All vehicles registered after 9 December 2006 must have a digital tachograph installed.

Digital tachographs consist of a tachograph head unit, a motion sensor and the wire between them. The head unit is the visible part and is placed near the driver. It is the size of a car radio and may be integrated into the instrument panel. The motion sensor is installed on the gearbox and records driving time and rest periods as well as speed. 

The tachograph head and the motion sensor communicate with each other. They have mechanisms to detect if the connections are broken, or if there is an attempt to change them. The head unit and the motion sensor are connected as a pair, and the signals between them are encrypted. Attempts to tamper with cables, or install other equipment between them, are recorded and stored in the head unit.

The purpose of digital tachographs

The purpose of a digital tachograph is to ensure that the rules for driving time and rest periods are followed. This gives the driver better working conditions, increases road safety and ensures equal terms of competition between companies in the transport industry.

Using a digital tachograph

The tachograph records the vehicle's activities, along with a tachograph card. The card is used to record the driver's activities as well as work performed on the tachograph, and to inspect or download activities from the tachograph. 

The tachograph card is personal, it stores and transfers data from the tachograph.

Data stored in the digital tachograph

The tachograph head is the brain of the system. It stores all data, such as on driving, resting, other work, inspections and repair work, for about 12 months. It also stores information about violations of the rules, attempts to manipulate the tachograph, speeding, calibration and when data has been downloaded.

The tachograph head has a display with control buttons, two slots for tachograph cards, and a small printer for printing data on driving time and rest periods from either the tachograph head or the driver card.

The internal clock in the tachograph head uses Coordinated Universal Time (UTC) or Greenwich Mean Time (GMT). Data is registered in UTC time. The display shows the local time.