KNX coupler, to be used for data exchange between two KNX lines. It may be used as: line coupling unit (for coupling one line to a main line) - backbone coupling unit (for coupling a main line to the backbone line) - repeater (for coupling two segments of the same line). Bus connection using a red-black KNX connector. SELV 29 Vd.c. supply voltage from KNX bus. Fitting on DIN rail. Size: 2 DIN modules.