A New Approach To Teaching Programable Logic Controller Programming

The Programmable Logic Controller (PLC) is used widely in industries to control processes and manufacturing systems. There are several analytical approaches for developing PLC programs which are state diagrams, Petri Network and diagrams, truth tables, and Boolean algebra. All of these approaches are useful in developing a sequence of controlling PLC programs in complex systems, but none of these lead to a full automated way of developing a program. In the traditional way of teaching PLC programming such as the state diagram, a diagram is first constructed showing all the possible paths the process can take. Then the Boolean conditions necessary for each path are added. The diagram is then converted to a PLC program and tested. Changes are made to the Boolean conditions and then the new program is tested again. This process of trial and error is continued until a bug free program is developed. This trial and error step does not lead to an automated program development technique. This paper proposes a new approach to controller design and sequence control programming to be used by teachers and industrial trainers. This new method would be a useful tool for teaching beginners a faster way of developing a PLC program. This new approach combines some of the key concepts from various techniques to deliver a novel but effective automated method. This new technique translates in two easy steps truth tables into Ladder Logic Diagram, which is the most common graphical language for PLC programming. An example of a typical hydraulic station was used to demonstrate the analytical method. This example shows that this new analytical and systematic approach can be used to develop the sequence control program of complex systems. This new teaching technique has been applied to engineering technology students. A research study was conducted to verify the usefulness of this method. The study separated engineering technology students in two groups. One group was taught PLC programming in the traditional way, while the other was taught using the new method. Using the same test, the results showed that the group exposed to the new technique spent less time programming, when compared the other group.