and TCP/IP. At last, based on the analysis of the CAN bus protocol, theprotocol conversion between CAN and Ethernet can be finished by formatting CAN packetdata to Ethernet data using interrupt handling and redesigning the CAN message object, sendpackets received messages and error handling. The multifunctional conversion between Ethernet and coalmine networks in our system worked well in experiment.Instead of transforming and promoting the original hareware or technology, the Ethernetcan be combined with the underground network using a multifunctional conversion node onthe basis of the original monitoring system with the common bus. This solution keeps thecontinuity of the products. Our design can be implemented extensively to coal mining bymerging the monitoring system and Ethernet TCP/IP network into a comprehensive controlledsystem.