Editing Ladder logic (section)

===Logical AND with NOT===
{| 
|<pre>
 ------[ ]--------------[\]----------------( )
   Close door      Obstruction         Door motor
</pre>
|}
The above realizes the function: Door motor = Close door [[logical AND|AND]] [[logical NOT|NOT]] Obstruction.

This circuit shows a push button that closes a door and an obstruction detector that senses if something is in the way of the closing door. When the normally open push button contact closes and the normally closed obstruction detector is closed (no obstruction detected), electricity is able to flow to the motor which closes the door.