Avalue EEV-EX20 - Manual (Page 15)

Quick Installation Guide
EEV-EX20 Quick Installation Guide 15
2.3.6 Serial port 2 in RS-422/485 mode (JRS422/485)
In 422 mode
Signal PIN PIN Signal
TX- 1 2 RX-
TX+ 3 4 RX+
+5V 5 6 GND
In 485 mode
Signal PIN PIN Signal
DATA- 1 2 NC
DATA+ 3 4 NC
+5V 5 6 GND
2.3.7 Audio Codec select (JP3)
* Default
Module Audio Codec*
Carrier Audio Codec