Repeater-based hybrid wired/wireless PROFIBUS network simulator

This technical report describes the Repeater-Based Hybrid Wired/Wireless PROFIBUS Network Simulator that implements a simulation model of the repeater-based approach. This approach defines the mechanism to extend the PROFIBUS protocol to supprot wireless communication, in which the interconnection of the wired and wireless segments is done by a intermediate system operating at Physical Layer, as repeater

Communication Infrastructures for Distributed Control of Power Distribution Networks

Accepted versio

Analysis of profibus communication using process automation and decentralised periphery against conventional (4-20MA)

The research Analyses, PROFIBUS Communication using Process Automation and Decentralized Periphery against Conventional (4-20mA) was based on the process plant constructed in 2012 by staff and students in the Department of Instrumentation and control at Mangosuthu University of Technology. Further work was not done including configuring the entire process plant, testing all devices and display the image of the process plant on human machine interface. The process plant operation was never tested and the research topic has not been attempted before. The research was conducted to improve the existing plant to full operation or functional project. The research study was conducted in March 2013 by BZT Ntshangase, it was established that both DP flowmeter and PA flowmeter were not tested before, not calibrated correctly and both drives which are (MM440 and MM420) were not setup to control both pump1 and pump 2 in manual or auto mode. The Programmable Logic Controller (PLC) was not configured to communicate with all devices on the network. PROFIBUS-DP and PROFIBUS-PA devices were not set up; input measurements were not scaled to read within certain limits. All devices used in the process plant were not assigned unique addresses for the network and DSG files were not installed so that Programmable logic controller (PLC) would identify all devices on the PROFIBUS network. The research was based on analysis of PROFIBUS communication using process automation and decentralized periphery against conventional (4-20mA), where one flowmeter was communicating with a PLC via PROFIBUS-DP and the other flowmeter was communicating through PLC via ET-200M to a DP/PA coupler. Research objective was to examine the time response between the two signals, data transmission, network configurations and their communication protocols and including transmission rate for both networks. Process plant components used in the research were tested for linear scaling, reliability, generalizability and validity. The reason for performing these tests was to produce consistent results and to checks how similar results are if the research was repeated under similar circumstances. During testing, respectable results were achieved. All simulated results were compared with the real-time results and then a conclusion drawn based on the obtained information and facts. Project design, implementation, test procedures and test results were achieved because prototype performed as per design and research objectives were achieved. Simulation tests were conducted and the obtained results analysed. The achieved results showed that the proposed solution or the prototype system performed as per design. The experimental results could be useful to other researchers in the future. At the end of the study conclusion and some recommendations for further studies are discussed efficiently to utilize resources in the process plant verification and validation.Electrical EngineeringM. Tech. (Electrical Engineering

A Dual-Rate Model Predictive Controller for Fieldbus Based Distributed Control Systems

In modern Distributed Control Systems (DCS), an industrial computer network protocol known as fieldbus is used in chemical, petro-chemical and other process industries for real-time communication between digital controllers, sensors, actuators and other smart devices. In a closed-loop digital control system, data is transferred from sensor to controller and controller to actuator cyclically in a timely but discontinuous fashion at a specific rate known as sampling-rate or macrocycle through fieldbus. According to the current trend of fieldbus technology, in most industrial control systems, the sampling-rate or macrocycle is fixed at the time of system configuration. This fixed sampling-rate makes it impossible to use a multi-rate controller that can automatically switch between multiple sampling-rates at run time to gain some advantages, such as network bandwidth conservation, energy conservation and reduction of mechanical wear in actuators. This thesis is concerned about design and implementation of a dual-rate controller which automatically switches between the two sampling-rates depending on system’s dynamic state. To be more precise, the controller uses faster sampling-rate when the process goes through transient states and slower sampling-rate when the process is at steady-state operation. The controller is based on a Model Predictive Control (MPC) algorithm and a Kalman filter based observer. This thesis starts with theoretical development of the dual-rate controller design. Subsequently, the developed controller is implemented on a Siemens PCS 7 system for controlling a physical process. The investigation has concluded that this control strategy can indeed lead to conservation of network bandwidth, energy savings in field devices and reduction of wear in mechanical actuators in fieldbus based distributed control systems

