Abstract: The interface circuit serves for connecting two apparatus by way of a bidirectional bus which comprises a data lead for transmitting data and a cycle lead for transmitting a cycle signal. The interface circuit consists of a circuit arrangement provided at each apparatus, which comprises a separating means for separating the data signal on the data lead and the cylce signal on the cycle lead in each case into a transmitting and a receiving branch, and which furthermore comprises in each case for the data lead and the cylce lead a bus driver having a differential transmitter and receiver. The data signals and cylce signals between the apparatus are transmitted via differential leads.