A safety door switch monitors a door, gate or other movable barrier to detect if it's open or closed, or if an object is present in it.Safety door switches stop machinery or equipment when a safety door is opened.

AS-I door switches with guard locking have the function to keep moving protective equipment such as protective grating, protective guards and other covers closed as long as a dangerous state is present. They are operated in safe AS-i systems (Safety at Work) and function as electromagnetic interlocks with guard locking.

In combination with a guard and the machine control system this safety component prevents the safety guard from being opened while there is potential of exposure to a mechanical hazard. For the control system this means that switch-on commands which cause hazardous situations must become active only when the safety guard is in a protective position and the guard locking in locked position. The locked position of the guard locking must be released only when the hazardous situation is no longer present.