I have used terminator resistors (120 ohm) and a restistor to + and - (470 ohm) and have hardly any garbage on the line. Furthermore I use UTP-cable CAT 5. Before I send a command I first do a CR/LF to get a clean buffer. Check http://members.home.nl/bzijlstra
and then the Benbus part. You can also check the book Serial Port Complete from Jan Axelson. ISBN 0-9650819-2-3 Published by Lakeview Research.