QDR
– QTech Digital Radio – Owner’s Manual – v1.4 – October 2014
www.qtech.co.nz
Page 9 of 16
5.3 RS485 - Full Duplex Mode
This mode is used for serial data communications where all four signal lines are
required.
Jumper Settings for Full Duplex RS485 (4-Wire)
Refer to Section 6 for further details on the jumpers
Jumper
Position
JP3
In
JP4
In
JP5
Out
JP6
Out
Pinout of RS485 Port when in Full Duplex Mode
Pin
Signal
Input/Output
Description
1
GND
-
Ground
2
B
Input
Inverting Receiver Input
3
A
Input
Non inverting Receiver Input
4
Z
Output
Inverting Driver Output
5
Y
Output
Non inverting Driver Output
6
GND
-
Ground
Typical Full Duplex Connection
Note: Line termination resistors are inside the QDR
120 Ohm
120 Ohm
Y
Z
A
B
Y
A
B
Z
120 Ohm
120 Ohm
