工业网络中上级机与下级机之间的通信

工业网络常见形式有两种：集散控制系统（DCS）和现场总线控制系统（FCS）。它们都采用分层控制。下层网络，主要由单片机，PLC和智能仪表等构成，完成前沿控制任务。上层网络主要由PC机和工业控制机组成，完成集中操作和管理的任务。本文介绍PC机与单片机之间的通信方法，以完成工业网络中上扭机与下级机之间的通信。单片机选用使用面较广的89C51单片机，PC机中则使用应用广泛的VB6．0编程。     

PC机与多台单片机通信构成小型集散控制系统

介绍采用一台工业PC机与多台单片机通信组成集散控制系统的方法。单片机作为下位机,完成对现场控制参数的采集并发出控制信号;PC机作为上位机,完成各种复杂算法的运算并将运算结果传送给下位机。此种控制方式充分利用了PC机与单片机的优势,对多台退火炉的集中温度控制是非常适用的。     

DCS内PC机与单片机的通信

集散控制系统(Distributed Contro1 System,简称DCS)一般采用分散控制,分级管理和集中操作的设计原则.在集散控制系统(DCS)中,要确保数据、命令在各层次间、各计算机间快捷、正确地传递.系统中的通信是至关重要的.本文介绍作者在DCS中采用的PC机与单片机之间的通信方法.单片机选用使用面较广的MCS-51单片机,PC机中则使用应用广泛的VB6.0编程.     

DCS内PC机与单片机的通信

集散控制系统（Distributed Control System,简称DCS）一般采用分散控制,分级管理和集中操作的设计原则。在集散控制系统（DCS）中,要确保数据,命令在各层次间、各计算机间快捷、正确地传递。系统中的通信是至关重要的。本介绍作在DCS中采用的PC机与单片机之间的通信方法。单片机选用使用面较广的MCS-51单片机,PC机中则使用应用广泛的VB6.0编程。     

DCS内PC机与单片机的通信

集散控制系统 (DistributedControlSystem ,简称DCS)一般采用分散控制 ,分级管理和集中操作的设计原则。在集散控制系统 (DCS)中 ,要确保数据、命令在各层次间、各计算机间快捷、正确地传递。系统中的通信是至关重要的。本文介绍作者在DCS中采用的PC机与单片机之间的通信方法。单片机选用使用面较广的MCS - 5 1单片机 ,PC机中则使用应用广泛的VB6 .0编程。     

基于USB接口的步进电机控制系统

采用AT89S52单片机为核心的基于USB接口的步进电机控制系统,通过USB接口与PC机进行数据传输,实现上位机对步进电机的控制。利用VisualBasic6．0提供的通信控件编写上位机界面,完成PC机与单片机之问的通信,可精确的控制x向、Y向步进电机,实现直线或圆弧插补。     

分布式控制系统PC机与单片机多机通信抗干扰研究

从分布式控制系统结构角度出发,对工业现场环境中影响系统PC机与单片机多机通信的主要干扰因素进行分析,在此基础上,对分布式控制系统中的单片机系统、通信接口和通信电缆三个主要方面给出相应的硬件抗干扰设计,在软件设计方面,提出了各种行之有效的抗干扰措施.介绍了一种具体实用的通信接口电路,该电路采用光电隔离技术在实现系统RS232与RS485电平直接转换的同时又提高了系统的抗干扰能力.     

基于C51和PC的单片机系统界面设计

人机界面设计通常是单片机控制系统中一个必备而繁琐的工作。本文提出一种采用C51高级编程语言,利用串口通信,以PC机实现单片机控制系统中人机界面的方法。该方法有效地应用于单片机系统实验中。     

多路直拨电话计费系统的设计与实现

采用 PC机与多片 MCS- 51单片机组成系统 ,控制和管理多路直拨电话。其中 ,单片机为前台控制系统 ,PC机为后台管理系统 ,它们之间通过串行方式进行数据通信。     

串口通信技术在分布式控制系统中的应用

针对分布式控制系统中PC机与单片机之间多机通信这一关键技术,提出了一种在Windows环境下运用VC++6.0中MSComm控件来实现多机通信的可行方法,并简要介绍了VC++6.0的MSComm控件以及多机通信的原理,给出了进行多机通信的具体实现步骤与通信程序的主要代码.该方法简化了复杂的通信协议,使串口编程便于设计,形成一套经济可靠的数据采集、存储系统,可应用到多种分布式控制系统中.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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