Aaeon SBC-357 Manual page 32

You can connect an LED to indicate that an IDE device is in use.
The pin assignments for this jumper are as follows:
Pin Signal
1 -R/W IDE
2 +Vcc
COM2 can also be assigned as RS-422 or RS-485 I/F. Setting
JP2 to assign CN7 (COM2) as RS-422/RS-485 I/F, or otherwise
assign CN7 (COM2) as RS-232 I/F.
RS-232*
2 4 6
1 3 5
RS-422
2 4 6
1 3 5
RS-485
2 4 6
1 3 5
* default
24 SBC-357 User Manual