Cant connect to PX4

`` root@odroid:~# mavproxy.py --master=/dev/ttyUSB0 --baudrate 1500000 --aircraft MyCopter
Connect /dev/ttyUSB0 source_system=255
Running script MyCopter/mavinit.scr
-> set moddebug 2
-> module load graph
Loaded module graph
Log Directory: MyCopter/logs/2016-11-06/flight17
Telemetry log: MyCopter/logs/2016-11-06/flight17/flight.tlog
MAV> Waiting for heartbeat from /dev/ttyUSB0
online system 1
STABILIZE> Mode STABILIZE
arm
STABILIZE> usage: arm
arm throttle
STABILIZE> root@odroid:~# ``

> I want to connect mavproxy to px4, but it still not work. the mavproxy only listen from px4 but I cant input command to px4. How to fix it? please help

Start by reproducing the issue with the recorded mavproxy.py command and terminal output, then inspect how MAVProxy handles PX4 heartbeat and command input. Done means commands sent through the CLI are accepted by PX4, with the failure and resolution covered by a regression test or documented reproduction.

Written by the indexing model from the issue text.