7
UNO-1251G User Manual
Chapter 2
H
ardware
F
unctionality
Figure 2.4 Left Panel of UNO-1251G
2.2
Serial Connections
2.2.1
Serial Mode and Terminator Resistor Selection
UNO-1251G provides 3 serial Com ports, COM1 provide RS-485, COM2 provides
RS-422/485 and COM3 provides RS-232. The default setting of COM2 is RS-422.
Users could change COM2 Port serial types to RS-422 or RS-485 by SW7 DIP
switch selection.
The RS-422/485 terminator resistor is default enabled to match impedance. Espe-
cially in fields with electric noise, enabling terminal resistors is helpful to stabilize
communications. Users could change COM2 serial port type and RS-422/485 termi-
nator resistor settings by SW7/Serial Port Setting DIP switch located inside of the
expansion lot on the left side of the UNO- 1251G system. Refer to Appendix A for
their pin assignments and switch setting.