A study on industrial communication networking: ethernet based implementation

Recent enhancement of an industrial communication and networking technology has made it possible to apply Ethernet networks at all levels of industrial automation, especially at controller level where the data exchange in real-time communication is mandatory. This thesis presents a study on the development of industrial communication network based on the Ethernet and its implementation on a Computer Integrated Manufacturing (CIM-70A) system which located at Robotic Laboratory in KUiTTHO. The Ethernet module was installed on supervisory OMRON PLC to integrate the various stations in the ClM-70A system. The workability of this communication technique was analyzed and compared with the conventional serial communication which is widely used in automation networking systems. Through this approach, the communication and integration of elM systems can be accessed easily and hence available to be upgraded to the management and enterprise levels of automation

A multiple logical ring approach to real-time wireless-enabled PROFIBUS networks

Tese de Doutoramento. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 200

A Safety Layer for Foundation Fieldbus

The focus of the work of this Cand. scient. thesis has been placed upon understanding and developing a concept for using digital communication in safety-critical applications. It is increasingly common to use programmable technology in a safety-critical control system. These new software-based components are in many cases replacing existing hard-wired and analogue components that have safety-critical functions. Implementing these software-based safety-critical systems require more in-depth methods and concepts than what traditionally has been used in software engineering. I have concentrated my studies around problems concerned with using fieldbus technology between the subsystems in a software-based safety-critical system. During the work on this thesis I have had to acquire a substantial amount of knowledge about subjects not previously covered in my studies. I have gained knowledge about industrial process control systems, safety-critical systems, international IEC standards for safety systems, various fieldbus technologies, coding theory and hardware related programming. The basic knowledge required to appreciate the contents of this thesis is presented as background information in the introductory chapters. One of the main goals of this thesis has been to analyse and find out if it is possible to implement a safe communications protocol for Foundation Fieldbus fulfilling the stringent requirements of a SIL 3 application. My studies are based on a concept of a general communication protocol called a "Safety Layer." A safety layer defines methods for increasing the probability of detecting errors that may occur between two communicating fieldbus devices. The safety layer’s objective is to make the transmission "safer" between two nodes in a fieldbus network. This involves enabling the communication parties to determine that messages have the right value, they are sent in the correct sequence and to the right time and have correct origin/destination. In my thesis I have further developed the basic idea behind the safety layer in a general sense so that it can in principle be used on top of any communication protocol to provide safe communication. This study has furthermore been extended with an implementation of a safety layer prototype for Foundation Fieldbus. The purpose of this implementation is to demonstrate how Foundation Fieldbus can be made safer and that the concept and ideas of the general safety layer are feasible. The protocol incorporates a method for enabling two-way communication between two function blocks and new CRCs for improved error detection. The choice of generator polynomials for these CRCs has been based on probabilistic considerations. The safety layer also specifies a communication mode that sanctions transmissions of amounts of data larger that the maximum allowed transmission unit. The implementation of the safety layer is unique in its kind. Similar work has never before been done for Foundation Fieldbus. I do not assume any liability for any accidents, loss or damage caused as a result of any errors or omission in this thesis

An application of an ethernet based protocol for communication and control in automated manufacturing

The exchange of information in the industrial environment is essential in order to achieve complete integration and control of manufacturing processes. At present the majority of devices present in the shop floor environment are still used as stand alone machines. They do not take advantage of the possibilities offered by a communication link to improve the manufacturing process. The subject of this research has been centered on the development of a simple, flexible and inexpensive support system for communication and control of manufacturing processes. As a result, a system with these features has been proposed and implemented on a simulated workcell. The area footwear manufacturing was chosen for modelling the workcell. The components of the manufacturing support system were developed using an object oriented approach which allowed modularity and software reuse. In order to achieve communication between the components, a communication protocol was developed following the process defined in the rapid protocol implementation framework. Ethernet was selected for implementing the lower levels of the protocol. Java, a new object oriented programming language used for the implementation of the system, showed that it could became a promising language for the implementation of manufacturing applications. In particular the platform independence feature of the language allows the immediate porting of applications to systems with different features. The manufacturing cell simulation had shown that the times associated with the manufacturing support system operations are compatible for its use in applications where the response times are in the order of one second

Avaliação do desempenho de redes PROFIBUS-DP suportada em técnicas de injecção de faltas

Tese de doutoramento. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 200