A method for serial data transmission between a position-measuring device and subsequent electronics over a bidirectional data channel includes transmitting data in data frames and in encoded form in accordance with a data transmission code. The data transmission in each case is initiated by an interface unit at a transmitter end with a start sequence having an encoding scheme that at least partially differs from an encoding scheme of a remainder of the data frames. After a reversal of data direction, an interface unit at a receiver end detects a beginning of the data transmission in each case by detection of the start sequence.