Design Of Multi-sensor Acquisition System Based On RS485

RS485 bus communication is widely used in the current industrial field control,Internet of things,oil exploration,multi-point long-range monitoring,and etc.It has the characteristics of simple circuit design,high reliability,strong anti-interference ability,fast communication speed and multi point support.In addition,the bus communication control chip is cheap,which can greatly save the system design cost.Thus,it is widely used in various intelligent monitoring fields in production and life.The paper is based on the RS485 bus to achieve multi-point sensor data collection.Firstly,in terms of the whole structure of the system,the required functional indexes of the system were determined by theoretical analysis,and then the hardware circuits and software programs are designed.The main work of this thesis includes:(1)the equivalent circuit model of the wire transmission in the four types of applications of the RS485 bus is established,the relationship of transmission distance,communication speed and load capacity among the three types of 485 chips is tested,and the chip models is selected according to the testing results;(2)the reflection process of the transmission line was analyzed theoretically,the circuit structure model is improved,and the functions of the matching resistance in the RS485 bus communication to reduce the signal reflection is simulated and verified;(3)the host and slave hardware circuit modules are designed.The host circuit consists of central control chip,USB control circuit,and RS485 interface circuit,and the slave circuit includes central control chip,RS485 interface circuit,environmental data acquisition circuit,and image acquisition circuit.The software design mainly includes host computer software,RS485 communication program,USB driver,and sensor acquisition module.With the design of the system combined hardware and software completed,the time complexity experiment based on the CRC check cede is firstly carried out.Compared with other two methods,the merits and its basis for early selection is stated according to the experimental results,then the function debugging of the modules in the system is made,and finally the joint experiment of the system is taken.The experimental results show that the system basically reaches the presupposed goals.The host computer management software with the hardware system is used in this work,which can be widely applied in office buildings,students' dormitories intelligent living area,hospitals and other places.In conclusion,the whole system has the advantages of high reliability,simple operation,simplicity of operator,strong expansibility,and practical application value.