基于Modbus TCP协议的计算机与PLC的通信

简要介绍了Modbus TCP协议。研究了基于Modbus TCP协议实现上位机和PLC通信的方法。PLC选用台达DVP-12SE型机,上位机采用Visual C++6.0编程,向PLC发送Modbus TCP命令,与PLC进行信息交换。给出端口初始化、发送数据和接收数据等各部分程序代码。该方法为进一步开发PLC监控系统提供了有价值的参考。

Modbus TCP协议安全风险分析及对策研究

工业互联网作为新一代信息技术与工业系统深度融合的产物,正推动着工业生产方式的变革。然而,工控网络协议在设计之初因注重效率提升和功能实现忽视了一些安全性问题,加之应用中的安全漏洞和异常行为,导致其存在严峻的安全隐患。文章介绍了工业互联网的发展背景、趋势和工控网络协议特点,分析了当前应用最广泛的典型工控网络协议Modbus TCP的安全风险,研究了数据加密、数据完整性检测、身份认证及异常入侵检测等安全对策,提出一套Modbus TCP协议安全方案。该方案包含采用AES算法和RSA算法的数据加密和解密模块、采用SM3算法的数据完整性检测模块、采用动态口令认证技术的身份认证模块和基于数据特征的异常入侵检测系统,同时引入PKI进一步加强工控系统的安全性,为其他工控网络协议的安全防范提供借鉴和参考。

基于TCP通信协议与区块链的财务信息数据共享方法

为了优化财务信息数据共享效果,提高数据共享传输的安全性与完整性,本文开展了基于TCP通信协议与区块链的财务信息数据共享方法研究。首先,采用预查询技术,检索财务信息数据,找出共享所需要的数据;其次,利用区块链技术,对检索到的财务信息数据进行加密处理,保证数据的安全性;在此基础上,利用TCP通信协议,设计数据共享传输机制,实现财务信息数据安全共享。实验结果表明,提出的方法应用后,数据共享误码率较低,说明该方法共享的财务信息数据更加准确,数据的可信度、安全性与完整性较高。

TCP协议以及多路径传输协议研究进展

文章主要研究了TCP传输协议以及MPTCP多路径网络传输的研究进展。首先,文章对TCP的传输原理以及各项问题和应用进行研究,引用若干典型案例阐述TCP传输协议的优势及其存在的局限性,给出相应建议和改进措施;其次,提出了MPTCP多路径网络传输是当下一种提高网络速度可行、高效的方式,但MPTCP在公平性、安全性、网络速度等方面还存在问题,故未达到可以全面普及的程度;最后,详细介绍了MPTCP多路径网络传输协议的发展趋势与难题,提出采用做多路径传输的代理的方式可以优化传输性能。

基于电力云边协同的非侵入式Modbus TCP协议安全增强方法

分布式电源(distributed resources,DR)中智能边缘设备数据传输的安全问题为电力系统带来了安全隐患。Modbus TCP(transmission control protocol)协议作为边缘设备采用的通信手段之一,其协议安全性的不足使得系统易遭到网络空间的攻击。为保障电力设备数据传输安全,对现有安全手段进行整理,分析现有安全手段在DR应用场景下的不足,提出一种非侵入式Modbus TCP协议安全增强方法。该方法采用云边协同的架构,利用电力控制中心云平台管理访问控制原则,将实际访问控制决策模块部署在边缘设备,并通过细粒度的访问控制组合限制恶意行为。依据Modbus协议参考指南,搭建DR应用场景进行渗透测试,验证该方法能有效防御重放攻击和中间人攻击,可将安全开销控制在百微秒以内,显著优于其他安全手段,满足DR对实时性的需求。

改进TCP/IP帧结构的多参数信道传输性能评估方法

目前,网络密集化现象加剧了信道传输性能的恶化。而普遍应用的评估方法由于参数考虑有限和适用范围受限,在信道传输性能评估方面面临显著挑战。针对信道传输性能评估困难的问题,提出一种改进传输控制协议/网际协议(TCP/IP)帧结构的多参数信道传输性能评估方法。首先,生成标准化的测试数据,包括伪随机码、基本曲线数据、自定义曲线数据,以确保测试数据遵循统一标准;其次,使用改进的TCP/IP帧结构,将总帧数、帧序号等测试数据信息封装在TCP/IP帧中,并对测试数据进行收发与解析,统计不同帧类型的帧数量、不同帧长度的帧数量、总帧数和有效数据量这4种基础信道传输信息;最后,分析接收数据得到误帧率和误码率这2种高级信道传输信息,完成信道传输性能的整体评估。所设计的方法采用6种不同的参数对信道质量进行评估,方法评估的精度可达0.01%,最小误差为0.01%,且兼容所有使用TCP/IP进行通信的信道。实验结果表明,所提出的信道传输性能评估方法可以完成对6种信道通信信息的统计与分析,准确评估信道传输性能。

