Sending custom MAVLink commands in Drone Programming - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this MAVLink command send code?

Consider this Python snippet using pymavlink to send a custom MAVLink command to a drone. What will be printed?

Drone Programming

from pymavlink import mavutil

master = mavutil.mavlink_connection('udpout:localhost:14550')

master.target_system = 1
master.target_component = 1

# Send a command_long message with command ID 3000 and parameters 1,2,3,4,5,6
master.mav.command_long_send(
    master.target_system,
    master.target_component,
    3000,  # custom command ID
    0,     # confirmation
    1, 2, 3, 4, 5, 6, 0
)

print('Command sent with ID 3000 and params 1-6')

A Command sent with ID 3000 and params 1-6

B SyntaxError: missing parentheses in call to 'print'

C TypeError: command_long_send() missing 1 required positional argument

D RuntimeError: connection not established

💡 Hint

Check the print statement and the parameters passed to command_long_send.

The code correctly sends a custom MAVLink command with ID 3000 and prints the confirmation message. No errors occur.

🧠 Conceptual

intermediate

Which parameter in command_long_send specifies the target system?

In the command_long_send function of pymavlink, which argument represents the target system ID?

A The second argument

B The fourth argument

C The third argument

D The first argument

💡 Hint

Look at the function signature: command_long_send(target_system, target_component, command, confirmation, param1, ...)

The first argument to command_long_send is target_system, which specifies the system ID of the drone to receive the command.

🔧 Debug

advanced

Why does this custom MAVLink command fail to send?

Review this code snippet that attempts to send a custom MAVLink command but fails. What is the likely cause?

Drone Programming

from pymavlink import mavutil

master = mavutil.mavlink_connection('udpout:localhost:14550')

# Missing target_system and target_component arguments
master.mav.command_long_send(
    3000,  # command ID
    0,     # confirmation
    1, 2, 3, 4, 5, 6, 0
)

print('Command sent')

A The connection string 'udpout:localhost:14550' is incorrect

B The command ID 3000 is invalid and causes failure

C The command_long_send call is missing required target_system and target_component arguments

D The print statement causes a runtime error

💡 Hint

Check the function signature and the number of arguments passed.

The command_long_send method requires target_system and target_component as the first two arguments. Omitting them causes the command not to send.

📝 Syntax

advanced

Which option correctly sends a custom MAVLink command with parameters?

Choose the correct Python code snippet that sends a custom MAVLink command with ID 4000 and parameters 10, 20, 30.

A master.mav.command_long_send(4000, 0, 10, 20, 30, 0, 0, 0)

B master.mav.command_long_send(master.target_system, master.target_component, 4000, 0, 10, 20, 30, 0, 0, 0, 0)

C master.mav.command_long_send(master.target_system, 4000, master.target_component, 0, 10, 20, 30, 0, 0, 0)

D master.mav.command_long_send(master.target_component, master.target_system, 4000, 0, 10, 20, 30, 0, 0, 0)

💡 Hint

Remember the order of arguments: target_system, target_component, command, confirmation, params...

Option B correctly follows the argument order for command_long_send. Other options mix argument order or omit required arguments.

🚀 Application

expert

How many parameters can you send in a single custom MAVLink command_long message?

The command_long_send method allows sending parameters with the command. How many parameters can you include in one command?

A 7 parameters

B 8 parameters

C 6 parameters

D 10 parameters

💡 Hint

Check the MAVLink COMMAND_LONG message definition.

The COMMAND_LONG message supports exactly 7 parameters: param1 through param7.