Dataman S4 - Manual (Page 84)

DATAMAN S4 MANUAL
84 Baud Rates
RTS signal handshakes with your computer to
prevent it sending commands faster than S4
can action them.
When sending files, remember that most
computers cannot process data as fast as S4
can. To be safe, send at a slow baud rate or
connect the RTS handshake line. You can
usually see a bad transmission if you inspect
the file after receipt - some of the lines will be
short and contain bad characters.