The DTE transmits when it sees CTS up. When the station has finished its transmission, it drops RTS and the modem drops CTS and carrier together. Note that the transmit and receive clock signals do not have to be the same, or even at the same baud rate. Glossary of Abbreviations etc. DCE Data Communications Equipment eg.
Some applications require more pins than a simple async.
Tail Circuit Cable Null Modem Cable for Async or Sync data Cross Pinned cables for Async data. Signal Description Abbr. Clear To Send CTS 8 Request To Send RTS jump to all types of cable pin outs diagrams page RS-232 Specs. Level 5 cable can also be used but for best distance use a low capacitance data grade cable. The standard maxim length is 50' but if data is async you can increase that distance to as much as 500' with a good grade of cable.