All Digi Serial ports are DTE. In order to select the correct cable to connect to a device on a serial port you must know if the device port is DTE or DCE. Data flow on DTE ports is as follows:

RI Input
DSR Input
RTS Output
GND
TXD Output
RXD Input
SG
CTS Input
DTR Output
DCD Input

When connecting DTE devices together, such as terminals or printers to a Digi serial port, remember inputs go to outputs. Connecting two inputs or two outputs does nothing. The data flow on DCE ports in opposite the flow of DTE ports. When connecting a Digi serial port to a DCE device such as a modem, connect like signals together. (ie. RXD to RXD, TXD to TXD and so on.) This takes priority over color or pin number, although pin number standards should be maintained where they exist.