The present invention relates to an extracorporeale interface unit (8), for an intravascular measurement system for measuring at least one physiological, or other, variable in a living body, adapted to generate a sensor signal in response of the variable. The interface unit (8) comprises a sensor interface circuitry (6) adapted to interface a sensor wire configured to be inserted into the living body and provided with one or many sensor element(s) at its distal region. The sensor interface circuitry (6) comprises a measurement unit (9) adapted to generate the measured data of the variable as a sensor signal. The interface unit (8) further comprises a control unit (1) adapted to control and supervise the different functions of the interface unit (8), wherein the different functions are performed by predefined tasks (T1, T2 . . . TN) during consecutive control periods CP having the same time duration.