RS-485 (BOB-10124) Wiring help?


I recently got one of these RS485 breakout boards from Sparkfun with the intention of communicating with a MODBUS device over RS485.

Anyone mind explaining how exactly I wire this up with my Arduino? The BOB seems to have 3 sets of pins, 2 on opposite sides and 1 row (5,3,2,1) on another edge.


The Arduino connects to the left side, from top to down:

Vcc => 3V3 RX-I => pin 0 TX-O => pin 1 RTS => any pin you like (digital IO) GND => GND

The pins on the right are B, A and GND, the connect to the RS485 bus. The bottom pins (marked 5, 3, 2, 1) are the corresponding pins of the RJ-45 connector if you solder on to the breakout.

Thanks very much pylon!