ArduPilot · tridge · Jul 27, 2026 · Jul 27, 2026 · Jul 27, 2026 · Jul 27, 2026
diff --git a/AntennaTracker/GCS_MAVLink_Tracker.cpp b/AntennaTracker/GCS_MAVLink_Tracker.cpp
@@ -254,7 +254,7 @@ void GCS_MAVLINK_Tracker::packetReceived(const mavlink_status_t &status,
                                          const mavlink_message_t &msg)
 {
     // return immediately if sysid doesn't match our target sysid
-    if ((tracker.g.sysid_target != 0) && (tracker.g.sysid_target != msg.sysid)) {
+    if ((tracker.g.sysid_target != 0) && (uint32_t(tracker.g.sysid_target.get()) != msg.sysid)) {
         GCS_MAVLINK::packetReceived(status, msg);
         return;
     }

diff --git a/AntennaTracker/GCS_Tracker.cpp b/AntennaTracker/GCS_Tracker.cpp
@@ -1,7 +1,7 @@
 #include "GCS_Tracker.h"
 #include "Tracker.h"
 
-void GCS_Tracker::request_datastream_position(const uint8_t _sysid, const uint8_t compid)
+void GCS_Tracker::request_datastream_position(const uint32_t _sysid, const uint8_t compid)
 {
     for (uint8_t i=0; i < num_gcs(); i++) {
             // request position
@@ -17,7 +17,7 @@ void GCS_Tracker::request_datastream_position(const uint8_t _sysid, const uint8_
     }
 }
 
-void GCS_Tracker::request_datastream_airpressure(const uint8_t _sysid, const uint8_t compid)
+void GCS_Tracker::request_datastream_airpressure(const uint32_t _sysid, const uint8_t compid)
 {
     for (uint8_t i=0; i < num_gcs(); i++) {
             // request air pressure

diff --git a/AntennaTracker/GCS_Tracker.h b/AntennaTracker/GCS_Tracker.h
@@ -30,7 +30,7 @@ class GCS_Tracker : public GCS
 
 private:
 
-    void request_datastream_position(uint8_t sysid, uint8_t compid);
-    void request_datastream_airpressure(uint8_t sysid, uint8_t compid);
+    void request_datastream_position(uint32_t sysid, uint8_t compid);
+    void request_datastream_airpressure(uint32_t sysid, uint8_t compid);
 
 };
diff --git a/AntennaTracker/Parameters.cpp b/AntennaTracker/Parameters.cpp
@@ -19,7 +19,7 @@ const AP_Param::Info Tracker::var_info[] = {
     // @Param: SYSID_TARGET
     // @DisplayName: Target vehicle's MAVLink system ID
     // @Description: The identifier of the vehicle being tracked. This should be zero (to auto detect) or be the same as the MAV_SYSID parameter of the vehicle being tracked.
-    // @Range: 1 255
+    // @Range: 1 16777215
     // @User: Advanced
     GSCALAR(sysid_target,           "SYSID_TARGET",    0),
 

diff --git a/AntennaTracker/Parameters.h b/AntennaTracker/Parameters.h
@@ -140,7 +140,7 @@ class Parameters {
 
     // Telemetry control
     //
-    AP_Int16 sysid_target;
+    AP_Int32 sysid_target;
 
     AP_Float yaw_slew_time;
     AP_Float pitch_slew_time;

diff --git a/AntennaTracker/system.cpp b/AntennaTracker/system.cpp
@@ -5,6 +5,9 @@ static const StorageAccess wp_storage(StorageManager::StorageMission);
 
 void Tracker::init_ardupilot()
 {
+    // PARAMETER_CONVERSION - Added: Jul-2026 for 32 bit sysids
+    g.sysid_target.convert_parameter_width(AP_PARAM_INT16);
+
     // initialise notify
     notify.init();
     AP_Notify::flags.pre_arm_check = true;

diff --git a/ArduCopter/Parameters.cpp b/ArduCopter/Parameters.cpp
@@ -1337,6 +1337,11 @@ void Copter::load_parameters(void)
     copter.avoid.convert_params();
 #endif
 
