Aaeon SBC-670S Manual page 34

This connector provides a 4 pin power outlet to a device such as a
CPU fan.
Pin
1
2
3
4
The SBC-670S offers two RS-232 serial ports, COM1 and COM2,
which let you connect to serial devices (a mouse, a MODEM, etc.)
or a communication network. COM-A is
COM1, and COM-B is COM2.
You can disable each port or select its
address (3F8H [COM1], 2F8H [COM2] or
3E8H) using the AMIBIOS Setup program.
(see Peripheral Setup in Chapter 4)
Different devices implement the RS-232 standard in different
ways. If you get problems, be sure to check the pin assignments
for the connector. The figure above shows the pin assignments
for the card's RS-232 ports:
Function
+5V
GND
GND
+12V
D C D
1
D S R
6
R X
2
R T S
7
T X
3
C T S
8
D T R
4
RI
9
G N D
5