MCS-51单片机串行口的一口多用

在介绍ＭＣＳ－５１单片机串行口的几种工作方式的基础上将其用于一口多用。     

"MCS-51单片机的内部结构"的教学特点

通过对社会需求、学生特点、教学内容等方面的分析,阐述了“MCS-51单片机的内部结构”这一教学单元的教学策略,提出了教学评价方法。     

MCS-51系统DA A指令浅析

本文就单片机的DA A指令出现的前提、指令的调整规则、指令的其它功能几方面进行了全面的分析。关于本指令的调整规则,文章采用了完全列举法进行了证明,并举例进行了验证;对于指令"减1"的功能,也详细进行了说明,同时给出了实例进行了验证。     

LONWORKS控制模块与MCS-51单片机的并行通信

介绍基于单字节并行通信技术 ,实现LONWORKS控制模块与MCS 5 1单片机之间的数据交换 ,给出了接口电路及相关程序。     

MCS-51的多任务系统设计思想在工程中的应用

利用多任务系统设计理念把设计需求作为多任务系统进程应用于工程设计中。抛弃系统时间片和系统进程管理机制。用简洁的系统进程来处理各需求中纷繁复杂的关系,从而简化构架设计,节约系统资源,缩短开发周期。     

Windows环境下利用多线程技术实现计算机与单片机的串行口通讯

基于 3 2位Windows98环境开发了计算机与单片机间进行串行口通讯的软硬件系统 ,其中采用了多线程技术模拟中断机制 ,并利用同步事件确保线程间资源共享的同步 ,从而有效地克服了传统串行口通讯中的迟滞性和不可靠性。     

I/A51 DCS系统在苯乙烯装置中的应用

介绍I／A51系统在苯乙烯装置中的应用，重点以一些典型控制回路为例描述系统的组态。     

远程I/O系统与DCS通讯的实现

远程I/O系统是一种新型的控制系统 ,近几年来发展迅速 ,应用量越来越大 ,技术上有一定的先进性。文中简要介绍了远程I/O的发展历史和技术特点 ,通过对德国p +f公司RPI和IS -RPI的具体分析 ,旨在使读者对远程I/O接口的技术特点有一个清晰的认识和了解 ,最后对p +f远程I/O接口与典型的DCS系统的通讯方式作了较详细的介绍。     

基于STC15单片机的ModbusI/O模块的设计

基于STC15单片机构建具有Modbus通信功能的8路I/O模块,给出模块的硬件组成和软件流程。该模块不仅满足基本I/O量数据的传输,而且利用STC15单片机的EEPROM可保存模块的重要参数。模块工作电压+3.3V,具有低功耗、低成本、经济可靠及电路设计简单等优点。测试结果证实:该模块能够正常稳定工作,并且实现了重要参数(如设备地址)的掉电保护。     

凌华科技推出分布式运动控制与I/O解决方案

凌华科技发布最新＂分布式运动控制与I/O解决方案＂,该方案整合具有实时性的专用型运动控制＂Motionnet＂以及I/O控制的现场总线-＂High Speed Link（HSL）＂,是市面上唯一可支持各大厂商伺服电机的分布式运动控制方案。     

基于51单片机的电镀废水处理控制系统设计

设计了电镀废水处理控制系统,本系统采用MCS-51系列单片机为控制核心,完成电镀废水处理控制系统的设计。详细介绍了利用A/D转换芯片TLC2543进行模数转换,三八译码器74HC138与89S51的接口电路设计,对硬件原理图和程序框图作了简洁的描述。     

计算机硬盘I/O操作性能测试与分析

首先将硬盘I/O操作过程抽象为一个M/M/1排队模型;然后利用排队系统相关理论对硬盘I/O操作响应性能进行理论分析,并推导出系统中平均任务数、队列中平均任务数以及平均响应时间等参数计算公式;最后通过对实际测试数据的计算分析,给出硬盘I/O操作对控制系统的实时运行的具体干扰力;并在文章最后提出一种解决措施。测试分析证明,硬盘I/O操作是高代价的操作,会影响控制系统的实时运行。     

Physical,optical and gamma radiation shielding competence of newly boro-tellurite based glasses: TeO2–B2O3–ZnO–Li2O3–Bi2O3

Herein, a traditional melt quenching method was utilized to synthesize glasses with a nominal chemical composition (80-x)TeO₂-xB₂O₃–5ZnO–5Li₂O₃–10Bi₂O₃: 30≤ x ≤ 80 mol%). The produced sample was coded as TBBZL30 to TBBZL80. X-ray diffraction (XRD) has been employed to test the amorphous nature of the synthesized samples. In the range of 200–500 nm wavelength, UV–Vis spectra for the glasses have been performed. Optical energy gaps ($E_{gap}$) have been determined based on the absorption measurements. With the help of ($E_{gap}$), refractive index (n), molar polarizability (α^M), metallization criterion (M^Cri.), molar refractivity (R^M), static dielectric constant (ε^Sta.), optical dielectric constant (ε^Opt.), reflection loss (R^L) and optical transmission (T^Opt.) have been calculated. For the fabricated boro-tellurite glasses, Phy-X/PSD was used to report some shielding factors for several energies between 15 keV and 15 MeV. The maximum attenuation for all samples took place at 15 keV and the mass attenuation coefficient varied between 52.309 and 57.084 cm²/g. The linear attenuation coefficient (LAC) results demonstrated that TBBZL80 has the highest attenuation than the rest of samples which is due to high content of TeO₂ (containing 80 mol% of TeO₂) whereas TBBZL30 has the lowest attenuation. The LAC for the fabricated samples varied between 230.160 and 351.064 cm-¹ at 15 keV. The minimum effective atomic number (EAN) occurred between 0.8 and 4 MeV and varied between 15.16 and 17.35 for TBBZL30 and 25.10–28.33 for TBBZL80. The addition of TeO₂ was found to enhance the EAN and improved shielding properties for the tested TBBZL glass systems.     

