The utility model provides a serial communication port, , including the dust cover, the dust cover is U type groove, and U type groove tip both sides outwards have epitaxial board respectively, fixed surface has special trachea way under the epitaxial board, special trachea is said and is communicate with outside air supply line. The utility model discloses be fixed with special trachea way in extend board and U type tank bottom portion, the special gas in the air supply line can directly convey the air feed through special trachea way, and the dust cover becomes a body structure with special trachea way, and fixed stable difficult emergence is squinted or is out of shape, can effectively lengthen the life of special air pipe, reduces and safeguards, keeps coating process's long -term stability.