+#if MODE_FOLLOW_ENABLED
+    // convert Follow parameters
+    copter.g2.follow.convert_params();
+#endif
+
     // convert PILOT vertical speed and acceleration parameters
     // PARAMETER_CONVERSION - Added: Feb 2026 for ardupilot-4.7
     {

diff --git a/ArduPlane/GCS_MAVLink_Plane.cpp b/ArduPlane/GCS_MAVLink_Plane.cpp
@@ -746,13 +746,15 @@ MAV_RESULT GCS_MAVLINK_Plane::handle_command_int_packet(const mavlink_command_in
 #endif
 
 #if AP_SCRIPTING_ENABLED && AP_FOLLOW_ENABLED
-    case MAV_CMD_DO_FOLLOW:
+    case MAV_CMD_DO_FOLLOW: {
         // param1: sysid of target to follow
-        if ((packet.param1 > 0) && (packet.param1 <= 255)) {
-            plane.g2.follow.set_target_sysid((uint8_t)packet.param1);
+        const int64_t sysid = (int64_t)packet.param1;
+        if (sysid > 0 && sysid <= (int64_t)0xFFFFFFFF) {
+            plane.g2.follow.set_target_sysid((uint32_t)sysid);
             return MAV_RESULT_ACCEPTED;
         }
         return MAV_RESULT_DENIED;
+    }
 #endif
 
 #if AP_ICENGINE_ENABLED

diff --git a/ArduPlane/Parameters.cpp b/ArduPlane/Parameters.cpp
@@ -1478,6 +1478,11 @@ void Plane::load_parameters(void)
 
     g.use_reverse_thrust.convert_parameter_width(AP_PARAM_INT16);
 
+#if AP_SCRIPTING_ENABLED && AP_FOLLOW_ENABLED
+    // convert Follow parameters
+    g2.follow.convert_params();
+#endif
+
     // PARAMETER_CONVERSION - Added: Jun-2026 for FBWB_CLIMB_RATE width change
     g.flybywire_climb_rate.convert_parameter_width(AP_PARAM_INT8);
 

diff --git a/Rover/Parameters.cpp b/Rover/Parameters.cpp
@@ -842,6 +842,11 @@ void Rover::load_parameters(void)
     };
     AP_Param::convert_old_parameters(&ff_and_filt_conversion_info[0], ARRAY_SIZE(ff_and_filt_conversion_info));
 
+#if AP_FOLLOW_ENABLED
+    // convert Follow parameters
+    g2.follow.convert_params();
+#endif
+
     // configure safety switch to allow stopping the motors while armed
 #if HAL_HAVE_SAFETY_SWITCH
     AP_Param::set_default_by_name("BRD_SAFETYOPTION", AP_BoardConfig::BOARD_SAFETY_OPTION_BUTTON_ACTIVE_SAFETY_OFF|

diff --git a/Rover/mode_auto.cpp b/Rover/mode_auto.cpp
@@ -497,7 +497,7 @@ void ModeAuto::send_guided_position_target()
         guided_target.last_sent_ms = now_ms;
 
         // get system id and component id of offboard navigation system
-        uint8_t sysid;
+        uint32_t sysid;
         uint8_t compid;
         mavlink_channel_t chan;
         if (GCS_MAVLINK::find_by_mavtype(MAV_TYPE_ONBOARD_CONTROLLER, sysid, compid, chan)) {

diff --git a/Tools/AP_Periph/adsb.cpp b/Tools/AP_Periph/adsb.cpp
@@ -86,7 +86,11 @@ void AP_Periph_FW::adsb_update(void)
                                                        &adsb.status,
                                                        &msg, &heartbeat);
 
