listClients

R2026b

List all connected MAVLink clients

Syntax

clientTable = listClients(mavlink)

Description

clientTable = listClients(mavlink) lists all active connections for the mavlinkio client connection.

Examples

Establish Serial Connection with Pixhawk Board

Connect a local MAVLink client to a serial port and establish communication with a Pixhawk^® 4 board running PX4^® firmware by exchanging heartbeat messages.

Create a mavlinkdialect object using the common.xml file.

dialect = mavlinkdialect("common.xml");

Create a local MAVLink client by using the mavlinkio object.

gcs = mavlinkio(dialect);

Store the remote MAVLink client information by using the mavlinkclient object. This code stores information for a Pixhawk board with a system ID of 1 and a component ID of 1.

uav = mavlinkclient(gcs,1,1)

uav = 
  mavlinkclient with properties:

         SystemID: 1
      ComponentID: 1
    ComponentType: "Unknown"
    AutopilotType: "Unknown"

Connect the local MAVLink client to the same serial port as the Pixhawk board by using the connect function. In this code, the Pixhawk board uses the "COM5" port.

connect(gcs,"Serial",SerialPort="COM5");

Create a heartbeat microservice object.

heartbeat = mavlinkmicroservice(gcs,"heartbeat");

Start sending heartbeat messages to the Pixhawk board by using the start function.

start(heartbeat,uav,"Serial",SerialPort="COM5")

If the Pixhawk board replies with heartbeat messages, the local MAVLink client establishes a connection to it.

Verify that a connection has been established by using the listClients function. Note that the heartbeat messages include the ComponentType and AutopilotType information of the Pixhawk board.

listClients(gcs)

ans = 2×4 table
    SystemID    ComponentID       ComponentType             AutopilotType     
    ________    ___________    ____________________    _______________________

      255            1            "MAV_TYPE_GCS"        "MAV_AUTOPILOT_INVALID"
       1             1         "MAV_TYPE_QUADROTOR"       "MAV_AUTOPILOT_PX4"

Verify that the ComponentType and AutopilotType properties of the mavlinkclient object have been automatically updated to match the heartbeat message values.

uav

uav = 
  mavlinkclient with properties:

         SystemID: 1
      ComponentID: 1
    ComponentType: "MAV_TYPE_QUADROTOR"
    AutopilotType: "MAV_AUTOPILOT_PX4"

To stop the connection, first stop the heartbeat message stream.

stop(heartbeat,uav)

Then, disconnect the local MAVLink client from the serial port.

disconnect(gcs)

Connect Simulated UAV to QGroundControl Through UDP Connection

Connect a local MAVLink client to QGroundControl by exchanging heartbeat messages over UDP,

Open QGroundControl.

Create a mavlinkdialect object using the common.xml file.

dialect = mavlinkdialect("common.xml");

Create a local MAVLink client that represents a simulated UAV by creating a mavlinkio object with these settings:

• MAVLink message definition — dialect

• MAVLink system ID — 1

• MAVLink component ID — 1

• MAVLink component type — MAV_TYPE_QUADROTOR

• MAVLink autopilot type — MAV_AUTOPILOT_GENERIC

uav = mavlinkio(dialect,SystemID=1,ComponentID=1,AutopilotType="MAV_AUTOPILOT_GENERIC", ...
    ComponentType="MAV_TYPE_QUADROTOR");

Store the remote MAVLink client information that represents QGroundControl. By default, QGroundControl has a system ID of 255 and a component ID of 190.

qgc = mavlinkclient(uav,255,190);

Connect the local MAVLink client to a UDP port by using the connect function.

connect(uav,"UDP");

Verify that the local MAVLink client has connected to a UDP port by using the listConnections function.

connectionTable = listConnections(uav)

connectionTable = 
   1x2 table
       ConnectionName         ConnectionInfo     
       ______________      ___________________ 
   
        "Connection1"      "UDP@0.0.0.0:55371"

Create a heartbeat microservice object.

heartbeat = mavlinkmicroservice(uav,"heartbeat");

Specify the host address and port of QGroundControl.

qgcHost = "127.0.0.1";
qgcPort = 14550;

Start sending heartbeat messages to QGroundControl by using the start function.

start(heartbeat,qgc,"UDP",RemoteHost=qgcHost,RemotePort=qgcPort);

If QGroundControl replies with heartbeat messages, the local MAVLink client establishes a connection to it.

Verify that the connection has been established by using the listClients function.

listClients(uav)

ans = 2×4 table
    SystemID    ComponentID       ComponentType             AutopilotType     
    ________    ___________    ____________________    _______________________

      255           190          "MAV_TYPE_GCS"        "MAV_AUTOPILOT_INVALID"
       1             1        "MAV_TYPE_QUADROTOR"     "MAV_AUTOPILOT_GENERIC"

To stop the connection, first stop the heartbeat message stream.

stop(heartbeat,gcs)

Then, disconnect the local MAVLink client from the UDP port.

disconnect(uav)

Input Arguments

mavlink — Local MAVLink client

mavlinkio object

Local MAVLink client, specified as a mavlinkio object.

Output Arguments

clientTable — Active client info

table

Active connection info, returned as a table with SystemID, ComponentID, ConnectionType, and AutopilotType fields for each active client.

Version History

Introduced in R2019a