Foundation Fieldbus Research Articles

Educational Foundation Fieldbus Pilot Plant

The paper presents a pilot plant built to demonstrate the principles of process control using the FoundationFieldbus (FF) technology. Some theoretical background is given by explaining the logical layers of the technology,namely the physical layer, the communication stack and the user layer. Practical aspects, like the configuration ofinstruments, the design of a control strategy and the development of supervision software, are also covered by means of an application example. The example runs on the pilot plant making use of pressure, level and flow control loops,quantities widely found in the process industry. Experimental results are extracted and analyzed in order to evaluatethe overall performance of the system.

Centralized and distributed control architectures under Foundation Fieldbus network

This paper aims at discussing possible automation and control system architectures based on fieldbus networks in which the controllers can be implemented either in a centralized or in a distributed form. An experimental setup is used to demonstrate some of the addressed issues. The control and automation architecture is composed of a supervisory system, a programmable logic controller and various other devices connected to a Foundation Fieldbus H1 network. The procedures used in the network configuration, in the process modelling and in the design and implementation of controllers are described. The specificities of each one of the considered logical organizations are also discussed. Finally, experimental results are analysed using an algorithm for the assessment of control loops to compare the performances between the centralized and the distributed implementations.

A novel real-time fuzzy adaptive auto-tuning scheme for cascade PID controllers

This paper presents a novel fuzzy auto-tuning methodology to continuously adapt PID control actions without interrupting the normal process operation. New auto-tuning rules are introduced to schedule a gradual and guided activation of each individual P, I and D control mode in three adjustable functional control zones. An auto-scaling procedure has been incorporated to generalize the autotuning scheme to efficiently respond to any set-point change outside a pre-defined operating span. In contrast to existing auto-tuning algorithms, the proposed scheme is not an on-demand auto-tuning methodology and hence does not require alertness of an experienced engineer to initiate and supervise its initial operation in a separate commissioning identification pre-test. This interesting feature provides a new perspective on PID auto-tuning approaches. Performance of the proposed auto-tuning scheme is practically evaluated in a real pilot plant within a networked control system (NCS) configuration, realized by industrial Ethernet and Foundation Fieldbus technologies. An extensive series of test scenarios has been conducted to explore efficiency of the proposed auto-tuning methodology to cope with fixed and varying operating set-points under uncertain and variable network transmission time delays and external disturbance.

Evaluation of Foundation Fieldbus H1 Networks for Steam Generator Level Control

The effects of Foundation Fieldbus (FF) H1 networks on the dynamic performance of steam generator level control (SGLC) loops are evaluated through two experimental setups using a DeltaV Distributed Control System (DCS). The first uses a physical system resembling a steam generator; the second is a hardware-in-the-loop (HIL) simulation with a steam generator model inside an industrial-grade nuclear power plant training simulator. The test results indicate that for a given control loop a longer FF H1 macrocycle will lead to more serious performance degradation. Furthermore, the effects of the networks are found to be mainly due to network-induced delays. Through the timing analysis of an FF-H1-network-based loop, delay models are developed, and suggestions to potentially reduce the delays and their impact are provided.

Evaluation of Delays Induced by Profibus PA Networks

The delays associated with the use of Profibus process automation (PA) networks within control loops are investigated in this paper. A SMAR IF303 device, a SMAR FI303 device, a DeltaV distributed control system, and a Siemens DP/PA link are used to implement a Profibus-PAnetwork-based test loop. Both analysis and experiments are performed on the test loop. Loop-back delay models are developed and then validated against experimental results. Suggestions to potentially reduce Profibus-PA-network-induced delays are provided. A comparison between the estimated and the measured loop-back time demonstrates the accuracy of the delay models. Furthermore, the Profibus-PA-network-induced delays are compared against the delays induced by an equivalent Foundation Fieldbus H1 network with either hybrid or control-in-the-field architecture.

