Ladder logic

Imagine you have a toy train that has to follow a certain path to deliver a tiny toy car to its destination. You can create a series of checkpoints that guide the train to its destination. Say, you have to start the train, move it forward, stop at a certain point, pick up the toy car, and then move it further to drop the car off at its destination.

Ladder logic works like a set of such checkpoints that guide a machine, like the toy train, to follow a specific set of steps to accomplish a goal. These checkpoints are called rungs in ladder logic. Ladder logic is used to program industrial machines like assembly lines and robots to do certain tasks.

To create a rung in ladder logic, you need two vertical rails, like the tracks of a train, called power rails. The left rail is called the power rail, and the right rail is the ground rail. You then add lines between the two rails, called rungs. The rungs contain instructions that tell the machine what to do.

Like the checkpoints in the toy train example, each rung in the ladder has a specific action it performs. For instance, if the ladder is set up to fill a bucket with water, the rungs would instruct the machine to turn on a valve, wait for the bucket to fill-up, and then turn off the valve.

In the simplest of terms, ladder logic is a set of instructions that helps a machine perform specific actions by following a logical set of steps.