ADLINK cPCI-3620 - Manual (Page 48)

36 Board Interfaces
cPCI-3620T COM1 Mode Selection Switch (SW1)
These switches set the cPCI-3620T COM1 to RS-232 full
modem, RS-422 or RS-485. Switch SW1 is located next to the
COM1 connector on the DB-3620L2 board. RS-232 full modem
is set by default.
Mode Pin SW1
RS-232
1 ON
2 OFF
RS-422
1 ON
2 ON
RS-485
1 OFF
2 ON
SW1