论文总字数：20808字

摘 要

实。在电厂蒸汽品质监督中通常智能一台分析仪器就只能测量一路样品，而通常电厂的蒸汽检测点有多个，这样就需要多台分析仪，而对于连续生产来说，样品的变化率不会太高，故通常一台分析仪利用率不够高。而且一台分析仪造价十分昂贵，而且需要每台分析仪都需要把信号输出，这样需要多个信号接入点，这造成测量系统整体的复杂与昂贵。故本课题项目提出分析仪需要进行复用的方案并进行了放置于取样装置前端的六路智能多通道分配器的设计，从而将一台分析仪充分利用，让其能够分时复用来测量多份不同样品，这样极大降低原有蒸汽品质监测系统的复杂度而且降低未来需要拓展监测点时的成本，从而提高工厂的效益。

本文以电厂蒸汽品质监督中的取样装置的分时复用为课题背景，论述了用于工业现场的智能多通道样水切换装置的硬软件开发过程，主要完成课题中取样装置前的六路通道样水切换器部分的硬软件设计。首先介绍了当前用于现场监测仪表通讯的HART协议的发展现状。其次，介绍了硬件多通道分配器接收信号、处理与执行系统电路的工作原理，利用基于Web的在线电子线路设计应用立创EDA对转换信号、处理与动作、显示、通讯电路进行了原理图和印制电路板的设计并进行了仿真调试。另外，本文还介绍了串行模数转换MAX1241芯片、数模转换电路MAX538芯片以及模数混合通讯的HART技术在4-20mA电流环模拟通信中的应用，介绍了CP2102和单片机工作原理以及它们在通过USB与上位机通信中的应用。

对系统进行测试，测试结果表明该系统能够实现进样品通道的分时切换，显示屏实时显示与按键菜单选择，多通道分配器与中控室进行HART通信功能。本文最后提出了设计中的一些不足之处和对今后的一些要求。论文结尾附有多通道分配器HART通信电路的电路原理图和系统软件程序。

（宋体，小四）

关键词：单片机 蒸汽品质监测 HART通信

…(3-6个词)（宋体，五号）关键词之间分号空格分隔

（标题Times New Roman，四号加粗）

The hardware design of HART based multi-channel multiplexer device communicating with SCADA for sampling in power plant steam quality supervisory

Abstract

The high cost for power plant steam quality supervisory is mainly from purchasing enormous analysis equipment due to samples coming from various supervisory channels. Usually every channel needs a dedicated analysis equipment, which often isn’t made full use of as component change in the sample is relatively slow. In this project a multiplex using of analysis equipment is put forward which makes one analysis equipment been used to analyze samples from different channels, So the cost for purchasing new equipment for every channel is largely reduced and hardware system and software for multiplex device which use HART protocol to communicate with Remote Terminal Unit in SCADA(Supervisory control and data acquisition) system is designed. In the project test, the channels time-multiplexed analyzed for numerous samples in this multiplex device are 6.

This thesis introduces the hardware design of HART based multi-channel multiplexer device communicating with SCADA with the background of sampling in power plant steam quality supervisory, mainly complete the design of intelligent multiplex device for existing analysis equipment part in the subject. Firstly introduces the current development of HART protocol used in many fields and the future of industrial analog/digital signals’ fusion. Secondly, this thesis introduces the subject of multiplex system hardware circuit and the working principle of the 4-20mA remote control system and plate circuit design of each component designing D/A converted to HART module circuit and printed circuit board with online electronic design app(website) LCEDA(lceda.cn) and then do simulation test. In addition, this thesis also introduces MAX1241 serial A/D chip, MAX538 D/A chip, CP2102, HART superimposing module and single-chip microcomputer principle and electrical properties.At last, I also find something need to improve. In the end the paper with multiplex device circuit schematic diagram and printed circuit diagram and program.

（Times New Roman，小四号）

Keywords: Single-chip Microcomputer; Multiplexed-Analyzer; HART Communication

（Times New Roman，小四号。关键词之间分号分隔；最后一个关键词后不打标点符号。）

目 录

摘 要 I

Abstract II

目 录 II

第一章 引言 2

1.1概述 2

1.2 HART通讯的发展现状 2

1.3 本文的主要工作 2

第二章 工业现场HART通讯概述(一级标题三号宋体居中) 2

2.1 HART技术的概念(二级标题四号宋体加粗居左) 2

2.2 如何设计叠加了HART协议的4-20mA信号 2

2.2.1 数字信号叠加模拟信号的频率分类(三级标题小四号宋体居左) 2

2.2.2 HART协议的解调与分层数据 2

第二章 智能多通道分配器硬件电路设计 2

2.1系统总体设计方案 2

2.2数字与4-20mA转换模块设计 2

2.3 4-20mA叠加HART信号模块设计 2

2.3.1 HART协议信号产生电路设计 2

2.3.2主控部分电路设计 2

2.4串口信号转换电路设计 2

2.5印制线路板设计 2

第三章 智能多通道分配器系统软件设计 2

3.1系统软件总体结构 2

3.2系统子程序流程 2

3.2.1系统初始化子程序 2

3.2.2外部中断服务子程序 2

3.2.3定时器中断服务程序 2

3.2.4延时子程序 2

3.2.5 HART数据发送子程序 2

第四章 系统调试 2

4.1系统调试方案设计 2

4.2系统调试与结果 2

结语 2

参考文献 2

致谢 2

附录1：主控板电路图 2

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