RS-485 (4-wire) and RS-422 Operation
9XTend-PKG-R RS-232/485 RF Modem User Guide
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Wiring diagrams
The following diagram shows the XTend RF Modem in an RS-485 (4-wire) environment.
The following diagram shows the XTend RF Modem in an RS-422 environment.
RS-485/422 connection guidelines
The RS-485/422 protocol provides a solution for wired communications that can tolerate high noise and push signals
over long cable lengths. RS-485/422 signals can communicate as far as 4000 feet (1200 m). RS-232 signals are suitable
for cable distances up to 100 feet (30.5 m).
RS-485 offers multi-drop capability in which up to 32 nodes can be connected. The RS-422 protocol is used for point-
to-point communications.
Suggestions for integrating the XTend RF Modem with the RS-485/422 protocol
1. When using Ethernet twisted pair cabling: Select wires so that T+ and T- are connected to each wire in a twisted
pair. Likewise, select wires so that R+ and R- are connected to a twisted pair. (For example, tie the green and
white/green wires to T+ and T-.)
2. For straight-through Ethernet cable (not cross-over cable) - The following wiring pattern works well: Pin3 to T+,
Pin4 to R+, Pin5 to R-, Pin6 to T-
3. Note that the connecting cable only requires 4 wires (even though there are 8 wires).
4. When using phone cabling (RJ-11) - Pin2 in the cable maps to Pin3 on opposite end of cable and Pin1 maps to Pin4
respectively.