The switch actuator receives telegrams from sensors via the Instabus and switches electric loads with its relay contact. In addition, the device has two extension inputs that depending on parameter settings, can act directly on the switching output (local operation of the switching output by input A) or alternatively also as binary inputs on the Instabus. The connected potential- free switch or push button contacts are read in via a common reference potential on the switch actuator. As binary input, telegrams can be transmitted for switching or dimming, for Ve- Venetian blind control, value setting or scene recall / save.