基于RS485的多点传感器采集系统设计

发布时间：2018-07-16 22:42

【摘要】：在目前的工业现场控制、物联网、石油勘探、多点远距离监控等领域中,常采用RS485总线通信方式,这主要是因为RS485总线通信具有电路设计简单、可靠性高、抗干扰能力强、通信速度快及支持多点远离等特点。其次是总线通信控制芯片价格便宜,因此能极大地节约系统的设计成本,所以其广泛地应用于生产生活中智能监测控制的各个领域。本文是基于RS485总线来实现多点传感器数据的采集。首先从系统整体结构出发,从理论上分析确定系统所需功能指标,然后根据指标要求设计系统硬件电路和软件。本论文主要工作包括:(1)建立RS485总线在4种应用中电缆传输等效电路模型,测试3种485芯片其传输距离、通信速度和带负载能力三者之间的关系,根据测试结果选定芯片型号;(2)理论上分析传输线的反射过程,改进了电路结构模型,仿真验证了RS485总线通信中匹配电阻对降低信号反射的作用;(3)设计了主从机硬件电路模块,其中主机电路由中央控制芯片、USB控制电路、RS485接口电路构成,从机电路由中央控制芯片、RS485接口电路、环境数据采集电路、图像获取电路等组成。软件设计主要包括:上位机软件、RS485通信程序、USB驱动程序、传感器控制程序等部分。系统软硬件设计完成后,首先对软件中所采用的CRC(Cyclic Redundancy Check)校验码计算方法进行时间复杂度实验,并与其它两种方法做对比,根据实验数据结果说明该方法的优点及前期选用依据。然后对系统各模块进行功能调试,最后进行系统联调实验。实验测试得到系统基本达到了预设的功能指标。本文的设计使用上位机管理软件配合硬件系统,可广泛地应用于办公大楼、学生宿舍、智能生活小区、医院等人员出入的地方,整个系统可靠性高、操作简单、使用方便、可扩展性强,具有实际应用价值。
[Abstract]:At present, RS485 bus communication mode is often used in industrial field control, Internet of things, petroleum exploration, multi-point remote monitoring and so on. This is mainly because RS485 bus communication has simple circuit design, high reliability, strong anti-interference ability, etc. Communication speed and support for multi-point distance and other characteristics. Secondly, the bus communication control chip is cheap, so it can greatly save the design cost of the system, so it is widely used in various fields of intelligent monitoring and control in production and life. This paper is based on RS485 bus to achieve multi-sensor data acquisition. Starting from the whole structure of the system, this paper analyzes and determines the required function index of the system theoretically, and then designs the hardware circuit and software according to the requirement of the system. The main work of this thesis is as follows: (1) the equivalent circuit model of cable transmission based on RS485 bus in four kinds of applications is established, and the relationships among the transmission distance, communication speed and load capacity of three kinds of 485 chips are tested. According to the test results, the chip model is selected; (2) the reflection process of transmission line is analyzed theoretically, the circuit structure model is improved, and the effect of matching resistor on reducing signal reflection in RS485 bus communication is verified by simulation. (3) the hardware circuit module of master and slave computer is designed. The host circuit is composed of RS485 interface circuit, RS485 interface circuit, environment data acquisition circuit, image acquisition circuit and so on. The software design includes: PC software RS485 communication program USB driver, sensor control program and so on. After the software and hardware design of the system is finished, the time complexity experiment of CRC (cyclic redundancy check) check code calculation method used in the software is carried out, and compared with the other two methods. According to the experimental data, the advantages of the method and the basis of its early selection are illustrated. Then every module of the system is debugged, and finally the system adjustment experiment is carried out. The experimental results show that the system basically reaches the pre-set function index. The design of this paper uses the upper computer management software to cooperate with the hardware system, which can be widely used in office buildings, student dormitories, intelligent living quarters, hospitals, etc. The whole system has high reliability, simple operation and convenient use. It has strong expansibility and practical application value.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP212

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