毕业设计（论文）-基于Modbus协议的温度测控节点的设计.doc

基于Modbus协议的温度测控节点的设计
摘要
在机械、化工、纺织等行业,随着生产规模的不断扩大,以及对生产过程集中监控的迫切要求,现场总线技术应运而生,并成为了当今测控领域研究的热点之一。Modbus协议作为现场总线的一种,以其开发成本低,简单易用等诸多优点己被工业领域广泛接受。温度作为工业中重要的测量参数之一,本课题选择了温度作为测量的对象,并设计了基于Modbus协议的温度测控节点。
本设计采用TC1047A传感器采集现场温度,由STC12C5A60S2单片机进行AD转换和Modbus协议通讯。通讯的物理层采用RS485接口,并增加了光电隔离、抗雷击和短路保护等功能。最后实现了单个节点和PC机的Modbus协议通讯,并通过控制蜂鸣器和继电器来模拟工业现场控制。本文分别从硬件和软件上阐述了该温度测控节点的实现方法。
关键词温度测控 Modbus协议 RS485 STC12C5A60S2
The Design of Temperature Measuring and ControllingNode Based to Modbus Protocol
ABSTRACT
With the continuous expansion of production scale, and the urgent requirements in centralized monitoring of the production process in mechanical, chemical, textile and other industries. Fieldbus technology came into being, and e one of hot research field of measurement and control today. As one of field bus, Modbus protocol have been widely accepted because of low development cost, easy to use and many other advantages in temperature is one of the important parameters measured in industry,so it has been chosen a measurement of the object,temperature measurement and control nodes has
been designed based on Modbus protocol.
This design uses TC1047A sensor to collect on-site temperature,AD conversion and Modbus munications can be done by STC12C5A60S2 physical layer munication adopts RS485 interface, and have optical isolation, anti-lightning and short circuit protection in addition. Finally, achieved the Modbus munication between a single node and the PC, and simulate industrial control by controlling the buzzer, and relay. This paper describes the implementation of
temperature control node from hardware and software.
KEY WORDS Temperature Monitoring Modbus protocol RS485 STC12C5A60
目录
中文摘要 Ⅰ
英文摘要 Ⅱ
1 绪论 1
2 设计方案 3
方案概述 3
方案论证 3
通讯可靠性 4
温度检测电路选择 4
系统电源稳定性 5
3 硬件电路设计 6
最小系统电路 6
温度检测电路 6
电源电路 7
报警控制电路 9
通讯电路 10
显示电路 13
硬件抗干扰的设计 14
4 MODBUS协议概述与应用 16
MODBUS协议概述 16
4