Dear friends, I am Electrician Old Li. In our modern factories, PLCs are the “central nervous system” and hold a very important position. But did you know? It seems complex and mysterious, yet the workflow actually consists of three steps: input sampling, program execution, and output refreshing. However, within these three steps lies a lot of knowledge, creating a gap between novice and experienced engineers, causing many engineers to struggle upon first contact. Today, Old Li will have a good chat with everyone.