An interface module for a communication control device of a subscriber station. The interface module has at least one configuration register for configuring the bit time of a first communication phase of a frame and/or the bit time of a second communication phase of the frame by means of which frame messages are exchanged between subscriber stations of the bus system, and a modulator for modulating a transmission signal to form a modulated transmission signal which has the bit time of the second communication phase, which bit time is configured in the at least one configuration register and differs from the bit time of the first communication phase. The interface module is configured to output the transmission signal input into the modulator to a transmitting/receiving device of the subscriber station.