Discussions

Hi all,

I am currently writing a Java code to communicate with a GCS e.g. MP or QGC via UDP. By frequently sending heartbeat messages  my code is able to connect with the GCS and receive some messages from it. However, I am bit confused about the messages I received and I dont know how to response to the GCS.

Here is some message examples received from QCS (decoded):

PARAM_REQUEST_LIST : target_component: 0 ,target_system: 1
HEARTBEAT(sysID-255, componentID-0): autopilot: 8 ,system_status: 4
HEARTBEAT(sysID-255, componentID-0): autopilot: 8 ,system_status: 4
MISSION_REQUEST_LIST : target_component: 190 ,target_system: 1
HEARTBEAT(sysID-255, componentID-0): autopilot: 8 ,system_status: 4
HEARTBEAT(sysID-255, componentID-0): autopilot: 8 ,system_status: 4
MISSION_REQUEST_LIST : target_component: 190 ,target_system: 1
HEARTBEAT(sysID-255, componentID-0): autopilot: 8 ,system_status: 4
HEARTBEAT(sysID-255, componentID-0): autopilot: 8 ,system_status: 4
MISSION_REQUEST_LIST : target_component: 190 ,target_system: 1
HEARTBEAT(sysID-255, componentID-0): autopilot: 8 ,system_status: 4
HEARTBEAT(sysID-255, componentID-0): autopilot: 8 ,system_status: 4
MISSION_REQUEST_LIST : target_component: 190 ,target_system: 1
HEARTBEAT(sysID-255, componentID-0): autopilot: 8 ,system_status: 4
HEARTBEAT(sysID-255, componentID-0): autopilot: 8 ,system_status: 4

MISSION_REQUEST_LIST : target_component: 190 ,target_system: 1
HEARTBEAT(sysID-255, componentID-0): autopilot: 8 ,system_status: 4
HEARTBEAT(sysID-255, componentID-0): autopilot: 8 ,system_status: 4

..

I found this link here which describes the parameter protocol but I do not think I have understood it. In the messages shown above I can see that I have received PARAM_REQUEST_LIST, MISSION_REQUEST_LIST. It also shows REQUEST_DATA_STREAM sometimes. I try to follow the parameter protocol to send MISSION_ITEM (to respond PARAM_REQUEST_LIST) and MISSION_COUNT (to respond MISSION_REQUEST_LIST) but I cannot see whether it works or not. And the following messages received from MP:

..

REQUEST_DATA_STREAM : req_message_rate: 3 ,req_stream_id:6 ,target_component:200 ,start_stop:1
REQUEST_DATA_STREAM : req_message_rate: 3 ,req_stream_id:6 ,target_component:200 ,start_stop:1
REQUEST_DATA_STREAM : req_message_rate: 10 ,req_stream_id:10 ,target_component:200 ,start_stop:1
REQUEST_DATA_STREAM : req_message_rate: 10 ,req_stream_id:10 ,target_component:200 ,start_stop:1
REQUEST_DATA_STREAM : req_message_rate: 10 ,req_stream_id:11 ,target_component:200 ,start_stop:1
REQUEST_DATA_STREAM : req_message_rate: 10 ,req_stream_id:11 ,target_component:200 ,start_stop:1
REQUEST_DATA_STREAM : req_message_rate: 2 ,req_stream_id:12 ,target_component:200 ,start_stop:1
REQUEST_DATA_STREAM : req_message_rate: 2 ,req_stream_id:12 ,target_component:200 ,start_stop:1
REQUEST_DATA_STREAM : req_message_rate: 2 ,req_stream_id:1 ,target_component:200 ,start_stop:1
REQUEST_DATA_STREAM : req_message_rate: 2 ,req_stream_id:1 ,target_component:200 ,start_stop:1
REQUEST_DATA_STREAM : req_message_rate: 2 ,req_stream_id:3 ,target_component:200 ,start_stop:1
REQUEST_DATA_STREAM : req_message_rate: 2 ,req_stream_id:3 ,target_component:200 ,start_stop:1

..

I think I should respond these messages by sending DATA_STREAM but I have no idea what is data stream means here and what is stream_id. Can somebody please explain them?

I tried to send some parameters to GCS and these messages can be inspected, but there is no onboard parameters. I really dont know why.. :s

Thanks!!!

Regards,

Sichao