SETT OCH ANORDNING FOR INDIKERING AV TILLSTANDET FOR HISSKORGDORRAR

摘要

In a multi-deck underground cage (60) each door has a switch (18 to 24) fitted to it to provide a door-open or door-closed signal. The signals identify the respective door and are used to modulate an infrared carrier signal which is transmitted downwardly and reflected to a receiver (3). Information decoded from the carrier signal is displayed to indicate the status of each door at a location remote from the cage.