Extension of prioritized data analysis in the Foundation Fieldbus to three classes

AbstractThe Foundation Fieldbus data link layer provides both a token‐passing service required for sporadic data and a scheduled service for periodic data. It has three priority levels: urgent, normal, and time‐available. Modeling the virtual token rotation time (VTRT), which is the time required to receive tokens for the transmission of one's own data, is difficult due to the interactive data delay driven by the three priority levels. Therefore, a simplified mathematical model consisting of just two priority levels has been considered. In a previous research, the VTRT probability density function was defined using the probability of a token generation; however in the present study, a simpler expression was successfully developed in a system of three priority levels by tracking the token's priority changes generated by the link active scheduler. These priority changes are tracked by using the state transition probability and the state transition diagram of a token. Therefore, the success of this new mathematical model makes this research important. Furthermore, we found the existence and the cause of a fluctuating state, both of which are useful to a system designer for setting network parameters. The validity of the analytical model was verified in a simulation experiment. Copyright © 2011 John Wiley & Sons, Ltd.

A bandwidth allocation scheme in fieldbuses

Field devices in factory automation and process control systems generate time-critical, periodic, and time-available data. These data share the bandwidth of one fieldbus network medium. This paper reviews a bandwidth allocation scheme (BAS) that is applicable to many different kinds of field-buses. The BAS satisfies the real-time transmission requirements of time-critical and periodic data, and fully utilizes the bandwidth resources of the fieldbus network. The basic concept of the BAS is introduced and its implementation in Foundation Fieldbus, Profibus, and CAN protocols is discussed.

Optimized combustion system in coal-fired boiler: using optimization control and fieldbus

This paper presented a comprehensive design and implementation of control and optimization for the combustion system in heat-supplying boilers based on a fieldbus, mainly including the air-to-fuel ratio optimization algorithm based on a PID controller and soft measurement methodology for airflow based on the orifice nature of the air pre-heater. After process description and general control schemes were presented, measurement and control principles for the system were given. After an optimization algorithm for air-to-fuel ratio with constant step was introduced briefly, an adaptive optimization algorithm based on a PID controller was proposed, and then detailed design was presented. Advantages of the proposed adaptive optimization algorithm can be seen after comparison with a former algorithm. Approaches for the soft measurement of airflow in a boiler system based on differential air pressure between the inlet and outlet of the air pre-heater and that of fuel were presented. The complete control strategies for the designed system were given. Implementation of the whole system by a Foundation Fieldbus, including structure design for the control system and soft configurations design for the proposed optimization algorithm, were presented at length. Control effects of the designed system were given, demonstrating tat the design of the whole system was a success by running it reliably for a long time. Some important conclusions on the proposed methodologies and designs in measurement and control using the fieldbus in combustion control were presented at the end of the paper.

A Neural Network Multiagent Architecture Applied to Industrial Networks for Dynamic Allocation of Control Strategies Using Standard Function Blocks

This paper presents a multiagent architecture applied to factory automation. These agents detect faults in automated processes and allocate intelligent algorithms in field device function blocks (FBs) to solve these faults. We also present a dynamic FB parameter exchange strategy that allows agent fieldbus allocation. This architecture is a foundation for intelligent physical agents standard-based agent platform developed using Foundation Fieldbus technology. The aim is to enable problem detection activities, independent of user intervention. The use of artificial neural network (ANN)-based algorithms enables the agents to learn about fault patterns and adapt an algorithm that can be used in fault situations. Thus, we intend to reduce supervisor intervention in selecting and implementing an appropriate structure for FB algorithms. Furthermore, these algorithms, when implemented in device FBs, provide a solution at the fieldbus level, reducing data traffic between gateway and device, and speeding up the process of problem resolution. We also show some examples of our approach. The first is a neural network architecture change that allocates different types of neural networks in field devices without interrupting the fieldbus network operation. The second shows a multiagent architecture that implements the neural network change in a laboratory test process, where fault scenarios have been simulated.

Evaluation of Delays Induced by Foundation Fieldbus H1 Networks

The delays associated with the use of foundation fieldbus (FF) H1 networks within control loops are investigated in this paper. A Smar IF302 device, a Smar FI302 device, a DeltaV distributed control system (DCS), a Honeywell C300 DCS, and a National Instrument (NI) FF H1 workstation are used to implement test loops with the control-in-the-field architecture. Analytical and experimental evaluations are performed with a test loop using hardwired analog channels as a benchmark. Three segments of FF-H1-network-induced delays are identified, their analytical models are developed, and suggestions to potentially reduce the delays are provided. Furthermore, it is found that an unexpected additional delay of one macrocycle may be introduced, probably depending on whether the analog input (AI) block within the IF302 device is executed as scheduled. In conclusion, significant delays could be introduced if the traditional analog channels of a DCS are replaced by an FF H1 network.

