A data rail is required in a KNX bus system if the KNX devices to be installed in an electrical distribution (REG = DIN rail-mounted device) dispose of pressure contacts on their rear side. The data rail provides a connection between the KNX bus and the KNX device by means of the usual KNX bus terminal. The data rail is glued into the DIN rail (self-adhesive). Often, data rails with mounted data rail connector are offered, so no connector must be ordered separately. eibabo sells data rails in different lengths depending on the required space or horizontal pitches (HP) or space units (PLE). One space unit is standardized and equals 18mm, the width of a normal circuit breaker. The data rail consists of 4 horizontal conductor tracks. The assignment according to KNX standard, including the terminals at the data rail connector is from the top to bottom as follows: Yellow: + 24V, red: + KNX bus, black: - KNX bus, white: 0V. The outer conductor tracks / connector terminals (yellow and white) supply the KNX lines via a separate KNX choke. A data rail should not be shortened! To protect remaining blank spaces on a data rail, cover strips can be snapped on. KNX data rails have existed since the beginnings of the European Installation Bus (EIB) and are increasingly disappearing from the market, although the data rail is actually very practical and convenient. As far as the production is concerned, pressure contacts on the rear side are much more expensive and the reason, why almost all manufacturers have switched to direct bus connection contacts (bus terminals). The advantages of the data rail are the much better overview of the electrical distribution, reduced wiring costs (KNX bus) between KNX devices and the reduction of wiring errors (+/- reversed). However, it can be assumed that there will be fewer KNX devices with pressure contacts in the future. In this eibabo category you will find data rails, cover strips for data rails, data rails with connectors and data rails for deep and shallow top hat rails of the brands Berker, Hager and Siemens.