All RS232 devices that use a DB-9 connector should conform to the standard TIA/EIA-574. The device should be either DCE or DTE. DCE devices should have a female DB-9 connector, and DTE devices should have a male DB-9 connector. For a description of pin outs for the RS232 DB-9 connector see attached document "PinoutStndrds.pdf" from Cisco (page 2). Any RS232 device that has a DB-9 connector and conforms to this standard will connect easily to the Digi PKG-R (PKGR) or development kit radio modems.
These guidelines can help in understanding the terminology:
Find more information and detailed RS232 connection drawings in the PKG-R product manual.