Sensor consists of an RFID-reader and a unique door tag. Door opening sensor is designed on the basis of non-contact technology, and uses radiofrequency identification. This method has advantages over the existing access control technology. The tag on the door has a unique ID-code that is impossible to fake; this ensures high protection from personnel manipulations. High reliability of the equipment achieved through its construction, which endures the influence of humidity and aggressive environments. Sensor operates through noise immune interface RS-485.