Question on Mavlink and Ardupilot on the same Raspberry Pi

[Ian MacIver]

Hi, I am trying to run Python 3 code on a Raspberry Pi with Navio2 ArduPilot and access Mavlink to make calls to the some Ardupilot values. I have the Python code working as expected on another PC (Apple) and also have QGroundControl connecting OK but cannot get it to connect on the Raspberry Pi which is running ArduPilot.

I have the settings in /etc/default/ardupilot as 

TELEM1="-A udp:192.168.178.90:14500"

TELEM2="-A udp:192.168.178.25:14551"

# Options to pass to ArduPilot

ARDUPILOT_OPTS="$TELEM1 $TELEM2"

The address 192.168.178.25 is the Apple Mac running QGC & Python code. When I try and connect with the same python code on the RPi it does not connect, just waits. The working connection code is 

mav = mavutil.mavlink_connection(udp:192.168.178.25:14551')

This connects OK. One bit I do not understand is, why does the python code need to use 192.168.178.25? I would have expected it to point to 192.168.178.90 which the IP address of the RPi running ArduPilot. Which end is the server? 

Does anyone have any idea why I cannot access Mavlink on the RPi? There are no firewall running on the RPI. Thanks 

[Hamish Willee]

The best place to ask this question is https://discuss.ardupilot.org/c/ground-control-software/mavlink/116 , because it is probably an ArduPilot specific rather than MAVLink issue.