Symbol Spectrum24 AP-4100 Series Product Reference Manual page 26

Introduction
The DB-9, 9-pin, RS-232 serial port provides a UI (User Interface)
connection. The UI provides basic management tools for the AP . The serial
link supports short haul (direct serial) or long haul (telephone-line)
connections. The AP is a DTE (Data Terminal Equipment) device with male
pin connectors for the RS-232 port. Connecting the AP to a PC requires a
null modem cable.
18 AP-4100 Series Access Point Product Reference Guide