Here is detailed Logic Supply tutorial on how to enable the BeagleBone Black to communicate over an RS-485 bus.
The RS-485 standard defines a serial communication protocol that uses differential signalling over a twisted pair of wires as a shared bus to create local networks of up to 32 devices. The natural noise immunity of differential twisted pairs makes RS-485 well suited for spanning much greater physical lengths than other serial protocols like RS-232.
The BeagleBone isn’t capable of generating the differential signals required by RS-485, but there are many RS-485 transceiver ICs available that can convert between RS-485 and TTL serial levels, enabling the BeagleBone to communicate over an RS-485 bus using its built-in UARTs. This example will show how to do so with the Logic Supply serial cape, using its on-board Zywyn ZT3485 half-duplex RS-485 transceiver connected to UART4.
Each Tuesday is BeagleBone Black Day here Adafruit! What is the BeagleBone? The BeagleBones are a line of affordable single-board Linux computers (SBCs) created by Texas Instruments. New to the Bone? Grab one of our Adafruit BeagleBone Black Starter Packs and check out our extensive resources available on the Adafruit Learning System including a guide to setting up the Adafruit BeagleBone IO Python Library. We have a number of Bone accessories including add-on shields (called “capes”) and USB devices to help you do even more with your SBC. Need a nice display to go along with your Bone? Check out our fine selection of HDMI displays, we’ve tested all of them with the Beagle Bone Black!