Fabrication and thermal expansion properties of ZrW2O8/Zr2WP2O12 composites

ZrW₂O₈/Zr₂WP₂O₁₂ composites were fabricated by sintering ZrW₂O₈–Zr₂WP₂O₁₂ powder mixtures at 1473 K for 1 h, and their negative thermal expansion properties were investigated. The relative density of sintered pure-phase ZrW₂O₈ was 72.3%, while that of the sintered composites was 88.4–92.3%. In the composites, the observed hysteresis in the thermal expansion data was small because of the small difference between the CTEs of ZrW₂O₈ and Zr₂WP₂O₁₂. The CTE of the composites was negative and increased with the Zr₂WP₂O₁₂ content. When the Zr₂WP₂O₁₂ volume fraction in the composites was increased from 0 to 75 vol%, the CTEs of the composites increased from ?9.1 × 10^?6 to ?3.1 × 10^?6 K^?1 and from ?5.0 × 10^?6 to ?1.9 × 10^?6 K^?1 over the temperature ranges of 323–373 and 473–673 K, respectively. In composites with Zr₂WP₂O₁₂ volume fractions of 0–25 vol%, the experimentally obtained CTE values were in good agreement with the calculated values obtained by assuming mixed law behavior.     

Thermal expansion and mechanical properties of phenolic resin/ZrW2O8 composites

Phenolic resin/ZrW₂O₈ composites were successfully fabricated and their coefficient of thermal expansion (CTE) as well as mechanical properties was investigated. The CTE of the composites decreases from 46 × 10^–6 to 14 × 10^–6 K^?1 when the ZrW₂O₈ volume fraction increases from 0 to 52 vol %. The CTE of the composites is analyzed by some theoretical models; Schapery's upper bound provides the best estimate of the reduction in CTE. The Barcol hardness of the composites increases with an increase in the ZrW₂O₈ volume fraction. The bending strength of the composites with 19–25 vol % of ZrW₂O₈ fillers shows a maximum value of 130 MPa, which is 45% larger than that of phenolic resin without fillers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

钢丝帘布压延机分布式I/O站改造

RODOLFO钢丝帘布压延机采用BK3100总线联结器，I／O从站采用插拔式连接、垂直悬挂安装，其相邻模块间以簧片接触，工作中由于机器振动经常发生通讯故障，工作稳定性差。采用西门子IM153—2总线联结器进行改造，通过修改组态和I／O地址，在不更换原电器箱和尽可能小地改动原程序的情况下，使压延机不再发生因通讯故障而停机的现象。     

Quantitative Analysis of the Parameters Affecting In-Cabin to On-Roadway (I/O) Ultrafine Particle Concentration Ratios

Given growing concerns over the observed relationship between ultrafine particles and adverse human health effects, there is a major need in the community performing human/animal exposure studies for methods that can be used for the generation of high concentrations of ultrafine particles (<100 nm) with controllable compositions. The Palas spark discharge generator (Palas GFG 1000) is commonly used to generate “soot-like” particles for such studies. However, before such methods can be used routinely in the lab, it is important to assess the chemical variability and reproducibility of the ultrafine particles produced using such techniques. The goal of this study involves performing the on-line assessment of the chemical variability of individual ultrafine and fine (50–300 nm) particles produced by a Palas generator. The aerodynamic size and chemical composition of ¹²C and ¹³C elemental carbon (EC), composite iron–carbon (Fe-¹²C), and welding particles were analyzed using aerosol time-of-flight mass spectrometry, and in general highly reproducible single-particle mass spectra were obtained. When using pure graphite (¹²C) electrodes, EC particles were produced with sizes peaking in the ultrafine mode and 96% of the mass spectra containing distinct C_n ⁺ (n = 1–3) envelopes at m/z 12, 24, and 36. In contrast, the size mode of the particles generated from isotopically labeled ¹³C graphite electrodes peaked in the accumulation mode, with 73% of the particles producing EC carbon ion cluster patterns at m/z 13 (¹³C⁺), 26(¹³C₂ ⁺), and 39 (¹³C₃ ⁺), with additional organic carbon species at m/z 15 (CH₃ ⁺), 27 (C₂H₃ ⁺/CHN⁺), 43 (C₃H₇ ⁺/CH₃CO⁺), m/z 58 (C₃H₈N⁺), and 86 (C₅H₁₂N⁺). Observed differences between the ¹²C and ¹³C particle spectra are most likely due to their different surface properties, with ¹³C particles more effectively adsorbing semivolatile organic species originating in the particle-free dilution air. Homogeneous metal particles were also generated from Fe-¹²C and welding rods with almost all (92% and 97%, respectively) of the spectra showing reproducible Fe/Mn/Cr and Fe/¹²C ion ratios.