GPRS远程监控的现场总线控制系统

为了便于超级用户远程监控生产过程,设计手机用户与现场总线控制系统通信方案,即采用网间协议转换器硬集成方法,解决不同协议的现场总线设备与上位控制系统之间的通信问题。在实现Modbus与Profibus-DP、GPRS网络之间的数据透明传输的基础上,完成了S7-400 PLC与Modbus PLC设备之间的数据采集和监视控制,达到了异构现场总线协议设备集成的目的。利用GPRS网络,搭载移动通信网络,构建了一个无线、异地、全天候的现场总线控制系统远程监控系统。     

基于通讯协议网关转换的LFT造粒自动化系统设计

阐述了LFT造粒生产线自动化系统的设计思路,针对其中通讯兼容性的问题,提出了一种利用网关实现Profibus-DP/Modbus通讯协议转换的方案,通讯协议网关作为中转站将经Modbus协议采集的现场设备模拟量和数字量进行转换,再经Profibus协议传输到PLC中。并结合Profibus-DP/Modbus协议的主要参数和通讯特点,详细介绍了串口网关的软硬件配置方法、各仪表的参数设置以及西门子STEP7的配置方法,实现了西门子S7-300型PLC、施耐德PLC以及欧姆龙控温仪表的异构连接和通讯。采用西门子组态软件STEP7 V5.5和Win CC,开发了连续长纤浸渍包覆造粒生产线控制系统。在大幅降低成本的基础上,减少了人工操作,提高了生产效率和自动化程度。     

智能温控表与工业以太网的通讯

温度仪表是众多仪表中的一个分支,常见的温度仪表有温度计,温度记录仪,温度送变器等。本文讲述的是ERO温控表通过Prosoft 485模块与Control Logix控制系统的Modbus通讯,并经由Control Logix控制系统的以太网模块得以实现与工业以太网的通讯。     

基于ASCII协议的CP341与约克冷冻机的通讯

工厂自动化领域经常遇到通过串口通讯,把分散独立的成套设备的控制单元集成到一个总控制系统下,以便集中监视独立成套设备的运行状况。本例介绍了昆腾约克冷冻机与西门子DCS的串口通讯的实现过程。对使用ASCII协议的DCS如何发送给使用WODBUSASCII通讯协议的冷冻机串口通讯命令,以及DCS接收到冷冻机通讯数据后如何翻译成现场仪表的运行参数的实现过程作了详细重点的介绍．     

JX-300XP和S7-300PLC的数据通讯

运用Modbus通讯协议实现JX-300XP系统和S7-300PLC之间的通讯,给出了通讯建立的程序代码及数据类型转换代码。在系统实际运行中,该方法建立的数据通讯正常运行,可推广运用到JX-300XP与其它装置的Modbus通讯。     

JX-300XP和S7-300PLC的数据通讯

运用Modbus通讯协议实现JX-300XP系统和S7-300PLC之间的通讯,给出了通讯建立的程序代码及数据类型转换代码.在系统实际运行中,该方法建立的数据通讯正常运行,可推广运用到JX-300XP与其它装置的Modbus通讯.     

基于Profibus-DP/Modbus网关的双阶挤出机组温度控制系统设计

介绍了应用于双阶挤出机组的集中温度控制系统的设计,详细阐述了通过Profibus-DP/Modbus网关实现可编程逻辑控制器S7-300与温度控制仪表之间的通讯。实现双阶挤出机组各处温度的集中控制,以便生产工艺的统一管理和历史数据的记录与归档。研究结果表明,这种通讯方式具有响应速度快、软件设计简单以及成本低等优点。     

基于西门子CP341的温控仪表通讯实现

为了实现西门子PLC与智能仪表通讯,本例采用SIMATIC S7系列串行通讯处理器CP341与理化RKC402仪表进行ASCⅡ协议通讯,使用S7软件编写串口ASCⅡ码通讯报文程序,既解决了Modbus RTU主从通讯需要单独Modbus Dongle的不便,又使西门子PLC串口通讯具有更强的普遍性和灵活性。     

通信技术在离心机控制系统中的应用

介绍了在离心机控制系统中的一项技术,它利用变频器的RS485串行通讯接口和PLC进行Modbus协议通讯,从而实现了PLC与变频器的串行通信控制,达到监控离心机系统设备多组参数的同时还能降低系统成本的目的。     

