Quatech DSP-200/300 - Manual (Page 47)

6.3 Termination Resistors
No termination resistors are provided on the DSP-200/300 ports. Both output and input signals
are connected only to the external connector. Any termination which is required must be added
externally.
+
-
RS-422/485 Receiver
Rt
RXD+
RXD-
+
-
RS-422/485 Receiver
Rt
AUXIN+
AUXIN-
RS-422
100 ohm 1/2W resistor RS-485
60 ohms total resistance
(120 ohms at each end)
Recommended Termination Resistor Values
Figure 12. RS-422/485 Termination
Hardware Information 6-5