Advantech ECU-4674 Series User Manual page 21

4. COM1-10 RS-485/RS-232 terminal resistance setup instructions.
CN12, CN14,
CN16, CN18,
CN20, CN22,
CN24, CN26,
CN28, CN31
COM Port Jumper for Terminal Resistor
COM1 CN28
COM2 CN31
COM3 CN16
COM4 CN18
COM5 CN20
COM6 CN22
COM7 CN24
COM8 CN26
COM9 CN12
COM10 CN14
5. COM1-COM10 Switch setting of RS-422 Master/Slave Selection.
SW2 OFF (default)
ON
Add 120 ohm terminal resistor on TX+/TX- of RS-485
Add 300 ohm terminal resistor on TX+/TX- of RS-485
Add 120 ohm terminal resistor on RX+/RX- of RS-422 (optional)
Add 300 ohm terminal resistor on Rx+/RX- of RS-422 (optional)
RS-422 Slave mode
RS-422 Master mode
13 ECU-4674 User Manual