基于工业以太网与Modbus的多台西门子PLC与DCS的通信系统

根据某化工厂多台加热炉项目控制系统的特点和要求,设计了多台加热炉S7-300 PLC与DCS之间的工业以太网通信系统,通过TCP/IP协议实现各PLC所需与DCS通信数据的汇总,只用一个Modbus RTU接口与DCS互连,完成多台PLC与DCS之间的数据通信,并介绍了相应的硬件设计和软件编程。实际应用表明:由工业以太网和Modbus构成的通信系统具有成本相对低廉以及可靠性高等特点。     

控制集成技术在油气初加工装置应用

现分公司部分装置站内存在若干分散的控制系统,彼此独立互不通信,形成了信息孤岛,未达到分散控制集中监控的目的。本项目重点解决了站内各监控点中不同类型PLC与主控中心ME控制系统的通信问题,以实现在主控中心对站内所有的生产数据进行集中监控。并将分散的控制系统集成到统一的控制系统平台上,实现了监控过程可视化、一体化的同时,可扩大信息共享,提高信息利用率,实现管控一体化。在降低企业的运行成本,提高分公司生产运行效率的同时,全面提升分公司生产装置的自动化控制水平和管理水平。     

A Multi-layer Information Integration Platform for Chemical Process Operation Systems

In the process industry, automation and process control systems are widely implemented, information integration is however far away from satisfactory. It remains a hard job for senior managers to make decisions based on the plant-wide real-time integrated information. This paper proposes a multi-layer information integration platform. In the data integration level, the standard for the exchange of product (STEP) and the extensible markup language (XML) are used to unify these data of the chemical process. In the model integration level, the models are integrated by using the neutral model repository and CAPE-OPEN. In the integration of process task, the common object request broker architecture (CORBA) is used as the communication mediator. The XML is taken as the data standard. A uniform information platform is thus constructed and realized. The proposed information integration platform is satisfactorily implemented to solve the Tennessee Eastman (TE) problem.     

一个化工过程运行系统的多层信息集成平台

In the process industry, automation and process control systems are widely implemented, information integration is however far away from satisfactory. It remains a hard job for senior managers to make decisions based on the plant-wide real-time integrated information. This paper proposes a multi-layer information integration platform. In the data integration level, the standard for the exchange of product (STEP) and the extensible markup language (XML) are used to unify these data of the chemical process. In the model integration level, the models are integrated by using the neutral model repository and CAPE-OPEN. In the integration of process task, the common object request broker architecture (CORBA) is used as the communication mediator. The XML is taken as the data standard. A uniform information platform is thus constructed and realized. The proposed information integration platform is satisfactorily implemented to solve the Tennessee Eastman (TE) problem.     

A two-tier architecture for networked process control

Traditionally, process control systems utilize dedicated, point-to-point wired communication links using a small number of sensors and actuators to regulate appropriate process variables at desired values. While this paradigm to process control has been successful, chemical plant operation could substantially benefit from an efficient integration of the existing, point-to-point control networks (wired connections from each actuator/sensor to the control system using dedicated local area networks) with additional networked (wired or wireless) actuator/sensor devices. However, augmenting existing control networks with real-time wired/wireless sensor and actuator networks challenges many of the assumptions made in the development of traditional process control methods dealing with dynamical systems linked through ideal channels with flawless, continuous communication. In the context of control systems which utilize networked sensors and actuators, key issues that need to be carefully handled at the control system design level include data losses due to field interference and time delays due to network traffic. Motivated by the above technological advances and the lack of methods to design control systems that utilize hybrid communication networks, in the present work, we present a novel two-tier control architecture for networked process control problems that involve nonlinear processes and heterogeneous measurements consisting of continuous measurements and asynchronous, delayed measurements. This class of control problems arises naturally when nonlinear processes are controlled via control systems based on hybrid communication networks (i.e., point-to-point wired links integrated with networked wired/wireless communication) or utilizing multiple heterogeneous measurements (e.g., temperature measurements which can be taken to be continuous and species concentration measurements which are fed to the control system at asynchronous time instants and frequently involve delays). While point-to-point wired links are very reliable, the presence of a shared communication network in the closed-loop system introduces additional delays and data losses and these issues should be handled at the controller design level. In the two-tier control architecture presented in this work, a lower-tier control system, which relies on point-to-point communication and continuous measurements, is first designed to stabilize the closed-loop system, and an upper-tier networked control system is subsequently designed, using Lyapunov-based model predictive control theory, to profit from both the continuous and the asynchronous, delayed measurements as well as from additional networked control actuators to improve the closed-loop system performance. The proposed two-tier control architecture preserves the stability properties of the lower-tier controller while improving the closed-loop performance. The applicability and effectiveness of the proposed control method is demonstrated using two chemical process examples.     

