According to a concept of the invention, there is proposed a communication interface that enables communication and power transfer between a luminaire and a connectable module. The communication interface comprises a driver circuit which generates an AC power supply for a primary winding, the primary winding being magnetically couplable to a secondary winding for powering the connectable module. A data sensing arrangement is adapted to detect a variation in the voltage/current of the primary winding which has been induced by the secondary winding. A control arrangement selectively couples a first and second DC input, upon which the AC power supply is based, together or to a common voltage.