Learning PLC programming, we often encounter the sequential control, but how to make plc ladder diagram，
there is example Shuttle program.
The initial state of the car parked in the middle (limit switch X0 is pressed, the normally open contact closure),Press the Start button (X3 closed), the car began to follow the direction shown to reciprocate when you need to stop, press the stop button (X4 closed), stop automatically when the car moves to the middle position. Here all the buttons and travel switches are normally open contacts are connected to the input terminals of the relay.
there is example Shuttle program.
The initial state of the car parked in the middle (limit switch X0 is pressed, the normally open contact closure),Press the Start button (X3 closed), the car began to follow the direction shown to reciprocate when you need to stop, press the stop button (X4 closed), stop automatically when the car moves to the middle position. Here all the buttons and travel switches are normally open contacts are connected to the input terminals of the relay.
PLC ONE 