This is a breakout board for the SP3485 RS-485 transceiver IC, which will convert a UART serial stream to RS-485. The SP3485 is a half-duplex transceiver, so it can only communicate one way at a time, but it can reach transmission speeds of up to 10Mbps. This board requires a very low amount of power and can operate from a single +3.3VDC supply.
Resources
Schematic
Eagle Files
Datasheet(SP3485)
GitHub(Design Files)