Our friends over at LinkSprite have made this nifty little RS485 Shield, now you will be able to have a communication port for your field bus directly connected to your Arduino! Even though the RS485 is sometimes thought as an "archaic" protocol, it will allow up to 32 devices to communicate through the same data line over a cable length of up to 4000ft with a maximum data rate of 10Mbit/s. Those arent bad numbers!
This shield comes pre-assembled so all you will need to do is just snap it right into your Arduino and get programming.
Note: The shield has an unpopulated footprint for a DB9 connector. Check below if you need to add the connector. Otherwise you can use the screw terminals.