RsLogix 500 Training - Program Flow, Which Rung Wins Part 1

In this lesson we are going to learn which rung "wins" when you have two output instructions addressing the same output.  This is the first of a three part series.

In the Rslogix 500 - Online Edits lesson you were left with a program that had multiple output instructions addressing the same physical output.  This is called having duplicate outputs. You may have heard there are "rules" that don't allow you to do this.  Some instructors even take points off if you do this even if your program works.  We are not saying this is a good practice, but "rules" are usually rooted in a lack of understanding of how a PLC handles a certain situation.  

The first part of this should be done without the PLC or RsLogix 500.  Looking at the two rungs in the image below, answer the questions below the image.


Take the time to think about the questions above.  Once you have answered the questions above, continue to the RsLogix 500 - Program Flow, Which Rung Wins Part 2 lesson.

Next Steps

Go to the Allen Bradley RsLogix 500 PLC Training PLC Training Getting Started Lesson series to select your next lesson.  There are also many other Lesson Series on PLC Programming and Industrial Automation.