Alternative Strategies for Managing Virtual Circuit Failure and Recovery in Local Area Computer Networks

A virtual circuit (or path) is a full-duplex logical connection between two processes. Two varieties of idealized virtual circuits that differ in their reliability characteristics can be distinguished: simple virtual circuits and reliable virtual circuits. Simple virtual circuits have the basic characteristic that data are transmitted across the circuit with no errors as long as the circuit is operational; however, the circuit may fail at any time. Reliable virtual circuits transmit data reliably at all times, in spite of link or processor failures: any recovery and/or reconfiguration that takes place to reconstruct a failed circuit is totally invisible to the two endpoints; any recovery and/or reconfiguration of a failed endpoint (process or processor) is invisible to the nonfailed end. A simple uniform mechanism for managing simple and reliable virtual circuits and for coping with failures of virtual circuits in a local area computer network is described. The mechanism supports the movement of Virtual circuit endpoints to different machines (as part of reconfiguration following failure, for example), and is robust with respect to the failure of any of the software components involved in the establishment and management of simple virtual circuits.     

基于RTL8019AS的串口与以太网接口转换器的设计

随着网络的发展,以单片机为中心的数据采集、检测控制等系统接入网络共享信息已成为一种趋势,但由于单片机系统的RS-232串口与RJ45网络接口不兼容,使得单片机系统接入网络存在困难。文中提出了一种单片机RS-232串口与RJ45以太网接口转换器的设计方案,转换器总体结构由控制单元、网络接口单元、电源单元组成。还设计了每个单元的硬件电路,并给出了程序流程以及转换器的工作过程。该转换器成功应用于风机监测系统的改造项目。     

USB—RS232转换卡的设计与实现

与RS232总线的数据传输速率相比,USB的传输速率高达480Mb／s,因此很多计算机的RS232串行接口都被USB接Kr所替换,但是很多仪器仪表、控制终端、远程终端等设备的接口还是沿用RS232。为解决两个接口之间的转换,设计并研制了USB-RS232接口转换卡。从USB和RS232通信协议出发,详细介绍USB-RS232转换卡的设计原理,并以CH341T芯片为例,设计并制作了USB-RS232转换卡。利用研制的USB-RS232转换卡连接具有RS232接口的温湿度传感器,在运行监控程序后,传感器运行稳定,能正确显示温湿度数据,且表明该转换卡可成功地实现RS232接口与USB接口的转换。     

Peripheral interface standards for microprocessors

Interfacing a peripheral to a microprocessor requires a peripheral interface attached to the processor and a controller within the peripheral, with usually a transmission link in between. Universal and special interface circuits are becoming available for an easy interface with the various microprocessor peripherals. The use of programmable interfaces increases the flexibility of the interface, and standards are necessary for reaching high-volume production. Present standards include serial EIA RS232 and the recent Hewlett-Packard Interface Bus for measuring instruments. Four new standards developed and used at the Mini and Microcomputer Laboratory of Lausanne fill a gap at the following levels: 1) microprocessor data, address, and control bus, 2) parallel data transfer, 3) simple serial data transfer with handshake, and 4) serial bus for data exchange between terminals and processors.     

多接口协议转换器的设计与实现

随着工业控制的进一步发展,多个设备之间的信息共享和数据交换成为一种趋势,而目前常用的工控设备通信接口有RS-232、RS-485、CAN和网络,由于各接口协议不同,使得异构网络之间的操作和信息交换难以进行,通过多协议转换器可以将不同接口设备组网,实现设备间的互操作。本文介绍了以DS80C400微处理器为核心的多接口协议转换器的设计和实现。针对系统功能,着重对软件设计进行了分析。并提出利用JavaApplet和Socket（套接字）实现协议转换器的参数配置,该协议转换器已运用于某系统,试运行效果良好。     

Transistor failure by secondary breakdown

To solve the problem of transistor failures by transients in inductive load circuits, experiments are performed to monitor the voltage and current waveforms of such transients. It is concluded from this experiment that these failures are caused by secondary breakdown. A model of the local temperature rise is studied and shown to be the possible mechanism of secondary breakdown.     

