Rs-232/422/485 Interface (Com1 & Com2); Sw1/Sw2/Sw3 Dip Switch Setting According To Placement - Advantech UNO-3285C User Manual

2.2.1 RS-232/422/485 Interface (COM1 & COM2)
UNO-3285C offers two serial communication interface port.
SW1 for COM1(RS-232/422/485) switch

 SW2 for RS485/422 receiver termination setting
 SW3 for COM2(RS-232/422/485) switch
The COM ports default setting is RS422/485. It can also be switched to RS232 mode
manually.
In RS-422/485 mode, the UNO-3285C automatically detects signals to match RS-
422 or RS-485 networks.
In RS-485 mode, the UNO-3285C automatically detects the direction of incoming
data and switches its transmission direction accordingly. So no handshaking signal
(e.g. RTS signal) is necessary. This lets you conveniently build an RS-485 network
with just two wires. More importantly, application software previously written for half
duplex RS-232 environments can be maintained without modification.
2.2.2

SW1/SW2/SW3 Dip Switch Setting According to Placement

Dip switch definition:
Bit 1: on
Bit 1: off
7 UNO-3285C User Manual