2006-1830: FIELDBUS NETWORKS TOPIC IN INSTRUMENTATION AND CONTROL SYSTEMS COURSES Sri Kolla, Bowling Green State University Sri Kolla is a Professor in the Electronics and Computer Technology Program at the Bowling Green State University, Ohio, since 1993. He worked as a Guest Researcher at the Intelligent Systems Division, National Institute of Standards and Technology, Gaithersburg, MD, 2000-‘01. He was an Assistant Professor at the Pennsylvania State University, 1990-‘93. He got a Ph.D. in Engineering from the University of Toledo, Ohio, 1989. His teaching and research interests are in electrical engineering/technology area with specialization in artificial intelligence, control systems, computer networking and power systems. He is a senior member of IEEE and ISA. Joseph Mainoo, Bowling Green State University Joseph Mainoo is a graduate student in the Master of Industrial Technology degree at the Bowling Green State University, Ohio. He received his B.S. in Electronics and Computer Technology from the Bowling Green State University, Ohio, in 2004. He also has a Diploma in Management Information Systems from the Institute for the Management of Information Systems, London, UK. His academic interests are in the areas of information technology and electronics. He is a student member of ISA. Page 11.642.1 Page © American Society for Engineering Education, 2006 Fieldbus Networks Topic in Instrumentation and Control Systems Courses Abstract Fieldbus networks are digital, two-way, multi-drop communication links that are used to connect intelligent control devices. These are currently introduced in the industry to replace the traditional 4-20 mA point-to-point connections. It is important to integrate fieldbus networks topic in technology courses to align the curriculum with the current industrial practices. This paper, therefore, presents how the fieldbus networks topic is integrated into ECT 441 Instrumentation and ECT 453 Digital Computer for Process Control courses in the Electronics and Computer Technology Program (ECT) at the Bowling Green State University (BGSU). The paper first gives an overview of the current state of fieldbus networks in the industry. It lists various advantages of using fieldbus networks over point-to-point connections for instrumentation and control system implementations. The generic communication protocol model is discussed and the deviations from this model for various fieldbus networks are identified. As an example of a fieldbus, Controller Area Network (CAN) overview is presented. CANoe, a CAN simulation software is outlined. Details of a CAN bus based laboratory development at BGSU that uses CANoe software and the CAN hardware are also presented. I. Introduction Digital communication networks such as AS-I, CAN, Devicenet, Ethernet, Foundation Fieldbus, Profibus are increasingly used in instrumentation and control system implementations these days [1]. Sensors, controllers, and actuators are connected as nodes in these networks instead of hardwiring the devices with point-to-point connections. These networks, collectively called fieldbus networks, reduce system wiring and provide easy system diagnosis and maintenance. It is important to integrate fieldbus networks topic in instrumentation and control system courses in order to make the content of these courses up-to-date with the current industrial practice. There is significant literature available on fieldbus networks [1-3]. Hulsebos has been maintaining a comprehensive web site since 1999 that lists various fieldbus networks with links to official web sites of each fieldbus organization [4]. Integration of fieldbus topics into undergraduate curriculum is slowly taking places at various institutions. For example, Franz [5] reported the development of a National Center for Digital and Fieldbus Technology (NCDFT) under an NSF grant at Lee College, Texas. Also in Reference [6], Müller and Max Felser described how fieldbus concepts are adopted in control technology curriculum in Switzerland. A weather station instrumentation experiment that uses digital and wireless communication concepts was adopted in a Computer Engineering curriculum at University of Oviedo, Spain [7]. The concept of fieldbus networks such as Devicenet are also introduced in PLC courses at several institutions [8-11]. Further more, some institutions such as University of Main revised its traditional power courses into industrial automation and communication courses [12]. An in depth understanding of the literature reveals that there is still a greater need to integrate fieldbus 11.642.2 Page topic into undergraduate engineering and technology curriculum. This paper, therefore, presents how the fieldbus networks topic is integrated into ECT 441 Instrumentation and ECT 453 Digital Computer for Process Control courses in the ECT Program at BGSU. Section II describes the content of instrumentation and process control courses. Section III gives an overview of the current state of fieldbus networks in the industry. It lists various advantages of using fieldbus networks. The generic communication protocol model is discussed and the deviations from this model for various fieldbus networks are identified. An overview of CAN bus network is also given in that section. CANoe software, developed by Vector CANtech, is outlined in Section IV. Details of CAN bus based laboratory development at BGSU are presented in Section V. Concluding remarks are offered in Section VI. II. Instrumentation and Process Control Courses at BGSU The ECT program at BGSU offers instrumentation and process control courses in its undergraduate curriculum [13]. A graduate instrumentation and process control course is also offered in the Master of Industrial Technology program of the College of Technology. All of these courses have a laboratory component integrated with the lectures. The laboratory activities in these courses emphasize industrial sensors, actuators and data acquisition to investigate the behavior of the measurement and control systems. National Instrument’s NI-ELVIS station with LabVIEW software is used in these laboratory activities. Students do mini-projects using the PC-based laboratory workstations that integrate NI-ELVIS shown in Figure 1. These projects enable the students to analyze, design, build and test complete instrumentation and process control systems. Through this approach, students obtain exposure to many real problems associated with instruments such as loading, grounding, interaction between different blocks, nonlinearity, effects of ambient conditions and interfacing real world sensors and actuators to computers. Also, experience is gained in developing and testing process control algorithms using physical process simulators. 11.642.3 Page Figure 1. NI-ELVIS Experimental Setup. In the instrumentation course, some of the laboratory projects performed by students include i) temperature measurement system using RTD, ii) position measurement system using LVDT, and iii) weight measurement system using strain gauge. The projects performed in the process control course laboratory include, i) Temperature control using ON/OFF control mode, ii) PID controller for liquid level control system, and iii) speed control of dc motor. The temperature control system experiment described below is used as an example for the process control laboratory [14]. The objective of the temperature control experiment is to maintain the temperature inside a wooden box at some desired set-point value, within neutral zone limits, using a two-state- controller mode. The wooden box is heated with a light bulb. The temperature is measured using LM34 solid-state temperature sensor based circuit, which gives 10mV/°F. A signal conditioner is designed to modify the voltage corresponding to 50 to 150 °F to analog input voltage range of -10 V to +10 V. The output of the signal conditioner circuit is connected to an analog input channel on the NI-ELVIS station. When the temperature differs from the set-point value (with ± neutral zone), it results in the high-limit and the low-limit, and a fan is turned on and off accordingly. An analog output channel of the NI-ELVIS is connected to the solid-state relay (SSR) that controls the operation of the fan. Figure 2 gives a schematic diagram of this experiment. Figure 2. Schematic Diagram of the Temperature Control Experiment. A closer look at the content of the instrumentation and process control courses reveals a need to incorporate recent topics such a fieldbus networks. Also, current industrial employers are looking for employees with a background in fieldbus networks. It is therefore necessary to provide some knowledge in fieldbus networks to our students. 11.642.4 Page III. Fieldbus Concepts Fieldbus networks are digital communication networks in which sensors, controllers, and actuators are connected as nodes instead of hardwiring the devices with point-to-point connections. The advent of fieldbus technology has made possible a wide range of new capabilities. These new capabilities provide benefits that in turn translate into savings. The following are some of the advantages of fieldbus networks [1]: 1. Interoperability: the ability of a device to work together with other devices. This enables easy and tighter integration of devices from different manufacturers. 2. Greater system functionality: an unlimited number of parameters can be accessed from a device. This allows multiple measurements and a wide range of features to be crammed into advanced device firmware and accessed