June 12, 2005
June 12, 2005
June 15, 2005
10.349.1 - 10.349.8
Controlling a LEGO Student Factory Using PLCs
R. M. Nelms, Brian McGee, Nuno Delfino, Calvin Cutshaw ECE Department, Auburn University email@example.com
Programmable logic controllers (PLCs) are used extensively in manufacturing, in process control, and in automated testing. The PLC industry generates revenues of approximately US $1.4 billion from hardware, software, and related services1. In addition, the world-wide PLC market is expanding. Over one hundred companies produce a wide variety of products for this market. As a result, PLC programming experience can be a very marketable skill for students entering the workforce. Based on feedback from students interviewing for jobs, a PLC-based course with laboratory was developed to provide students with basic PLC skills.
The laboratory was constructed around the Allen-Bradley SLC 5/03 processor and RSLogix500 software. Six identical lab stations contain an a SLC 5/03 processor, an 8-bit discrete input module (Allen-Bradley 1746-IB8), an 8-bit discrete output module (Allen-Bradley 1746-OB8), and an analog combination module with 2 A/D channels and 2 D/A channels (Allen- Bradley 1746-NIO4V). The processor, modules, and power supply are housed in a seven-slot rack, which allows room to add other modules in the future. The RSLogix500 software is installed on a generic PC, which is connected to the PLC via a serial connection. Students develop their ladder logic programs in the RSLogix software and download them via a serial connection between PC and the PLC. Programs may be uploaded from the PLC to the PC over this same connection.
One of the goals of the laboratory was to provide the students with an end-of-term project that would simulate conditions in an industrial environment. Limited laboratory space and financial resources prevented the acquisition of actual industrial equipment. Many educators have utilized LEGO products for projects and laboratories2-5. A LEGO Student Factory was constructed as the basis for the end-of-term project and is shown in Figure 1. A crane is utilized to lift blocks from the floor to the top of the laboratory table. Once a block has reached the proper height, a limit switch turns off the crane motor. Next the pusher arm transfers the block from the lifter plate onto a conveyor constructed using LEGOs. A proximity sensor determines when the block is moved to the conveyor belt and turns on the conveyor belt drive motor. The blocks are sorted, using a sorter car constructed from LEGOs, into two bins based on a predetermined sorting criteria. After the block has been moved to the proper bin, the lifter plate is returned to the floor. This project requires the students to coordinate signals from 8 different inputs and control four dc motors - three with bidirectional capability.
“Proceedings of the 2005 American Society for Engineering Education Annual conference & Exposition Copyright 2005, American Society for engineering Education”
Delfino, N., & Cutshaw, C., & McGee, B., & Nelms, R. M. (2005, June), Controlling A Lego Student Factory Using Plcs Paper presented at 2005 Annual Conference, Portland, Oregon. 10.18260/1-2--15530
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