Systems and methods for coupling a respiratory support circuit (5, 5a) to a pressure generator (140) include multiple flow paths 13,17) for corresponding modes of operation. A first flow path (13) for a first mode of operation couples fluidly between the pressure generator, through a control port (12) and a circuit port (14), to an exhalation limb (20) of a dual-limb configuration of a respiratory support circuit. A second flow path (17) for a second mode of operates couples fluidly between the pressure generator, through a control port (16) and a circuit port (18), an exhalation valve (21) of a single-limb configuration of the respiratory support circuit.