Using RS-485 Converters with Digi Interface Boards

Digi's XTend, 900 HP and XBee PRO SX serial interface radio modems are configurable using DIP switch settings to as well as AT commands to select either RS-232 or RS-485 configurations, eliminating the need for an RS-232 to RS-485 converter. However, customers may find it necessary to connect an RS-232 host (PC, PLC, etc.) to an RS-485 connection to the radio. Testing or extension of the serial cable link may be possible in this way. For example, in cases where the radios will be installed on towers or building rooftops, it is recommended to use a longer serial cable to reduce the amount of antenna cable attenuation. RS-232 serial cable may not be feasible for these distances. However, RS-485 cable can be as long as 4000 feet. An inexpensive hardwired RS-485 to RS-232 converter can be found with an internet search.

Custom CAT5 cables can be engineered using Digi's DB9 to RJ45 modular jacks. CAT5 cable is ideal for integration and cost effective for running long distances.

During installation, make sure the DIP switches on both the converter and the interface board are set according to desired specification. Be sure to read the Product Manuals for the Associated radio as well to ensure that you are making the proper configuration changes. 

Below is a quick electrical pin reference for integration:

RS-485 4WR

RS-485 2WR

B&B Digi PKG B&B Digi PKG
         2 (R+) 2 (T-)          2 (T/R-) 2 (T/R-)
         3 (T+) 7 (R+)          3 (T/R+) 8 (T/R+)
         4 (G)* 5 (G)*          4 (G)* 5 (G)*
         7 (R-) 8 (T+) DC Voltage Supply* 9 (VCC)*
         8 (T-) 3 (R-)    
DC Voltage Supply* 9 (VCC)*    


Last updated: Mar 11, 2024

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RFRF Dev kits

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