基于Modbus/TCP协议的ATS与FSK系统间通信接口设计

根据墨西哥某城市地铁指挥控制系统的设计需求,列车自动监控(ATS)系统与频移键控(FSK)系统之间数据交互采用网络接口,基于Modbus/TCP协议实现相应的以太网通信。为此提出基于Modbus/TCP协议的ATS与FSK系统间通信接口设计方案:利用Modbus/TCP协议的扩展灵活性,在传统Modbus/TCP协议的基础上进行扩展,实现ATS与FSK系统间的模拟列控信息、列车检测信息、FSK传输配置信息、网络配置信息的安全可靠传输;为了高效便捷地将从网口接收的信息解析后传输给FSK系统,选择在ARM/Linux+FPGA平台上实现通信接口。测试验证结果表明:该通信接口设计方案结构清晰且方便移植,能够正确有效地实现ATS与FSK系统间通信。

AN ENHANCEMENT SCHEME OF TCP PROTOCOL IN MOBILE AD HOC NETWORKS:MME-TCP

Transmission Control Protocol (TCP) optimization in Mobile Ad hoc NETworks (MANETs) is a challenging issue because of some unique characteristics of MANETs. In this paper,a new end-to-end mechanism based on multiple metrics measurement is proposed to improve TCP performance in MANETs. Multi-metric Measurement based Enhancement of TCP (MME-TCP) designs the metrics and the identification algorithm according to the characteristics of MANETs and the experiment results. Furthermore,these metrics are measured at the sender node to reduce the overhead of control information over networks. Simulation results show that MME-TCP mechanism achieves a significant performance improvement over standard TCP in MANETs.

基于TCP/IP协议实现西门子PLC与上位机的通信

介绍基于TCP/IP协议在西门子PLC与上位机之间实现通信,结果表明在西门子PLC与上位机间使用TCP通信方式简便、可靠,对其他工具软件依赖性小,在工业应用领域中有较高的实用价值。

无线网络中TCP/NC协议性能分析与仿真验证

为改进传统传输控制协议(TCP)在无线网络中的性能,运用Matlab对TCP Reno,TCP Vegas和基于网络编码的TCP/NC吞吐率分析模型进行数值求解,分析3个模型在不同网络环境下应达到的理论值,验证TCP/NC模型在理论上能否提高其吞吐率。基于NS-2对3种吞吐率模型进行仿真,结果表明,TCP/NC及其分析模型可有效改进TCP协议。

基于LwIP和Modbus TCP协议的网络控制器设计

为了实现对终端设备的网络远程控制和监测,该文设计了一款基于LwIP和Modbus TCP协议的网络控制器。该控制器以STM32F107RCT6和LAN9303芯片为核心,设计出了网络通信电路、网口电路、A/D采样电路、光耦隔离电路和IO口电路。软件设计主要完成了LwIP协议栈的移植、Modbus TCP协议程序和其他控制程序的编写。经过测试,所设计的网络控制器在对设备进行远程控制和监测时具有数据传输可靠、通讯稳定和实时性好的优点,能满足工厂使用。

Modbus TCP/IP协议仿真应用设计

针对Modbus TCP/IP协议通信的特性,研究并设计出一种Modbus TCP/IP协议仿真应用方案。利用MFC框架,分别对协议中客户端和服务器端的功能进行设计,完成对客户端和服务器端的仿真实现,最后用仿真应用对Modbus TCP/IP协议模拟展示。展示结果表明,此仿真应用设计可以完整模拟出Modbus TCP/IP协议的通信流程,这可以更方便地对Modbus TCP/IP协议的通信过程进行模拟和理解,有效支持工控网络安全课程的协议建模与分析实验。

TCP-Rab： a receiver advertisement based TCP protocol

With the evolution of network technologies, the deficiencies of TCP protocol are becoming more and more distinct. The new TCP implementation, called Receiver Advertisement Based TCP (TCP-Rab) proposed here to eliminate these deficiencies, adopts two basic mechanisms: (1) Bandwidth Estimation and (2) Immediate Recovery. Bandwidth estimation is carried out at the receiver, and the result is sent back to the sender via the acknowledgments. Immediate Recovery guarantees high performance even in lossy link. Rab can distinguish the reason for packet loss, and thus adopt appropriate recovery strategy. For loss by network congestion, it will back off its congestion window, and for loss by link errors, it will recover the congestion window immediately. Simulations indicated that Rab has superiority over other TCP implementations.

