Abstract: A method and device are provided for the asynchronous transmission of data packets, consisting in transmitting messages in the asynchronous mode, the messages comprising a beginning of message character, a character designating the address of the addressee, possibly a character designating the address of the sender, possibly characters containing the significant information of the message, and an end of message character. The beginning of message and end of message characters are formed of a continuous pulse of a length equal to the number of the significant bits of a normal message character increased by two bits. Such a pulse is recognized by the frame control circuits, in the case where the characters are without parity bits; they are recognized by the parity control signals in the case where the characters are provided with parity bits.