RBFU 3.10 has 12 digital inputs. It is mountable on DIN rail. Inputs are potential free contacts. The unit is connected to the Ringbus master controller via a 4 wire ring bus communication. Each unit has a predefined address and therefore has not to be addressed during the system commissioning. RBFU 3.10 unit is able to work without 230 V, but then it is only sending information about its power supply condition and is not able to read inputs.