Integration of scheduling and control—Theory or practice?

Today's industries are more than ever forced to lower their operational costs, especially during the ongoing economic recession where the whole existence of many businesses is endangered. This has created a need of increased information sharing between various decision-support systems. The target is to have full transparency and ensure that the overall result of individual optimization tasks is “globally optimal”, i.e., that the decisions taken on different levels do not negate each other. This leads inevitably to more complex optimization systems as the models tend to cover larger problem entities in order to merge previously separated optimization targets or include earlier not considered aspects in order to avoid getting stuck into unfavorable local optima. Another complexity arises from the need of communication between the tasks—earlier isolated problems become networked, which means that the definition of optimization goals cannot be derived from local facts alone. This paper discusses some issues emerging from the integration of production scheduling and control. Some existing standards to support the integration challenge are presented, followed by an overview of recent research results. An interesting question is to what extent such an integration activity is the task of a scientist or a practitioner? The paper concludes by highlighting important open questions and raises some remaining challenges for the future.     

城市供水多系统集成SCADA调度信息平台

城市供水调度平台总体构架已经从过去的单一系统普遍进入到多系统集成的形式,以上海闵行自来水公司作为例,论述了调度中心平台采用调度主PLC兼容不同类型自控系统以及不同形式通信网络的方法和解决方案,从而实现了多系统接入的开放性综合调度平台的目标。     

Heat Integration for Different Separation Processes

The distribution of heat duties among individual separation subsystems and other as-pects of heat intergration in such systems are reviewed. Heat integration for different separation processes is investigated, using the pinch point method, Such a study will provide theoretical guide lines for the proper choice of a desirable separation process.     

A NONLINEAR EXPLICIT ALGORITHM FOR EFFICIENT INTEGRATION OF STIFF SYSTEMS OF ORDINARY DIFFERENTIAL EQUATIONS

An efficient algorithm for the integration of stiff systems of ordinary differential equations based on the boundary value technique is derived. The automatic step-size control procedure can be easily adapted. Results for a very stiff problem are compared with those obtained by other methods and the high effectiveness of the method is shown.     

A NONLINEAR EXPLICIT ALGORITHM FOR EFFICIENT INTEGRATION OF STIFF SYSTEMS OF ORDINARY DIFFERENTIAL EQUATIONS

An efficient algorithm for the integration of stiff systems of ordinary differential equations based on the boundary value technique is derived. The automatic step-size control procedure can be easily adapted. Results for a very stiff problem are compared with those obtained by other methods and the high effectiveness of the method is shown.     

Integration of scheduling and control with online closed-loop implementation: Fast computational strategy and large-scale global optimization algorithm

In this paper, we propose a novel integration method to solve the scheduling problem and the control problem simultaneously. The integrated problem is formulated as a mixed-integer dynamic optimization (MIDO) problem which contains discrete variables in the scheduling problem and constraints of differential equations from the control problem. Because online implementation is crucial to deal with uncertainties and disturbances in operation and control of the production system, we develop a fast computational strategy to solve the integration problem efficiently and allow its online applications. In the proposed integration framework, we first generate a set of controller candidates offline for each possible transition, and then reformulate the integration problem as a simultaneous scheduling and controller selection problem. This is a mixed-integer nonlinear fractional programming problem with a non-convex nonlinear objective function and linear constraints. To solve the resulting large-scale problem within sufficiently short computational time for online implementation, we propose a global optimization method based on the model properties and the Dinkelbach's algorithm. The advantage of the proposed method is demonstrated through four case studies on an MMA polymer manufacturing process. The results show that the proposed integration framework achieves a lower cost rate than the conventional sequential method, because the proposed framework provides a better tradeoff between the conflicting factors in scheduling and control problems. Compared with the simultaneous approach based on the full discretization and reformulation of the MIDO problem, the proposed integration framework is computationally much more efficient, especially for large-scale cases. The proposed method addresses the challenges in the online implementation of the integrated scheduling and control decisions by globally optimizing the integrated problem in an efficient way. The results also show that the online solution is crucial to deal with the various uncertainties and disturbances in the production system.