Interfacing protocols
USB operation
XBee-PRO 900HP RF Modem User Guide
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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 900HP RF Modem with the RS-485/422 protocol: Twisted pair cabling is
used for the positive and negative data lines. An Ethernet cable is good for twisted pairs.
When using Ethernet twisted pair cabling:
Select wires so that TX+ and TX- are connected to a twisted pair. Likewise, select wires so that RX+
and RX- are connected to a twisted pair. (For example, tie the green and white/green wires to TX+ and
TX). This reduces the amount of noise on the data line.
USB operation
Note that when a Mini-USB cable is plugged into the XBee-PRO 900HP RF Modem, communication to
and from the RS-232 interface and the RS-485/422 is halted. USB communications take precedence
over all other interfaces when you plug it in. To restore communication with other interfaces, the USB
cable should be unplugged.
Note
The Mini-B USB connector is intended as a configuration port. The RF Modem should not
transmit data when the Mini USB cable is connected.
USB pin signals
The following figure shows the pins used on the Type B USB connector:
The following figure shows type B USB connector pin assignments and implementation: