BeagleBone Black Serial Port

The BeagleBone Black serial port provides low speed +3.3V TTL RS-232 data communication with a wide variety of devices, such as sensors, displays, ADCs, and DACs. There are four serial port UARTs (/dev/ttyO1, /dev/ttyO2, /dev/ttyO4, and /dev/ttyO5), each of which connects to a receiver (RX) and transmitter (TX) pin.

For more information, see:

Do not connect the BeagleBone Black serial port to 12V RS-232 serial ports, which are found on many older computers.