Craig, one more point; you say your concern is to ensure your data is received correctly; RTS/CTS handshaking will never guarantee that - at best it will prevent receiver overruns, but there are many other ways your data can be waylaid. You must implement some kind of error-checking and acknowledgement protocol between the two ends to ensure correct receipt of data. How complex this has to be depends on what you are doing. Clyde -- Clyde Smith-Stubbs | HI-TECH Software, | Voice: +61 7 3300 5011 clyde@hitech.com.au | P.O. Box 103, Alderley, | Fax: +61 7 3300 5246 http://www.hitech.com.au | QLD, 4051, AUSTRALIA. | BBS: +61 7 3300 5235 ---------------------------------------------------------------------------- For info on the World's best C cross compilers for embedded systems, point your WWW browser at http://www.hitech.com.au, or email info@hitech.com.au