I have observed that Mission planner keeps sending heart-beats to the APM. Can someone please clarify if this is a requirement. I am trying to devlelop an application (with limited functionality) that communicates with APM via MAVProxy. The application would wait passively for messages from the APM, which are relayed by MAVProxy and would respond to certain events (Ex: mode changed to RTL, new waypoint reached etc.). The response can include sending commands to APM. I would like to know if there are any issues with this approach (the application not sending heart-beats to APM, but sending commands occasionally). Thank you.