Building systems technology in very general terms comprises electrical and electronic equipment and automation devices for industrial, commercial and private buildings. These equipment and devices range from bell transformers to the Dupline bus system. The SI system (current impulse system) is a control and automation system for fixed wire installations. The wide range of function modules and the logic through the wiring make the implementation of a number of control tasks possible, such as daylight and time-linked switching of electrical consumers (e.g. luminaires, roller shutters, blinds), dimming functions for low-voltage and DALI luminaires or even the protection of roller shutters and awnings from wind and rain. Individual, group and central commands can be added as desired. The SI system functions completely without PC programming, and can therefore be installed conventionally. As the wiring corresponds to the controls with relay or contactor circuits as far as possible, the project design and commissioning work is very reduced. Thanks to the consistent use of the 24 V DC control and supply voltage and the strict separation between the SELV and low-voltage side, the components are compact, reasonably priced and not sensitive to interference.