Baller Chica

Hey, I am trying to use the UART pins to talk to an external module. I tried doing this, shorted the RX and TX pins respectively (ttys0-ttys3) screen /dev/ttyS[0-3] 57600 However, I keep getting the message that screen is terminating. uname -a Linux orangepizero 4.10.0-sun8i #14 SMP Fri Feb 24 03:02:58 CET 2017 armv7l armv7l armv7l GNU/Linux Any help is appreciated. UPDATE: Got it working from a solutions from here