Request message HOME_POSITION works only one time per connection, and few other questions

[savend]

Hi,
I'm beginning working with mavlink and pymavlink librairies and I think I'm missing some important details to understand all. For debbuging I'm using the mission planner quadcopter stable SITL.
My first problem is that I can only ask for the HOME_POSITION message one time per connection : here is the terminal results :

Python 3.11.2 (tags/v3.11.2:878ead1, Feb  7 2023, 16:38:35) [MSC v.1934 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> from pymavlink import mavutil
>>> from pymavlink import mavwp
>>> connection = mavutil.mavlink_connection('tcp:localhost:5762')
>>> connection.wait_heartbeat()
<pymavlink.dialects.v20.ardupilotmega.MAVLink_heartbeat_message object at 0x0000022A931CBE50>
>>> print("Heartbeat from system (system %u component %u)" % (connection.target_system, connection.target_component))
Heartbeat from system (system 1 component 0)
>>> connection.mav.command_long_send(1,0, mavutil.mavlink.MAV_CMD_REQUEST_MESSAGE, 0, 242, 0, 0, 0, 0, 0,0)
>>>
>>> print(connection.recv_match("HOME_POSITION", blocking=True))
HOME_POSITION {latitude : -[353633515](tel:353633515), longitude : 1491652412, altitude : 585050, x : 0.0, y : 0.0, z : 0.0, q : [1.0, 0.0, 0.0, 0.0], approach_x : 0.0, approach_y : 0.0, approach_z : 0.0, time_usec : [818545784](tel:818545784)}
>>> connection.mav.command_long_send(1,0, mavutil.mavlink.MAV_CMD_REQUEST_MESSAGE, 0, 242, 0, 0, 0, 0, 0,0)
>>>
>>> print(connection.recv_match("HOME_POSITION", blocking=True))
HEARTBEAT {type : 2, autopilot : 3, base_mode : 81, custom_mode : 0, system_status : 3, mavlink_version : 3}
>>>

If I restart python terminal (break the mavlink connection) I can ask again the HOME_POSITION without restarting the SITL.

Few other questions :

• Where are the mav.command_long_send() or connection.amv.send() functions defined in pymavlink? To understand what they doing I tried to find the source code, but I didn't find it. (Same for all the enums, messages and commands numbers)
• How can I disconnect a mavlink connection properly?

I'm trying to answer most of my question with the rare examples and documentation, but need some additional explanations! Thanks for that.

[jnippula]

Those xx_send functions are generated, can be found from pymavlink/generator//<mav_version//mavlink_msg_.h files after running generator.