The Design Of Toxic And Combustible Gas Alarm System To Closed Welding Field

Welding was widely used in the fields of mechanical and electron,owing to its reliable and efficient joining. The welding process accompanies with series of complex physical and chemical metallurgy actions, the toxic gas is created, and when the air liquidity was weak, the toxic gas which was up to higher concentration damaged the welder and company benefit, So the toxic gas alarm system designed was important to control the toxic gas concentration in welding site.The thesis designed and made the Digital Signal Processing and the Can Bus based distributed toxic/combustible gas monitoring network system, which can monitor reference toxic/combustible gas on-line and real-time on these occasions.This Paper first investigates the Present situation and development of gas alarm Products, compares advantages and disadvantages of all kinds of gas alarm Products,studies the communication Principle of CAN bus. According to the design requirements of gas alann,the scheme based onCAN bus is Proposed.Secondly, the hardware design of the master controller and toxic/combustible gas detector is introduced in detail in this PaPer. TI company'DSP TMS320F2812, a high Performance MCU which has enhanced CAN controller, is used in the master controller as the center controller. The design of CAN communieation module is completed by using MCP2551 as CAN bus transeeiver. Information displaying and Parameter setting are realized by a LCD which has the touch sereen. Inaddition, the master controller also ineludes the Power conversion and detection module, sound and light alarm, realtime elock, extended 256kb ram and256 kb flash etc. Microchip company'PIC16f877A, high performance and low cost Single-Chip Microcomputer, is used in Gas detector as MCU. The design of CAN eommunieation module is completed by using MCP2510 as CAN controller and MCP2551 as CAN bus transeeiver. Furthermore, the gas detector also contain gas sensor signal adjust circuit, displaying, infrared receiving module, etc.Thirdly, the software design of the system is introdueed in detail. According to the analysis of function of the system and the basic requirements of task decomposition, the software of the system is compartmentalized into several modules of function such as Monitor Mutton, LED Display, Real-time Clock, CAN receiving and transmitting etc. The flow chart and some part software are introduced to reference module. Last, the drawing step of schematic and PCB by Protel DXP 2004 was introduced briefly. Electromagnetic Compatibility in the design of circuit is introduced in detail, such as the design of PCB, compenents placing, choose of isolation components etc.