Aaeon PCM-4894 User Manual page 35

You can set the RI function mode of COM3/4 via JP1. The
available configurations are as follows:
2 4
*
1 3
1-2* COM3 RI = RI function
3-4 COM3 RI = +5V output
5-6 COM3 RI = +12V output
7-8* COM4 RI = RI function
9-10 COM4 RI = +5V output
11-12 COM4 RI = +12V output
* default
6 8 10 12
*
5 7 9 11
Chapter 2 Installation 29