Year: 2020
Type: conference-paper
Abstract: Programmable logic controllers (PLCs) have been programmed using ladder logic since their introduction in the early 1970s.The programming technique most often used follows an empirical process that begins with entering the first rung to satisfy the first output requirement.Rungs continue to be entered leading toward a solution to the problem.At some point in the programming process the target system fails to respond as desired when the program is tested, and corrections are made to rungs in order to fix the problems.This process continues until a program solution is reached.The result is a program without sequential structure that is difficult to analyze and understand.With large PLC programs, troubleshooting the program when system problems develop is difficult.This paper describes how a technique called sequential function charts (SFC) is used in a twocourse sequence covering PLC programming.The SFC process adds structure to the PLC programming process and produces programs that are easy to analyze and troubleshoot.The paper also includes a description of the SFC process; types of problems assigned for student work; and the benefit derived from using SFC in a PLC programming laboratory or class.
DOI: 10.18260/1-2--9802
Author: James Rehg
Institution: Pennsylvania State University
Language: English
Subfield: Control and Systems Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2766007737