LabWindows/CVI与PLC的MPI通信研究

S7系列PLC与虚拟仪器开发软件Lab Windows/CVI之间可通过MPI（多点通信接口）网络实现可靠、高速的数据通信,从而完成复杂的工业现场控制和监测任务.本文阐述了Lab Windowsv/CVI与PLC之间MPI网络通信实现方案,结合应用实例介绍了软件接口开发的关键技术,并通过所设计的实验测试了两种不同硬件连接方案的通信速度.此研究对此类MPI网络通信开发应用具有指导意义.     

MPI总线技术在三钢炼钢厂的应用及现状

MPI(Multipoint interface)总线技术是西门子开发基于RS485的一种多点通信的接口技术,目前为西门子内部协议,适用于西门子PLC的总线连接技术。MPI是SIMATIC S7多点通信接口,是一种适用于少数站点间通信的网络,多用于连接上位机和少量PLC之间近距离通信。MPI总线是一种方便、可靠、廉价的中小型网络通信技术,在各行业有着广泛的应用。叙述了MPI总线技术通讯方式以及在三钢炼钢厂实际应用中常见的故障进行分析。     

LabWindows/CVI与西门子PLC的三种数据通信方式研究

针对LabWindows/CVI虚拟仪器测试软件开发平台与S7-300系列PLC通过MPI、IE以及OPC 3种数据通信方式建立相应可靠的连接过程以及实时数据通信的应用场合和具体实现方法进行了研究实验,并给出建立连接通信的具体步骤和部分参考示例代码以及重要操作函数的配置使用方法,具有很好的工程应用价值,并依次完成了3种数据通信方式下LabWindows/CVI对西门子CPU 314C-2DP下位机跑马灯程序的实时监控实验;经实验证明3种数据通信方式实时、稳定、可靠,可以根据不同实际测控系统应用需求选择使用。     

基于MPI网络的PLC饮料生产线监控系统

介绍了MPI网络技术和组态软件WinCC在饮料生产线上的应用,实现了多台PLC的组网、主从站PLC之间的通讯.系统通过装有WinCC的工控机上监控不同的生产线,并通过MPI网络对两台S7-300 PLC进行控制.PLC之间通过MPI总线相互通讯、协调控制,各处理器既能独立工作,又能相互联系,真正实现了集中管理、分散控制.     

基于虚拟仪器的立式电泳生产线监控系统

根据电泳涂装生产车问的布局结构及工艺要求,构建基于DH+的PL.C控制网络.开发基J.于LabWindows/CVI的实时监控系统.系统通过RSI,inx C SDK提供的库函数,实现LabWindows/CVI与ABRockwell公司SLC500型PLC的通信.将采集的数据进行处理后实现对生产线的实时显示、控制、报...     

计算机与数字示波器通过USB通信的软件设计

计算机采用NI公司的Lab Windows／CVI开发平台，利用软件试验的方法，得到了能够实现数字存储示波器通过USB接口与计算机通信的正确方法，并给出了软件设计实例及相应的解释。计算机与数字示波器之间通信的实现在工程研究和应用中有较大的实用价值。     

工控机模拟基于MPI协议的人机界面与PLC通信

文章通过数据采集、分析的方法,解析了MPI协议关键报文格式,可用于实现上位机、现场设备与支持MPI协议的CPU之间的通讯,从而提供了一种高效率低成本的通信方式。此外,通过协议分析,文中用串口通信实现了工控机模拟人机界面（HMI）与PLC基于MPI协议的通信。     

基于Linux的人机界面可重构通信设计与实现

人机界面在工业控制领域有很大的应用空间,由于PLC厂家众多且通信协议互不兼容,因此开发一种占用最少量资源但能实现最多种通信协议的人机界面产品具有重大意义。通过对松下等PLC串口通信分析,设计了一种基于Linux操作系统的可重构通信方案,为人机界面串行通信预留软件接口,实现了人机界面与多种PLC通信互连。     

利用MPI接口实现工控机和PLC之间的快速通信

本文主要介绍了利用VC++实现PLC与上位机之间的通信,并对其组成的MPI网络作了软硬件上的分析.     

基于VISA库的串行通信技术

介绍了VISA库的I／O接口软件在串行通信中的应用，并以MODBUS通讯协议为例在LabWindows/CVI开发平台下提出了采用仪器驱动程序方式实现通信的具体方法。     

MPICH2-CMEX:可扩展消息传递接口实现技术

在大规模并行计算系统中,为了更有效地利用系统的并行性,实现一个高性能、可扩展的MPI系统是非常重要的。CMEX是无连接模式的用户级通讯软件接口,提供了高性能的报文传输和RDMA通讯操作,MPICH2-CMEX是基于CMEX的MPI实现,结合RDMA读和RDMA写通讯操作的特性,MPICH2-CMEX实现了多种数据传输通道,并利用并行应用的近邻通讯模式,实现了混合通道数据传输方法,实际的应用测试表明,MPICH2-CMEX系统具有良好的性能和可扩展性。     

PVM应用移植到MPI问题的探讨

消息传递方式是广泛应用于一些并行机,特别是分布存储并行机的一种模式。ＰＶＭ（ＰａｒａｌｌｅｌＶｉｒｔｕａｌＭａｃｈｉｎｅ）和ＭＰＩ（ＭｅｓｓａｇｅＰａｓｓｉｎｇＩｎｔｅｒｆａｃｅ）都是目前是广受欢迎的基于消息传递的并行程序库,其中ＰＶＭ的消息传递接口,因其简单性,而没有给用户最大的灵活性以实现最佳的性能：为此,消息传递标准的讨论会工作组制定了消息传递接口ＭＰＩ标准,为ＰＶＭ实现最佳性能提供了可能。该文通过对ＰＶＭ和ＭＰＩ的比较,指出了从ＰＶＭ应用移植到ＭＰＩ应用时有利的方面和潜在的缺陷。如果一个应用程序能避开这些缺陷的影响,那么它就能够从移植中提高通信的性能,从而提高其分布式计算的性能。     

