An interface device having a first and second data terminal configured for the communication of data in duplex mode, with one of the first and second data terminals always assigned to each direction of the communication, the first and second data terminals configurable during operation such that, in a first mode of operation, the first data terminal is configured to send but not to receive data and the second data terminal is configured to receive but not send data, while in a second mode of operation the first data terminal is configured to receive but not to send data and the second data terminal is configured to send but not to receive data.