June 14, 2009
June 14, 2009
June 17, 2009
Laboratories in Electrical and Computer Engineering Technology
14.748.1 - 14.748.10
Integrated Simulation and Assessment Software for Programmable Logic Controller Laboratory Instruction Abstract
Providing students with engaging laboratory experiences in sequential process control is challenging. Simple training devices that use lights and switches to teach basic principles fail to capture the complex interactions of industrial processes. Scale model process simulators are bulky and expensive to purchase and maintain in an educational environment. Laboratory exercises that represent process control responses accurately and engage students visually are the most relevant. Realistic industrial processes demonstrate typical automation systems to expand student programmable logic controller knowledge. This paper presents process simulation and assessment software for gathering student performance data. Students develop programs that reproduce control actions demonstrated by the software. An associated assessment module tests student understanding. Results from a student survey measuring the software effectiveness indicate the value of this laboratory experience as a learning tool.
The programmable logic controller (PLC) is a fundamental part of modern industrial automation systems such assembly lines, robots, and machine tools. These devices implement sequential control schemes using a variety of programming methods. Ladder logic uses symbolic instructions similar to schematic symbols to program control applications. Developing students’ sequential control design abilities and honing PLC programming skills requires a wide variety of exercises with increasing complexity using a number of subsystems. Industrial sequential control systems involve large, expensive, mechanical systems that include hydraulic, thermal, pneumatic, fluid, and electrical subsystems. These systems are costly and difficult to maintain in an educational setting.
Educational laboratory equipment vendors sell PLC trainer systems that are less costly and have simple interfaces made of lights and switches. These trainer systems can demonstrate basic programming principles but fail to show the interactions of complex industrial automation systems. Commercial software to simulate electromechanical systems and link to PLCs lacks debugging functions that help students learn program design.1
Student performance assessment is a critical part of any educational experience. Instructors can evaluate student performance in PLC programming by observing student software demonstrations, assigning written reports that document design and program details, and conducting quizzes. These methods require extensive development and oversight, and are difficult to integrate into an overall assessment plan that meets current ABET-TAC accreditation requirements.2
Simulator developers have used a variety of technologies to create automation and control devices for education. A microcontroller that communicates with a PC through a serial interface was selected by one team as the preferred simulation hardware tool.3 Simulator software written in Pascal and C handled both analog and digital signals. Other groups utilized commercial
Spezia, C. (2009, June), Integrated Simulation And Assessment Software For Programmable Logic Controller Laboratory Instruction Paper presented at 2009 Annual Conference & Exposition, Austin, Texas. 10.18260/1-2--4554
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