-        uart->write((uint8_t*)&msg.magic, len);
+        uint8_t msgbuf[len];
+        len = mavlink_msg_to_send_buffer(msgbuf, &msg);
+        if (len > 0) {
+            uart->write(msgbuf, len);
+        }
     }
 }
 

diff --git a/Tools/autotest/rover.py b/Tools/autotest/rover.py
@@ -6663,6 +6663,70 @@ def TestWebServer(self, url):
 
         self.progress("WebServer tests OK")
 
+    def MAV_SYSID_32bit(self):
+        '''test 32 bit MAV_SYSID'''
+        if not hasattr(mavutil.mavlink, "MAVLINK_IFLAG_SYSID32"):
+            raise NotAchievedException("pymavlink is too old for 32 bit system IDs")
+
+        # sysid values must round-trip losslessly through the float32
+        # parameter transport, so stay below 2^24 for now
+        sysid = 100000
+        self.set_parameter("MAV_SYSID", sysid)
+
+        # the sysid changes across the reboot so we can't use
+        # reboot_sitl(); send the reboot at the old sysid and re-point
+        # the connection at the new one
+        self.send_reboot_command()
+        self.mav.target_system = sysid
+        self.sysid_thismav = lambda: sysid
+        try:
+            self.wait_heartbeat(timeout=60)
+            m = self.wait_heartbeat()
+            if m.get_srcSystem() != sysid:
+                raise NotAchievedException("Did not get 32 bit sysid, got %u" % m.get_srcSystem())
+            hdr = m.get_header()
+            if not (hdr.incompat_flags & mavutil.mavlink.MAVLINK_IFLAG_SYSID32):
+                raise NotAchievedException("expected MAVLINK_IFLAG_SYSID32 to be set")
+
+            # parameter fetch at the new sysid
+            if int(self.get_parameter("MAV_SYSID")) != sysid:
+                raise NotAchievedException("MAV_SYSID readback failed")
+
+            # our own GCS with a 32 bit source system, and a targeted
+            # message each way
+            mav2 = mavutil.mavlink_connection(
+                "tcp:localhost:%u" % self.adjust_ardupilot_port(5763),
+                robust_parsing=True,
+                source_system=70000,
+                source_component=7,
+            )
+            mav2.mav.param_request_read_send(sysid, 1, b"MAV_SYSID", -1)
+            m = mav2.recv_match(type='PARAM_VALUE', blocking=True, timeout=10)
+            if m is None:
+                raise NotAchievedException("no PARAM_VALUE for 32 bit source system")
+            if m.param_id != "MAV_SYSID" or int(m.param_value) != sysid:
+                raise NotAchievedException("bad PARAM_VALUE %s" % str(m))
+            mav2.close()
+
+            # targeted mission-protocol round trip (the mission upload
+            # helpers hard-code target system 1, so do this by hand)
+            self.mav.mav.mission_request_list_send(sysid, 1, mavutil.mavlink.MAV_MISSION_TYPE_MISSION)
+            m = self.assert_receive_message('MISSION_COUNT', timeout=10)
+            if m.mission_type != mavutil.mavlink.MAV_MISSION_TYPE_MISSION:
+                raise NotAchievedException("bad MISSION_COUNT")
+
+            self.wait_ready_to_arm()
+            self.arm_vehicle()
+            self.disarm_vehicle()
+        finally:
+            # restore the old sysid
+            self.set_parameter("MAV_SYSID", 1)
+            self.send_reboot_command()
+            del self.sysid_thismav
+            self.mav.target_system = 1
+            self.wait_heartbeat(timeout=60)
+            self.wait_heartbeat()
+
     def NetworkingWebServer(self):
         '''web server'''
         applet_script = "net_webserver.lua"
@@ -7553,6 +7617,7 @@ def tests(self):
             self.MAV_CMD_BATTERY_RESET,
             self.GPSForYaw,
             self.NetworkingWebServer,
+            self.MAV_SYSID_32bit,
             self.NetworkingWebServerPPP,
             self.RTL_SPEED,
             self.ScriptingLocationBindings,

diff --git a/libraries/AP_AccelCal/AP_AccelCal.cpp b/libraries/AP_AccelCal/AP_AccelCal.cpp
@@ -183,7 +183,7 @@ void AP_AccelCal::update()
     }
 }
 