基于LSTM的Modbus TCP协议模糊测试优化方法

针对工控系统传输协议模糊测试的路径爆炸和约束求解问题,提出一种基于长短时记忆(LSTM)网络的Modbus TCP协议模糊测试优化方法,挖掘出两种工控协议漏洞,分别为非法写入漏洞和数据值边界漏洞。抓取模糊测试数据包形成数据集,并根据状态码将其分为正常用例、异常用例和无效用例三种,通过LSTM识别出无效用例并剔除,提高漏洞挖掘效率。实验结果表明,LSTM识别模糊测试数据集的准确率达到93.87%,经过LSTM优化后的测试用例通过率从30.75%提升至33.99%。

A New Approach for Performance Evaluation of TCP over Interference-Limited Wireless Channels over Interference Wireless Channels

A new metric for performance evaluation of transport control protocol(TCP) overwireless channels based on the interference-limited characteristics of code division multipleaddress(CDMA) system is proposed.According to the new metric,the performance of TCP over CDMAcorrelated channel for different protocol parameters and different versions is investigated.The resultsshow that appropriate selection of protocol parameters and packet error rate(PER) operation point canimprove significantly the capacity of packet-switched CDMA-based network.

Modbus TCP通信协议在PLC课程中的应用

传统PLC课程采用的通信协议主要是西门子S7协议、三菱CC-LINK协议,只能用于同种PLC之间的通信。而Modbus TCP通信协议可匹配多种不同类型的工业控制设备,能够极其方便地在不同类型设备间建立可靠稳定快速的通信。因此,本文介绍了Modbus TCP通信协议在PLC课程中的应用。

Modeling TCP Incast Issue in Data Center Networks and an Adaptive Application-Layer Solution

In data centers, the transmission control protocol(TCP) incast causes catastrophic goodput degradation to applications with a many-to-one traffic pattern. In this paper, we intend to tame incast at the receiver-side application. Towards this goal, we first develop an analytical model that formulates the incast probability as a function of connection variables and network environment settings. We combine the model with the optimization theory and derive some insights into minimizing the incast probability through tuning connection variables related to applications. Then,enlightened by the analytical results, we propose an adaptive application-layer solution to the TCP incast.The solution equally allocates advertised windows to concurrent connections, and dynamically adapts the number of concurrent connections to the varying conditions. Simulation results show that our solution consistently eludes incast and achieves high goodput in various scenarios including the ones with multiple bottleneck links and background TCP traffic.

Experimental study of channel delay impact on throughput performance of TCP and its extensions in space

Substantially long round trip time (RTT) in space channel hurts TCP interactions between the sending and receiving ends, and limits the usefulness and effectiveness of TCP feedback. Space Communication Protocol Standards-Transport Protocol (SCPS-TP) is a Transmission Control Protocol (TCP) enhancement method aimed at improving its performance in space and interplanetary Internet and is expected to have capability of being feasible applied to experimental evaluation of the effectiveness of SCPS-TP in coping with long channel delay. This paper presents an experimental evaluation of channel delay impact on throughput performance of SCPS-TP over LEO/GEO-stationary space links using a test-bed, compared with the widely deployed TCP.

TCP TRAFFIC PERFORMANCE IMPROVING IN LTE-A NETWORKS

This paper presents a novel way to improve Transmission Control Protocol (TCP) performance of the users at the edge areas of the macro cells in Long Term Evolution Advanced (LTE-A) systems. Previous works on improving wireless TCP performance are reviewed and current considerations on TCP in LTE-A are explained. However, those solutions are neither too complex nor limited to some presuppositions which are too restricting for the deployment of LTE-A networks. In this paper a substituted TCP acknowledgement transmission scheme based on Automatic Repeat reQuest (ARQ) information in layer 2 is proposed. The simulation result shows that the proposed method can reduce the delay and improve the throughput of the edging users of the cell, as well as reducing radio resources in LTE-A macro cells.

The Design and Implement of TCP/IP Protocol Cluster on AVR Singlechip

With the rapid development of the embedded technology, research and implement of the Internet of things will be a new technology revolution, yet the implement of the Internet of things is on the base of the communication between the things. For this reason, realizing the function of communication between singlechip is particularly important. Based on the characteristics of the embedded microcontroller, we analyzed the traditional PC TCP/IP protocol, and appropriately tailored TCP/IP protocol cluster on the basis of the characteristics of embedded singlechip. At last, we realized the reduced TCP/IP protocol cluster suitable for embedded singlechip, on AVR singlechip platform.