Digi International’s SX RF modems use 1-Watt industrial-grade 900 MHz long range SX radio technology for wireless cable replacement applications. They are flexible, easy to use and utilize DigiMesh® wireless networking protocol, with redundant mesh network operation and support for low-power sleeping nodes. Available interfaces to the modems include RS-232, RS-485, USB, Analog I/O and Digital I/O.
more info at eeWiki link https://www.eewiki.net/display/Wireless/Xbee+SX+RS232+RS485+RF+Modems
RS232/RS485 SX Xbee modem ; Digi-Key part# 602-1980-ND ;
XBee SX RF Modems User Guide https://www.digi.com/resources/documentation/digidocs/90001517/default.htm
If you have any questions, feel free to post them under this thread.