基于AT89S52的水情遥测终端设计与实现

设计了一种基于单片机的低功耗水情遥测终端,实现多种水情数据的采集、处理和报送。终端采用AT89S52单片机作为硬件核心,由扩充存储器、实时时钟、键盘输入、液晶显示、串行通信、调制解调及太阳能供电等外围电路构成。同时具备数字和模拟数据采集接口,通过连接相应传感器,实时采集雨量、水位、闸位、流量、温度等信息,使遥测参数多样化。显示模块与按键配合,用于动态显示、设置参数及系统的检测维护。设计的RS-232通信接口,可连接SMS/GSM、GPRS、无线电台等通信模块,满足不同通信方式下的应用,提高了通用性。该终端在实际应用中亦能稳定可靠地工作,满足水情遥测的功能和性能等技术要求。     

基于PCMCIA接口的高速率串口扩展卡

由于串行总线速度不断提高,笔记本电脑上的RS 232接口已经取消。为了实现工控设备通过RS 232接口与笔记本电脑相连接的需求,利用笔记本上未经使用的PCMCIA接口进行扩展。选用OXCF950芯片,并利用该芯片内部的E2PROM对串口进行设置。给出了系统的实现方案,通过4片OXCF950芯片可扩展出4个独立的串口,大大提高了笔记本带外设的能力。由于串口的并行性,系统具有很高传输速率。     

串行光纤数据总线技术的开发研究

详细论述了所开发的串行通信链路的开发过程及设计方案。从光通信链路入手,在研究了相关串行通信接口协议的基础上,通过相关的发射和接收接口电路设计,开发了相应的光电转换接口模块,并对其进行了相关的基带传输性能测试和数据通信测试。测试结果表明,所开发的光通信设备可稳定工作在460.8 kb/s。该光电转换接口设备是为了配合用于小型无人直升机的光传数字舵机的验证而开发,它以光信号的形式传输飞控计算机至舵机的控制指令,并返回舵机位置传感器信号。飞控计算机端电气接口采用RS-232标准,舵机控制器端采用RS-485接口标准,通信波特率为9600 b/s。通过其在直升机贴地飞行光传操纵半物理仿真平台上的验证表明,所开发的光电接口设备兼容两种串行接口,能够满足验证工作的需要。     

微机在应变测量中的应用

微机在应变测量中的应用，采用上位机和下位机组合方式．上位机为一台ＩＢＭ－ＰＣ／ＸＴ微机，用于对数据进行后处理．下位机以Ｚ８０－ＣＰＵ为控制器，由传感器、转换器、接口及外设等组成数据采集器，实施对应变、压力和位移等参数的采集、显示和打印（即数据的预处理）．上位机和下位机之间的数据传输，采用串行的方式，通过ＲＳ－２３２接口完成．本文主要以应变的采集处理为例，介绍系统功能、硬件配置及软件设计．     

基于无线通信的脉搏信号采集系统

应用无线通信技术的脉搏信号采集系统减少了系统各部分间的电缆连接.分别以MSP430F2234系统级芯片和AT89S52单片机为主控芯片,nRF905无线数据传输芯片为核心,围绕计算机设计了一种无线脉搏信号采集系统,从系统的组成结构出发,分析了各个模块的基本功能及如何实现,给出了硬件和软件设计.该系统实现了人体脉搏信号的短程无线测量,具有体积小、重量轻、成本低、携带方便、应用价值高等优点,在实时医疗监护中具有重要的意义.     

高性能舰船姿态信息模拟器的硬件设计

介绍了一种全新高性能舰船姿态信息模拟器,实现了三种不同的对外通讯接口：网络、串行ＲＳ－４２２、自整角机或旋转变压器式模拟通道,分析了舰船姿态数据组在三种不同界面之间高速交换电路的可行性,并最终完成了ＰＣ机、单片机、模拟通道模块组之间实时信息传递的硬件设计。     

基于CAN总线的RS-232串口设备远程通信

阐述了CAN总线在232串口设备远程通信或自组网络中的应用．介绍了CAN到RS-232转换装置的软硬件设计方法。重点对软件设计中CAN波特率的设置、串口波特率的自动检测以及数据流控制等作了详细的叙述。     

Reliability challenges for copper interconnects

In the past few years, copper has been widely used as interconnect metallization for advanced ultralarge-scale integration (ULSI) circuits. Due to the unique chemical properties of copper compared to its predecessor, aluminum, different integration processes must be used for circuit fabrication, that is, the damascene versus reactive ion etch (RIE) process. This difference in integration processes introduces a series of reliability concerns for copper interconnects. After a brief comparison of copper and aluminum interconnects, this article discusses the impact of the differences in the material properties and integration process on reliability. Details are provided on two advanced metallization reliability failure mechanisms: electromigration and stress migration. For copper interconnects, the interface between the cap and the copper metal serves as the fast diffusion path. To improve copper interconnect reliability, development efforts have focused on suppressing copper or copper vacancy diffusion along the interface. Two copper interfaces, the copper/cap interface and the copper/liner (or diffusion barrier) interface, are critical for copper reliability. For commonly used liners, such as Ta/TaN, the copper/liner interface is relatively easy to control compared to the copper/cap interface. For dual-damascene copper lines, a copper via is used to connect the lower level to the upper level. Unlike the robust tungsten stud used in aluminum interconnects, the copper via has been identified as a weak link in dual-damascene copper connections; the majority of early reliability failures can be attributed to the copper vias. The three most critical process factors and elements affecting copper interconnect reliability are copper vias and interfaces and the liner coverage. Using a low-k dielectric with a copper interconnect introduces several new challenges to reliability, including dielectric breakdown, temperature cycle, and stability within packages. Extensive knowledge is urgently needed to understand these issues.     

Environmental degradation of utility power connectors in a harshenvironment

This paper reports on an investigation of the effects of a marine atmospheric environment on the performance of aluminum bolted, compression, and fired wedge power connectors. These connector types are representative of the three major connector technologies used in electrical distribution systems throughout the world. The atmospheric test site was situated on the seacoast in Daytona Beach, FL. The test specimens consisted of sections of aluminum and copper conductors joined together by a connector. The paper describes the performance and lifetime of the different connector types exposed to the harsh marine environment. Examinations of failed connectors revealed that failure in all three connector types was ultimately due to galvanic corrosion at the aluminum/copper interfaces within the connectors. The failure rate was largest for compression connections. Bolted connections failed somewhat less rapidly. The failure rate for fired-wedge connections was the lowest     

非线性设备与编辑录像机遥控部分的接口技术

从RS—232C，RS—422接口标准及RS—232C与RS—422的电平转换等方面详细地介绍非线性设备与编辑录像机遥控部分的硬件接口技术，给出了相关的电路原理图，指出了使用时的一些注意事项。     

光设备中嵌入式测控网络模块的设计与实现

文章提出了一种基于UIP（嵌入式传输控制协议／网际协议）协议栈的光设备中的测控模块的设计方案。测控模块作为低成本的测控网络接入方案，可以将具有RS-232／RS-485（串行通信接口）等接口的测控设备简单又直接地连接到局域网上，利用现有的丰富的局域网资源，组成一系列局域网的分布式测控系统。     

RS-232与CAN接口卡的设计与开发

与传统的RS-232总线相比,CAN(控制器局域网)总线是一个高速、长距离、多主、经济的网络系统,特别适用于实时系统。其易用性和低成本使得CAN在汽车工业和自动化领域得到广泛应用,因此设计高性能的RS-232与CAN总线的接口卡以代替传统的PC机的RS-232通信具有重要意义。文中主要分析了RS-232与CAN接口卡的工作原理;设计并实现RS-232与CAN接口卡的硬件接口电路;设计并调试了RS-232串口与单片机、单片机与CAN控制器之间的通信软件。     

Effect of System Processes on Error Repetition: A Probabilistic and Measurement Approach

This paper presents an approach to system reliability modeling where failures and errors are not statistically independent. The repetition of failures and errors until their causes are removed is affected by the system processes and degrades system reliability. Four types of failures are introduced: hardware transients, software and hardware design errors, and program faults. Probability of failure, mean time to failure, and system reliability depend on the type of failure. Actual measurements show that the most critical factor for system reliability is the time after occurrence of a failure when this failure can be repeated in every process that accesses a failed component. An example involving measurements collected in an IBM 4331 installation validates the model and shows its applications. The degradation of system reliability can be appreciable even for very short periods of time. This is why the conditional probability of repetition of failures is introduced. The reliability model allows prediction of system reliability based on the calculation of the mean time to failure. The comparison with the measurement results shows that the model with process dependent repetition of failures approximates system reliability with better accuracy than the model with the assumption of independent failures.     

Metal problems in plastic encapsulated integrated circuits

The long-term reliability of plastic encapsulated integrated circuits in humid environments is ultimately limited by the effects of entering moisture. Degradation of device characteristics may be acceptable in some types of circuits, but catastrophic failures ("opens" and "shorts") are certainly not acceptable. Catastrophic failures can occur in a) the metalization used on the silicon chip itself, b) the internal wires, beam leads or frames, and c) the interfaces between these parts (and others) used in making a complete package. Entry of moisture permits electrochemical corrosion or deplating and replating of metals. This occurs under operating conditions, accelerated by externally applied potentials, and also in the unoperated condition due to EMFs produced by couples between dissimilar metals or by built-in potentials of p-n junctions. Choice of metal systems, platings, and passivation geometries determine the useful life and modes of failure of plastic encapsulated integrated circuits exposed to moisture.