Foundation Fieldbus Digital Technology: Today and the Future

Foundation Fieldbus technology has been in use for over a decade, yet the uptake within the United Kingdom lags other regions of the world. In part this is due to where construction is occurring and another reason may be a lack of understanding of the technology. This article will help you reduce your anxiety and reluctance to start taking advantage of industrial networks technology such as Fieldbus, Ethernet and Wireless.

Dependency on prioritized data in the delay analysis of foundation fieldbus

This paper introduces a mathematical model for analyzing the delay performance of time-critical and time-available data in the foundation fieldbus data link layer token-passing service. The mathematical model introduces the concept of virtual token rotation time to account for the dependency of the token rotation times on prioritized data in analyzing their data latency. The mathematical model also includes scheduled service for periodic data transmission to examine its effect on the performance of the token-passing service. The validity of the analytical model was verified using a simulation experiment.

A fieldbus simulator for training purposes

This article presents a fieldbus simulation platform and its remote access interface that enables a wide range of experiments, where users can configure operation sequences and procedures typical of Foundation Fieldbus systems. The simulation system was developed using LabVIEW, with requisites of deterministic execution, and a course management work frame web server called Moodle. The results were obtained through three different evaluations: schedule table execution, simulator functionality and finally, simulator productivity and achievement. The evaluation attests that this new tool is feasible, and can be applied for fieldbus automation systems training purposes, considering the robustness and stability in tests and the positive feedback from users.

Design and implementation of a new fuzzy PID controller for networked control systems

This paper presents a practical network platform to design and implement a networked-based cascade control system linking a Smar Foundation Fieldbus (FF) controller (DFI-302) and a Siemens programmable logic controller (PLC-S7-315-2DP) through Industrial Ethernet to a laboratory pilot plant. In the presented network configuration, the Smar OPC tag browser and Siemens WinCC OPC Channel provide the communicating interface between the two controllers. The paper investigates the performance of a PID controller implemented in two different possible configurations of FF function block (FB) and networked control system (NCS) via a remote Siemens PLC. In the FB control system implementation, the desired set-point is provided by the Siemens Human-Machine Interface (HMI) software (i.e, WinCC) via an Ethernet Modbus link. While, in the NCS implementation, the cascade loop is realized in remote Siemens PLC station and the final element set-point is sent to the Smar FF station via Ethernet bus. A new fuzzy PID control strategy is then proposed to improve the control performances of the networked-based control systems due to an induced transmission delay degradation effect. The proposed strategy utilizes an innovative idea based on sectionalizing the error signal of the step response into three different functional zones. The supporting philosophy behind these three functional zones is to decompose the desired control objectives in terms of rising time, settling time and steady-state error measures maintained by an appropriate PID-type controller in each zone. Then, fuzzy membership factors are defined to configure the control signal on the basis of the fuzzy weighted PID outputs of all three zones. The obtained results illustrate the effectiveness of the proposed fuzzy PID control scheme in improving the performances of the implemented NCS for different transportation delays.

Developing and implementing an open and non-proprietary device description for FOUNDATION fieldbus based on software standards

Support for interoperability and interchangeability of software components which are part of a fieldbus automation system relies on the definition of open architectures, most of them involving proprietary technologies. Concurrently, standard, open and non-proprietary technologies, such as XML, SOAP, Web Services and the like, have greatly evolved and been diffused in the computing area. This article presents a FOUNDATION fieldbus™ device description technology named Open-EDD, based on XML and other related technologies (XLST, DOM using Xerces implementation, OO, XML Schema), proposing an open and non-proprietary alternative to the EDD (Electronic Device Description). This initial proposal includes defining Open-EDDML as the programming language of the technology in the FOUNDATION fieldbus™ protocol, implementing a compiler and a parser, and finally, integrating and testing the new technology using field devices and a commercial fieldbus configurator. This study attests that this new technology is feasible and can be applied to other configurators or HMI applications used in fieldbus automation systems.

