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  • Aug 13 22:16
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Andrew Tridgell
I know that isn't very neat
hmm, actually, you should be able to do it by a lookup on the pymavlink namespace
again using the MAVLINK_MSG_ID_ string
Andrew Tridgell
@guglie this script shows how:
@tridge thanks, I'll try this way!
Atharva Atre
So I have a Raspberry Pi connected to pixhawk and I want to write a python script in Raspi which can start or stop a drone from arming. I was wondering if the community can help me out with some articles or any documentation for the same. Here are the specifications
Raspberry Pi 3 model B
It has APSYNC installed on it
I can SSH into the Raspi with putty
Raspi communicates with pixhawk by rx tx pins
Pierre Kancir
Hello, I advice you to look on ArduPilot autotest how we do it ! You will find the right sequence and check to do. That is in Tools/autotest, in and for example
Atharva Atre
@khancyr Thank you so much ..I will check it out
Juan de Dios Yáñez
Is there a parameter for quadplane within ardupilot that allows to distinguish when its behavior is copter type and when it is plane type?
Berke Yavas

Traceback (most recent call last):
File "src/", line 94, in <module>
File "src/", line 70, in set_servo
0, 0, 0, 0, 0)
File "/Users/berkeyvx/Desktop/Developer/Python/dronekit/venv/lib/python2.7/site-packages/pymavlink/dialects/v10/", line 15559, in command_long_send
return self.send(self.command_long_encode(target_system, target_component, command, confirmation, param1, param2, param3, param4, param5, param6, param7), force_mavlink1=force_mavlink1)
File "/Users/berkeyvx/Desktop/Developer/Python/dronekit/venv/lib/python2.7/site-packages/dronekit/", line 146, in newsendfn
return sendfn(mavmsg, args, *kwargs)
File "/Users/berkeyvx/Desktop/Developer/Python/dronekit/venv/lib/python2.7/site-packages/pymavlink/dialects/v10/", line 11857, in send
buf = mavmsg.pack(self, force_mavlink1=force_mavlink1)
File "/Users/berkeyvx/Desktop/Developer/Python/dronekit/venv/lib/python2.7/site-packages/pymavlink/dialects/v10/", line 8585, in pack
return MAVLink_message.pack(self, mav, 152, struct.pack('<fffffffHBBB', self.param1, self.param2, self.param3, self.param4, self.param5, self.param6, self.param7, self.command, self.target_system, self.target_component, self.confirmation), force_mavlink1=force_mavlink1)
struct.error: required argument is not a float
getting this error

cause of this lines

def set_servo(PWM):
msg = vehicle.message_factory.command_long_send(
0, 0,
mavutil.mavlink.MAV_CMD_DO_SET_SERVO, 0,
'5', PWM,
0, 0, 0, 0, 0)
print vehicle.channels.get('5')

What is wrong

'required argument is not a float' says to me that one of the it's trying to interpret one of your the parameters being passed into 'command_long_send' as a float, and it's not. maybe you should make the PWM value not a float are passing in a PWM value that is 1999.5, and maybe that should be either just 1999 or int(1999.5).
Berke Yavas
i tried that way alsı dont think its the problem but thank you i will try it now
Berke Yavas
I solved, instead of sending command_long_send i used command_long_encode
Berke Yavas

def set_servo(port, PWM, duration):
port -> port where the servo is attached
PWM -> servo ms value, from 1000 - 2000
msg = vehicle.message_factory.command_long_encode(
0, 0,
mavutil.mavlink.MAV_CMD_DO_SET_SERVO, 0,
port, PWM,
0, 0, 0, 0, 0)

while this code had no error, still no changes on channel[port]. Function doesnt work. What is wrong

ignore the duration parameter it has nothing to do with this
Berke Yavas
Drone is in GUIDED mode, should i switch it to AUTO?
Is it possible to create a mission item that is sent to a subcomponent? IE have a mission item that asks a payload component to toggle a relay instead of the autopilot toggling its own relay?
Liang Liu
Hey guys does anyone know why pymavlink is caching telemetry data such as GPS_RAW_INT and HEARTBEAT? Value's arent changing.
Why there is gitignore for ./generator/C/ folder in pymavlink? To push my diploma thesis (adding security into mavlink protocol) little bit, I need to add monocypher library somewhere where all platforms can access it and use it. Thanks
Aren Deutsch
I was wondering if is it possible to set attitude setpoint to pixhawk with pymavlink ?
I’m trying to use the function set_attitude_target_send without any luck. I do not get any error or warning indication from pixhawk.
Im using ardusub with its current stable build.
Ben Boughton

Hi there everyone. I have tried to create simple python script to arm and disarm SITL rover with pymavlink. I can successfully arm, but not able to disarm. I have put it into a Gist available here ( and also posted to the Ardupilot forums (

I've looked at both MavProxy code and Ardupilot autotest and I cannot see anything too different. When I connect to this SITL instance with MavProxy it is able to Arm and Disarm no problems.

