Now that you know how a single rung is executed, and how its results are stored in memory, you should be ready to learn about how a PLC executes a program as a whole.
As discussed in previous videos, the PLC executes rungs in order from top to bottom, and each rung is evaluated from left to right.
However, what happens when the PLC gets to the end of the program? The answer: It starts over from the beginning!
A PLC program is executed similarly to how an infinite loop in a typical programming language is executed.