Aaeon SBC-555 Manual page 36

The onboard IR connector supports an Infra-Red port module that
enables wireless commumication between the computer and other
computers and devices with infrared capacity. The port module is
an optional component. If it is installed, you must set the IR
Transfer Mode in the Periphersl section of the CMOS setup
utility.
Pin
4
3
2
1
The HDD LED Connector (CN13) allows user to connect to the
hard disk activity indicator light on the case.
Function
5V
TX
GND
RX