Ben Boughton
Figured it out. I'll update my code and forum post shortly :)
I've been trying to read data from a pressure sensor i got : Bar02 thats connected to my Pixhawk 2.4.8 , how do i access what value it's receiving via a python script?
Hello, I've been trying to implement FTP using master.mav.file_transfer_protocol_send(
I am getting an 'ACK' response from cubeblack only for list directory opcode
When I try read file opcode my payload is a list [0, 0, 0, 4, 22, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 115, 101, 108, 102, 95, 112, 117, 98, 107, 101, 121, 46, 112, 101, 109] padded with zeroes
Can someone guide me on how to properly implement this
Kalyan Sriram
hello, how do I explicitly set both the systemid and the componentid of a pymavlink mavlink connection? not target sid/cid, but source (of heartbeat, commands, etc)?
hello! is this the right place to ask about pymavlink in ardusub?
Hello, why I could use the master.mav.distance_sensor_send() but not master.mav.obstacle_distance_send()? Is there any place for adding this to the library?
hey , i mad enable a custom message and i am using pymavlink to receive it. But i do not get that message untill i run or QGCS atleast once . Anyone have any idea how to initialize or stream all the messages?
P.S - i have already tried sending heartbeat "mas.mav.heartbeat_send(mavutil.mavlink.MAV_TYPE_GCS, mavutil.mavlink.MAV_AUTOPILOT_INVALID,0,0,0)" and also used this - "mas.mav.request_data_stream_send(1,1,mavutil.mavlink.MAV_DATA_STREAM_ALL,4,1)".
Please help if anyone has solved this issue
Hello, i try to send the board voltage inside a Mavlink message.
I try BATTERY_STATUS but no luck, what kind of Mavlink message i can send to update the battery voltage used in Mission Planner ?
David Sastre
If I remember correctly the voltage is from system_status or something like that? There is another general status message that sends voltage as well,and at least Qgroundcontrol is what takes for displaying
hi all.. using mavlink command [mavutil.mavlink_connection('udpin:port_num),
wait_heartbeat()] like this we can check the connection, but there is a problem like, won't be receiving an acknowledgement if there is no connection. In programing point this gives trouble by struck in this line when there is connection isssue and waiting for heartbeat. Is there any other API to check the connection instantly connected or not connected. or any other better way to check connection. @Davidsastresas (i hope u can help in this point)
Hello, I need to get the yaw in gazebo simulation with px4 sitl But while using the command master.mav.command_long_send(
master.target_system, master.target_component,
90, 5, 1, 0, 0, 0, 0) am getting result 3 and cant able to get the yaw . can anyone help
Hi, here's a PR to fix mavutil telemetry log writing for UDP ArduPilot/pymavlink#420
Emiliano Alonzo

Hi, I'm working in a UTM ( and I need integrate it with mavlink.

In particular I want to define a new messages, for do that use mavgen as described in

The problem is that I don't know how use the generated py file with pymavlink. Is there a tutorial that shows how to use it?


2 replies
Hi, starting to work with pymavlink. Connection is ok, parameters read/write also. Now I'm stuck on sending a message that is not a parameter (MANUAL_CONTROL for exemple) ; I'm searching for an equivalent of connection.param_set_send for other type of messages, without success. Do I need to consider defining "new message" (and thus to generate the lib) or am I missing something? Thanks
4 replies
Ajay Karthik

Hi, I am noob to programming. I am trying to send custom messages from ardupilot to GCS. I read the documentation from here
i added this to ardupilotmega.xml in ardupilot/modules/mavlink/pymavlink/dialects/v20/

<message id="3001" name="CUSTOM_DATA">
      <description>Drone Data</description>
       <field type="char[50]" name="text">Status text message, without null termination character</field>
      <field type="uint16_t" name="id">Unique (opaque) identifier for this statustext message.  May be used to reassemble a logical long-statustext message from a sequence of chunks.  A value of zero indicates this is the only chunk in the sequence and the message can be emitted immediately.</field>
      <field type="uint8_t" name="chunk_seq">This chunk's sequence number; indexing is from zero.  Any null character in the text field is taken to mean this was the last chunk.</field>

and i reinstalled the updated pymavlink version from ardupilot.
But when I run this code this code I receive this error AttributeError: 'MAVLink' object has no attribute 'custom_data'.
This is the snippet.

from pymavlink import mavutil
import time
from pymavlink.dialects.v20 import ardupilotmega as mavlink2

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

while True:
    txt = "yaaaaaaa"

Any help would be appreciative.

2 replies

Hi, I am trying to get a drone to do an orbit in gazebo simulator using pymavlink code. But pymavlink doesn't have the MAV_CMD_DO_ORBIT message.

Any idea on how to do this ?

Andrew Tridgell
Pymavlink can send any message defined in the xml
2 replies
Hello, I don't quiet see what a Mavlink network should look like (using UDP only). Can I have more than 2 components reliably communicating on same UDP port ? Or do I have to create a new UDP connection each time that two components want to speak to each others ?
How do you debug pymavlink when I am creating listeners in dronekit but im not getting any readings.
However I am connected to the vehicle and I get mavlink messages elsewhere.
@erenaud3 - the key thing to remember when using UDP ( i use it a lot, works well) is that UDP isn't "communicating" as far as its not really two apps talking to each other, it's more like two humans standing in the same room and shouting at each other... when another human shouts into the right target ip/port , it'll be recieved there just as well as the other/s.
it also depends on if you are using multicast (shouting to everyone by design), or target a single ip/port pair, ( only the specific destination and port hears you).
... when a udp packet arrives at mission-planner , it then looks at where that packet came from, and it sends any response back to where the packet just came from. its also smart enough to identify different sysid's and it understands each sysid as a different vehicle, and will keep a separate "where to reply" udp ip/port for each vehicle, so long as they have different sysids.
Randy Mackay
Hi there, more and more discussion is moving to discord so you are all invited to join us over there!
Kapil Rawal

Hello all,

I want to send global_position data from the ground station to pixhawk4 (PS: want to use the prebuilt messages, not custom message) is there a way to do it using telemetry radio. If yes what is the outlined method?

Thank you