An implementation and evaluation of the MPI 3.0 one‐sided communication interface

The Message Passing Interface (MPI) 3.0 standard includes a significant revision to MPI's remote memory access (RMA) interface, which provides support for one‐sided communication. MPI‐3 RMA is expected to greatly enhance the usability and performance of MPI RMA. We present the first complete implementation of MPI‐3 RMA and document implementation techniques and performance optimization opportunities enabled by the new interface. Our implementation targets messaging‐based networks and is publicly available in the latest release of the MPICH MPI implementation. Using this implementation, we explore the performance impact of new MPI‐3 functionality and semantics. Results indicate that the MPI‐3 RMA interface provides significant advantages over the MPI‐2 interface by enabling increased communication concurrency through relaxed semantics in the interface and additional routines that provide new window types, synchronization modes, and atomic operations. Copyright © 2016 John Wiley & Sons, Ltd.     

The scalable process topology interface of MPI 2.2

The Message‐passing Interface (MPI) standard provides basic means for adaptations of the mapping of MPI process ranks to processing elements to better match the communication characteristics of applications to the capabilities of the underlying systems. The MPI process topology mechanism enables the MPI implementation to rerank processes by creating a new communicator that reflects user‐supplied information about the application communication pattern. With the newly released MPI 2.2 version of the MPI standard, the process topology mechanism has been enhanced with new interfaces for scalable and informative user‐specification of communication patterns. Applications with relatively static communication patterns are encouraged to take advantage of the mechanism whenever convenient by specifying their communication pattern to the MPI library. Reference implementations of the new mechanism can be expected to be readily available (and come at essentially no cost), but non‐trivial implementations pose challenging problems for the MPI implementer. This paper is first and foremost addressed to application programmers wanting to use the new process topology interfaces. It explains the use and the motivation for the enhanced interfaces and the advantages gained even with a straightforward implementation. For the MPI implementer, the paper summarizes the main issues in the efficient implementation of the interface and explains the optimization problems that need to be (approximately) solved by a good MPI library. Copyright © 2010 John Wiley & Sons, Ltd.     

Performance Modeling and Evaluation of MPI

Users of parallel machines need to have a good grasp for how different communication patterns and styles affect the performance of message-passing applications. LogGP is a simple performance model that reflects the most important parameters required to estimate the communication performance of parallel computers. The message passing interface (MPI) standard provides new opportunities for developing high performance parallel and distributed applications. In this paper, we use LogGP as a conceptual framework for evaluating the performance of MPI communications on three platforms: Cray-Research T3D, Convex Exemplar 1600SP, and a network of workstations (NOW). We develop a simple set of communication benchmarks to extract the LogGP parameters. Our objective in this is to compare the performance of MPI communication on several platforms and to identify a performance model suitable for MPI performance characterization. In particular, two problems are addressed: how LogGP quantifies MPI performance and what extra features are required for modeling MPI, and how MPI performance compare on the three computing platforms: Cray Research T3D, Convex Exemplar 1600SP, and workstations clusters.     

MPI网络通信模型的数值应用

讨论并行支撑环境MPI的并行通信性能模型，测试了点对点和组通信下的若干性能指标，归纳出这些性能指标的统计模型，以作为工程问题并行计算可行性和可扩充性评价的基础。     

消息传递界面PVM和MPI的现状与发展趋势

ＰＶＭ和ＭＰＩ是目前国际上最有影响的两种消息传递并行计算环境，两者都能在ＭＰＰ和工作站网络上运行。由于设计背景和侧重点不同，使得这两种界面既有共同点，又各具特色。文中就性能和发展趋势对两者进行叙述和比较，可供并行程序开发者选择并行计算环境时参考。     

三维Navier-Stokes方程分步法的并行算法在异构平台上实现初探

本文选取了三维不可压缩流动方程的分步法(fractional-step method),其中动量方程使用BiCGSTAB算法进行迭代求解,而压力泊松方程使用Fourier变换法进行直接求解。本文研究该算法在集群平台上的并行算法,从区域分解入手,分析一维、两维、三维区域划分三种情况下,各并行处理器上的计算量与通讯量,根据分析结果使用两维区域分解。分析BiCGSTAB算法和泊松Fourier变换法在GPGPU异构平台上的移植方法。最后,本文分析了BiCGSTAB和泊松方程Fourier变换法两种算法在CPU集群和GPGPU异构平台上的并行性能结果。     

Shared‐memory communication approaches for an MPI message‐passing library

This paper discusses several approaches to designing and implementing shared‐memory communication protocol modules for the message‐passing interface (MPI) libraries, colloquially called ‘shared‐memory devices’. The authors present a new taxonomy for classifying designs for shared‐memory MPI communication devices and formulate design evaluation criteria. Using these criteria, the authors compare three existing shared‐memory devices for MPICH and choose the best one. The authors also present experimental results that support their choice. The contributions of this paper are three‐fold. First, the authors present the taxonomy for shared‐memory communication devices. Second, they show advantages and potential problems of the devices that belong to different classes of their taxonomy using the formulated design criteria. Third, they analyze communication performance of existing MPICH shared‐memory devices, discuss optimizations of their performance, and show the performance gains that these optimizations yield. MPICH is used for comparison, since it is a widely used MPI implementation. Copyright © 2000 John Wiley & Sons, Ltd.