The serial port pinout is identical to a serial port found on a PC. This is referred to as a Data Terminal Equipment connection or DTE. It consists of a DB9 male connector with the following pinout:1 - Carrier Detect (CD) Incoming signal from a modem, 2 - Received Data (RD) Incoming Data , 3 - Transmitted Data (TD) Outgoing Data, 4 - Data Terminal Ready (DTR) Outgoing handshaking signal, 5 - Ground (GND) Common reference voltage, 6 - Data Set Ready (DSR) Incoming handshaking signal, 7 - Request To Send (RTS) Outgoing flow control signal, 8 - Clear To Send (CTS) Incoming flow control signal, 9 - Ring Indicator (RI) Incoming signal from a modem. This connection is different than the connector found at the end of the serial sync cable supplied by HP that connects directly between the iPAQ and a PC.