A user station is described. The user station includes a communication control device for transmitting and/or receiving messages to/from a bus of a serial bus system, a format switchover checking unit for checking whether the communication control devices of the bus system have switched over the format of the messages from a first format in a first communication phase to a second format for a second communication phase, and a transceiver device which, for transmitting in the first format, generates a first bus state for a first digital data state of the messages and a second bus state for the second digital data state of the messages so that the second bus state can overwrite the first bus state. The transceiver device, for transmitting in the second format, generates different bus states so that the bus states for the different digital data states of the messages cannot overwrite one another.