-void AP_AccelCal::start(GCS_MAVLINK *gcs, uint8_t sysid, uint8_t compid)
+void AP_AccelCal::start(GCS_MAVLINK *gcs, uint32_t sysid, uint8_t compid)
 {
     if (gcs == nullptr || _started) {
         return;
@@ -364,7 +364,7 @@ bool AP_AccelCal::client_active(uint8_t client_num)
 }
 
 #if HAL_GCS_ENABLED
-void AP_AccelCal::handle_command_ack(const mavlink_command_ack_t &packet, uint8_t src_sysid, uint8_t src_compid)
+void AP_AccelCal::handle_command_ack(const mavlink_command_ack_t &packet, uint32_t src_sysid, uint8_t src_compid)
 {
     if(_sysid != src_sysid || _compid != src_compid) {
         return;

diff --git a/libraries/AP_AccelCal/AP_AccelCal.h b/libraries/AP_AccelCal/AP_AccelCal.h
@@ -28,7 +28,7 @@ class AP_AccelCal {
     { update_status(); }
 
     // start all the registered calibrations
-    void start(GCS_MAVLINK *gcs, uint8_t sysid, uint8_t compid);
+    void start(GCS_MAVLINK *gcs, uint32_t sysid, uint8_t compid);
 
     // called on calibration cancellation
     void cancel();
@@ -46,15 +46,15 @@ class AP_AccelCal {
     static void register_client(AP_AccelCal_Client* client);
 
 #if HAL_GCS_ENABLED
-    void handle_command_ack(const mavlink_command_ack_t &packet, uint8_t src_sysid, uint8_t src_compid);
+    void handle_command_ack(const mavlink_command_ack_t &packet, uint32_t src_sysid, uint8_t src_compid);
 #endif
 
     // true if we are in a calibration process
     bool running(void) const;
 
 private:
     class GCS_MAVLINK *_gcs;
-    uint8_t _sysid;
+    uint32_t _sysid;
     uint8_t _compid;
     bool _use_gcs_snoop;
     bool _waiting_for_mavlink_ack = false;

diff --git a/libraries/AP_BattMonitor/AP_BattMonitor.cpp b/libraries/AP_BattMonitor/AP_BattMonitor.cpp
@@ -1148,7 +1148,7 @@ void AP_BattMonitor::checkPoweringOff(void)
             cmd_msg.command = MAV_CMD_POWER_OFF_INITIATED;
             cmd_msg.param1 = i+1;
             GCS_MAVLINK::send_to_components(MAVLINK_MSG_ID_COMMAND_LONG, (char*)&cmd_msg, sizeof(cmd_msg));
-            GCS_SEND_TEXT(MAV_SEVERITY_WARNING, "Vehicle %d battery %d is powering off", mavlink_system.sysid, i+1);
+            GCS_SEND_TEXT(MAV_SEVERITY_WARNING, "Vehicle %u battery %d is powering off", (unsigned)mavlink_system.sysid, i+1);
 #endif
 
