Command not supprted

Blue Robotics Software
1

Hi,

I am trying to launch an order via mavlink and MAV_CMD_REQUEST_MESSAGE
My code:

from pymavlink import mavutil
master = mavutil.mavlink_connection(self.url)
master.wait_heartbeat()

master.mav.command_long(master.target_system, master.target_component,
mavutil.mavlink.MAV_CMD_REQUEST_MESSAGE,
0, 74, 0, 0, 0, 0, 0, 0, 0)

ack = False
while not ack:
ack_msg = master.recv_match(type=‘COMMAND_ACK’, blocking=True)
ack_msg = ack_msg.to_dict()
print(mavutil.mavlink.enums[‘MAV_RESULT’][ack_msg[‘result’]].description)

But I have an error message:

AttributeError: ‘MAVLink’ object has no attribute ‘command_long’

If I replace command_long with command_long_send in my code, I’ve the message :

Command is not supported (unknown)

What’s the problem?

Thanks,

Nico

2

Hi,

Please take a look in our pymavlink documentation, about the error message while using command_long_send, please display the full output.

3

Here is my complete script
ROVPilot2.txt (1.8 KB)

And here is the output:
image

Nico

4

Hi,

I just did a simple test and the code works here:

from pymavlink import mavutil                                                                                                                                                                                        
master = mavutil.mavlink_connection('udpin:0.0.0.0:14550')
master.wait_heartbeat()

master.mav.command_long_send(master.target_system, master.target_component, mavutil.mavlink.MAV_CMD_REQUEST_MESSAGE, 0, 74, 0, 0, 0, 0, 0, 0, 0)

ack = False
while not ack:
    ack_msg = master.recv_match(type='COMMAND_ACK', blocking=True)
    ack_msg = ack_msg.to_dict()
    print(mavutil.mavlink.enums['MAV_RESULT'][ack_msg['result']].description)

From the code that you shared, it appears that you have not shared the entire script, please test this minimum example or share a complete file with the minimum amount of code to replicate your issue.

5

I ran your code (ROVPilot2b.txt (657 Bytes) ), and I still get the same error message:

Command is not supported (unknown)

My version of pymavlink is 2.4.8
My version of ArduSub is 3.5.4

Nico

6

I updated the pixhawk firmware (new version 4.0.1) and now I have a message:

image

So the command is OK, but how do I display the result? (in my example, I made a request on message 74 (VFR_HUD) to retrieve the depth)

Nico

7

Hi @AWDRONE,

So you should change the recv_match argument from COMMAND_ACK to VFR_HUD, or check if the message was received, check Receive data and filter by message type in our python examples.

8

Hi,

Thanks, it works.
I can recover the battery voltage with the SYS_STATUS parameter, the depth with the VFR_HUD parameter.
I would also like to recover the tilt of the camera, and the power of the headlights, but I don’t see what parameter to check.

Nico

9

Check the SERVO_OUTPUT_RAW message, where each port will be the servo output ports of your pixhawk.

If you only needs to fetch values, I would recommend to take a look in our new mavlink rest API.

10

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