A couple of decades ago, well ... three decades, I guess, I worked with a dual door arrangement on a secure facility that used electric door strikes. You sent them a pulse from your controller and it released the latch for a predetermined time. A balanced magnetic switch determined whether the door was actually opened, and it, also, relied on a pulse, rather than a static signal to send status to the controller. These devices used simple timeouts to determine how long they were opened, though the balanced mag-switch pulse could be used to tell the electric strike to turn off, which meant it would latch in the locked position once the door was closed, irrespective of the timeout. That way, the door only opened once per electric strike activation.

RE