Building automation is constantly evolving, and the KNX protocol is one of the pillars of this transformation, being widely used for controlling and monitoring devices in smart homes and buildings. An essential component of the KNX system is the power supply, which not only provides energy but also enables communication between the devices connected to the bus. In this article, I will explain in detail how a KNX power supply works, highlighting its features and the importance of the signal generator and galvanic isolation.