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Teaching Finite State Machines (FSMs) as Part of a Programmable Logic Control (PLC) Course

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2017 ASEE Annual Conference & Exposition


Columbus, Ohio

Publication Date

June 24, 2017

Start Date

June 24, 2017

End Date

June 28, 2017

Conference Session

Electrical and Computer Division Technical Session 8

Tagged Division

Electrical and Computer

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Paper Authors


Curtis Cohenour P.E. Ohio University

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Dr. Cohenour is an Assistant Professor in the Ohio University Engineering Technology and Management Department, in Athens, Ohio. He received a Bachelor of Science degree from West Virginia Institute of Technology in 1980, a Master of Science degree from Ohio University in 1988, and a Ph. D. in Electrical Engineering from Ohio University in 2009. He is a registered professional engineer in West Virginia, and Ohio.

Dr. Cohenour has worked in Industry as an electrical engineer and project manager. He joined Ohio University in 2002 as a research engineer working for the Ohio University Avionics Engineering Center. He has worked on projects covering a wide variety of avionics and navigation systems such as, the Instrument Landing System (ILS), Microwave Landing System (MLS), Distance Measuring Equipment (DME), LAAS, WAAS, and GPS.

His recent work has included research with the Air Force Research Laboratory in Dayton, Ohio, aimed at understanding and correcting image geo-registration errors from a number of airborne platforms.

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Industrial control courses in Electrical and Computer Engineering (ECE) include programming of Programmable Logic Controllers (PLCs). Text books are available to support these courses but few provide any content on Finite State Machines (FSMs). This is unfortunate because a great deal of PLC applications in industry involve sequence logic which lends itself to the FSM.

A FSM consists of a defined (finite) number of states that a system can be in, and well defined rules for how the system moves from one state to the next. The FSM can perform entry chores, exit chores, and state tasks. Inputs and calculations made within the state define the movement from state to state. The action that results from an input may depend on the current state. A PLC is a computer that solves relay logic also referred to as ladder logic. PLCs are typically connected to limit switches and solenoid valves and provide low level control functions. Supervisor computer systems may also direct the action of a PLC.

The course content described in this paper offers the authors industry tested implementation of the FSM for PLC implementation. The FSM connects the PLC input devices to the PLC output devices in a straight forward manner that makes the system easier to understand for engineers and maintenance personnel.

Students learn not just how to program a PLC, but how to create ladder logic that provides a reliable and maintainable PLC solution. PLCs are ubiquitous in industry and students with experience and ability are in high demand.

Cohenour, C. (2017, June), Teaching Finite State Machines (FSMs) as Part of a Programmable Logic Control (PLC) Course Paper presented at 2017 ASEE Annual Conference & Exposition, Columbus, Ohio. 10.18260/1-2--28917

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