Chapter 1
Motherboard Description
1-26
1.7.3.2 Connectivity
The serial ports can be used in many ways, and it may be necessary to
become familiar with the pinout diagram. The following chart gives you
the function of each pin on the 9-pin connector and some of the 25-pin
connector. This information can be used when configuring certain
software programs to work with the serial ports.
Signal
Name
DB9 PIN
DB25 PIN
DCD
Data Carrier Detect
1
8
RX Receive
Data 2
3
TX Transmit
Data 3
2
DTR
Data Terminal Ready
4
20
GND Signal
Ground
5
7
DSR
Data Set Ready
6
6
RTS
Request to Send
7
4
CTS
Clear to Send
8
5
RI Ring
Indicator 9
22
