User manual

UNO-1150 User Manual 12
2.3.5 Terminal Resistor Setup for RS-422/485
The onboard termination resistor (120 Ohm) for COM2/COM3 can be
used for long distance transmission or device matching. (Default Open.)
Each terminal resistor responds to different channels for RS-422/485.
Usually, these resistors are needed for both ends of the communication
wires and the value of the resistors should match the characteristic imped-
ance of the wires used.
Table 2.3: Terminal Resistor Settings
COM port Switch No. Pin Setting Description
COM2 SW4 1 ON 120 Ohm between Data+/
Data- (RS-485)
Or 120 Ohm between Tx+/Tx-
(RS-422)
OFF Open (Default)
2 ON 120 Ohm between Rx+/Rx-
(RS-422)
OFF Open (Default)
COM3 SW1 1 ON 120 Ohm between Data+/
Data- (RS-485)
Or 120 Ohm between Tx+/Tx-
(RS-422)
OFF Open (Default)
2 ON 120 Ohm between Rx+/Rx-
(RS-422)
OFF Open (Default)