Advantages and safety features using foundation fieldbus-H1 based instrumentation & control for cryo system in accelerators

Large accelerator programme instrumentation and control for monitoring of large no. of parameters for cryogenic/cooling system. The parameters are Cryo Temperature, Vacuum, He Level and He flow etc. The circumference of the accelerator may vary up to several kilometers. Large size accelerators require huge cabling and hardware. The use of foundation fieldbus based Transmitters for measurement and Control valves field positioners for cryo system shall reduce the cabling, hardware, maintenance and enhance data processing and interoperability.Safety is an important requirement for efficient, trouble free and safe operation of any process industry such as cryo used in accelerators. Instrumentation and Control systems can be developed using Foundation Field Bus. The safety features in foundation field bus system can be achieved by use of intrinsic safe devices, fail safe configuration, minimize the hazard by distribution of control function blocks, short circuit preventers.Apart from above features, the significant cable reduction in the fieldbus system reduces the hazard due to electrical cable fire, which is considered one of the major risk in industry. Further the reliability in fieldbus can be improved by hot stand-by redundant power supply, hot stand-by redundant CPU, hot stand-by redundant network capability and use of link active scheduler.

Transmission of a Scheduled Message Using a Foundation Fieldbus Protocol

In the last decade, process instrumentation field devices such as sensors and actuators that have a direct contact with industrial processes have become increasingly intelligent. An important property of such intelligent field devices is their ability to be networked. The Foundation fieldbus (FF) is one of the most widely used fieldbus protocols for process instrumentation and control systems applications. This paper presents a study that validates the effectiveness of a new scheduling method that satisfies the performance requirements for a scheduled message using an FF protocol. Our scheduling method generates a schedule list that records the scheduled starting time and the scheduled period of each scheduled message. Then, it allocates scheduled message traffic to a bandwidth-limited fieldbus medium. As part of this study, an experimental model of an FF network was developed. The experimental results from our model confirmed that our scheduling method restricts the delay of a scheduled message to a prespecified bound.

DEPENDENCY ON PRIORITIZED DATA IN THE DELAY ANALYSIS OF FOUNDATION FIELDBUS

This paper introduces a mathematical model for analyzing the delay performance of time-critical and time-available data in the Foundation Fieldbus data link layer token-passing service. The mathematical model introduces the concept of virtual token rotation time to account for the dependency of the token rotation times on prioritized data in analyzing their data latency. The validity of the analytical model was verified using a simulation experiment.

204 フィールドバスを用いた熱プロセスの異常診断 : 第6報:熱交換器シェル内へのドレン滞留の診断方法について(セッション5 計測・モニタリングI)

The purpose of this study is to develop the monitoring and diagnosis methods for distributed energy system using fieldbus technology, which makes it possible to share much information of field devices. The authors constructed an experimental apparatus of a hot water supply process, which is one of the key components of distributed energy systems. The targets of abnormal conditions are not only air accumulation, which was also the target of previous works, but also drain accumulation in the shell. An algorithm of the process diagnosis based on monitoring process values and device operating conditions using the statuses in FOUNDATION fieldbus is developed and its effectiveness is confirmed experimentally.

ＰＣ方式によるフィールドバスシステム構築

従来のFoundation Fieldbus（以下，フィールドバス）システムは，専用の通信カードを実装可能なDCSを必要とするため，導入事例は新規のシステムに限られていた。そのため「導入コストが高い，システム立ち上げに必要な段取りが不透明，メーカ技術員の不足」などの問題点を抱えていた。本来の特徴である「マルチベンダ（対応機器であればメーカを問わず），プラグインディスプレイ（割付作業の簡素化），高信頼性（機器単体での制御確立）」と相反しているため，制御システムに依存しない構成を開発し，巻き返しを推進している。そういった流れの中で，2004年7月に「安価で誰もが扱えるフィールドバスの確立」を目指し，当時全く採用事例のない「汎用パソコン（以下PC）＋Ethernet＋SLD（リンキングデバイス）＋フィールド機器（制御は個々で行う）」という構成で排水嫌気性設備の新設プラントに設置した。本格稼働に無事漕ぎ着けることが出来たので，今日まで得られた知見と今後の展開について報告する。