Pixracer + companion mavlink connexion

Hi,
I try to make mavlink connexion between Pixracer and raspberry or odroid U3. I have QGC last version + Copter 3,4,4 on the pixracer.

It’s connect with an serial to usb cable.
So I try on Telem2 to see if it’s work. Yes, I can connect (SSH on mac) it but I get for example on Odroid U3 but same with Paspberry:

tiny@odroid-jessie:~$ mavproxy.py --master=/dev/ttyUSB0 --baudrate=57600
Connect /dev/ttyUSB0 source_system=255
Log Directory:
Telemetry log: mav.tlog
MAV> Waiting for heartbeat from /dev/ttyUSB0
online system 1
STABILIZE> Mode STABILIZE
APM: APM:Copter V3.4.4 (8a196281)
APM: PX4: de6b667d NuttX: 8c965992
APM: Frame: QUAD
APM: PX4v4 002C003D 33355108 34383732
Mode(0x00000000)> STABILIZE> Mode(0x00000000)> STABILIZE> Mode(0x00000000)> Mode Mode(0x00000000)
STABILIZE> Mode(0x00000000)> STABILIZE> Mode(0x00000000)> STABILIZE> Mode STABILIZE
Mode(0x00000000)> STABILIZE> Mode(0x00000000)> STABILIZE> Mode(0x00000000)> Mode Mode(0x00000000)
STABILIZE> Mode(0x00000000)> STABILIZE> Mode(0x00000000)> STABILIZE> Mode STABILIZE
Mode(0x00000000)> STABILIZE> Mode(0x00000000)> Received 593 parameters
Saved 593 parameters to mav.parm
fence breach
STABILIZE> Mode(0x00000000)> Mode Mode(0x00000000)
STABILIZE> Mode(0x00000000)> STABILIZE>
And data not stopping with Mode(0x000000000)

I try to fix CTS/RTS signal on QGC board parameter but nothing better

So is there something I miss about because it’s not really complicate and should work as it did working on a Pixhawk couple years ago.
Thanks a lot if you can help to fix that