Base unit U5 is the extremely simple and reliable device. It has two operating modes. The mode 1 - "a mark on pressing" - is the most economic from the point of view of consumed energy. When the station is in a sleep mode (real time clock work only), pressing the button activates it and then the punching data is transmitted to the card (activation time is less than 0.01 sec.). A mode 2 - "continuous interrogation". In this mode the station continuously searches for a card, and, in case of success, writes down the data. In both modes the sound and light signals are served as a confirmation of punching being made successfully.