Data transmission unit for the synchronous transmission of data (D, D') between two communication partners (K1, K2), of which one acts as the sender and one as the receiver, with - an event monitor (11, 11'), which monitors the occurrence of at least one predefined event on the sender side, and in the event that one of these events occurs, displays the event as an event occurring on the sender side (E s, E s ') during the occurrence of the event, - a clock (13, 13') connected to the event monitor (11, 11') with an adjustable clock frequency, which generates a transmission clock (clk, clk') with a transmission clock rate (f s, f s '), which, while one of the events (E, E') occurs, is equal to an event-specific transmission clock rate (f E1, f E2, f E1') which is assigned to the event (E s, E s ') that occurs, and, during an event-free period, is equal to a base clock rate (f 0) which is different to all the event-specific transmission clock rates (f E1, f E2, f E1'), - a transmission unit, -- which transmits the data signals (DS, DS') corresponding to the data to be sent (D, D'), with the transmission clock rate (f s, f s') from the sender to the receiver, and -- which transmits the transmission clock (clk, clk') from the sender to the receiver, and - an event detection unit (21, 21') connected to the transmission unit on the receiver side, which detects an occurrence of one of the events (E, E') on the sender side using the transmission clock rate (f s, f s ') of the transmission clock (clk, clk'), and determines and outputs the event (E s, E s ') when the event occurs. - an event monitor (11, 11'), which monitors the occurrence of at least one predefined event on the sender side, and in the event that one of these events occurs, displays the event as an event occurring on the sender side (E s, E s ') during the occurrence of the event, - a clock (13, 13') connected to the event monitor (11, 11') with an adjustable clock frequency, which generates a transmission clock (clk, clk') with a transmission clock rate (f s, f s '), which, while one of the events (E, E') occurs, is equal to an event-specific transmission clock rate (f E1, f E2, f E1') which is assigned to the event (E s, E s ') that occurs, and, during an event-free period, is equal to a base clock rate (f 0) which is different to all the event-specific transmission clock rates (f E1, f E2, f E1'), - a transmission unit, -- which transmits the data signals (DS, DS') corresponding to the data to be sent (D, D'), with the transmission clock rate (f s, f s') from the sender to the receiver, and -- which transmits the transmission clock (clk, clk') from the sender to the receiver, and -- which transmits the data signals (DS, DS') corresponding to the data to be sent (D, D'), with the transmission clock rate (f s, f s') from the sender to the receiver, and -- which transmits the transmission clock (clk, clk') from the sender to the receiver, and - an event detection unit (21, 21') connected to the transmission unit on the receiver side, which detects an occurrence of one of the events (E, E') on the sender side using the transmission clock rate (f s, f s ') of the transmission clock (clk, clk'), and determines and outputs the event (E s, E s ') when the event occurs.