Beginner lesson 2 of 17 · 20 min Free
Series and parallel contacts in ladder logic
Explain when a machine needs two on/off signals to be true at once, distinguish series from parallel in everyday language, then wire DoorClosed and Start to Lamp in the Workspace.
Before you start
- Helpful: the scan-cycle lesson. You can start here if you already know on/off tags and one scan.
Two inputs, one output
DoorClosed and Start are inputs, and Lamp is the output. The lamp should light only when both inputs are on.
In a row means both
Two contacts one after the other pass power only when both are on. People call that AND.
Side by side means either
Contacts on parallel branches pass power when either one is on. People call that OR, and this lesson does not use it.