             // only send this once

diff --git a/libraries/AP_CANManager/AP_MAVLinkCAN.cpp b/libraries/AP_CANManager/AP_MAVLinkCAN.cpp
@@ -295,7 +295,7 @@ void AP_MAVLinkCAN::_handle_can_filter_modify(const mavlink_message_t &msg)
 void AP_MAVLinkCAN::can_frame_callback(uint8_t bus, const AP_HAL::CANFrame &frame, AP_HAL::CANIface::CanIOFlags flags)
 {
     mavlink_channel_t chan;
-    uint8_t system_id;
+    uint32_t system_id;
     uint8_t component_id;
     {
         WITH_SEMAPHORE(can_forward.sem);

diff --git a/libraries/AP_CANManager/AP_MAVLinkCAN.h b/libraries/AP_CANManager/AP_MAVLinkCAN.h
@@ -48,7 +48,7 @@ class AP_MAVLinkCAN {
      */
     struct {
         mavlink_channel_t chan;
-        uint8_t system_id;
+        uint32_t system_id;
         uint8_t component_id;
         uint8_t frame_counter;
         uint32_t last_callback_enable_ms;

diff --git a/libraries/AP_Camera/AP_Camera_MAVLinkCamV2.cpp b/libraries/AP_Camera/AP_Camera_MAVLinkCamV2.cpp
@@ -29,13 +29,13 @@ bool AP_Camera_MAVLinkCamV2::trigger_pic()
 
     // prepare and send message
     mavlink_command_long_t pkt {};
-    pkt.target_system = _sysid;
+    pkt.target_system = _sysid>255?0:_sysid;  // targets > 255 travel in the extended header
     pkt.target_component = _compid;
     pkt.command = MAV_CMD_IMAGE_START_CAPTURE;
     pkt.param3 = 1;             // number of images to take
     pkt.param4 = image_index+1; // starting sequence number
 
-    _link->send_message(MAVLINK_MSG_ID_COMMAND_LONG, (const char*)&pkt);
+    _link->send_message_target(MAVLINK_MSG_ID_COMMAND_LONG, (const char*)&pkt, _sysid, _compid);
 
     return true;
 }
@@ -51,7 +51,7 @@ bool AP_Camera_MAVLinkCamV2::record_video(bool start_recording)
 
     // prepare and send message
     mavlink_command_long_t pkt {};
-    pkt.target_system = _sysid;
+    pkt.target_system = _sysid>255?0:_sysid;  // targets > 255 travel in the extended header
     pkt.target_component = _compid;
 
     if (start_recording) {
@@ -63,7 +63,7 @@ bool AP_Camera_MAVLinkCamV2::record_video(bool start_recording)
         // param1 = 0, video stream id. 0 for all streams
     }
 
-    _link->send_message(MAVLINK_MSG_ID_COMMAND_LONG, (const char*)&pkt);
+    _link->send_message_target(MAVLINK_MSG_ID_COMMAND_LONG, (const char*)&pkt, _sysid, _compid);
 
     return true;
 }
@@ -78,7 +78,7 @@ bool AP_Camera_MAVLinkCamV2::set_zoom(ZoomType zoom_type, float zoom_value)
 
     // prepare and send message
     mavlink_command_long_t pkt {};
-    pkt.target_system = _sysid;
+    pkt.target_system = _sysid>255?0:_sysid;  // targets > 255 travel in the extended header
     pkt.target_component = _compid;
     pkt.command = MAV_CMD_SET_CAMERA_ZOOM;
     switch (zoom_type) {
@@ -91,7 +91,7 @@ bool AP_Camera_MAVLinkCamV2::set_zoom(ZoomType zoom_type, float zoom_value)
     }
     pkt.param2 = zoom_value;            // Zoom Value
 
-    _link->send_message(MAVLINK_MSG_ID_COMMAND_LONG, (const char*)&pkt);
+    _link->send_message_target(MAVLINK_MSG_ID_COMMAND_LONG, (const char*)&pkt, _sysid, _compid);
 
     return true;
 }
@@ -107,7 +107,7 @@ SetFocusResult AP_Camera_MAVLinkCamV2::set_focus(FocusType focus_type, float foc
 
     // prepare and send message
     mavlink_command_long_t pkt {};
-    pkt.target_system = _sysid;
+    pkt.target_system = _sysid>255?0:_sysid;  // targets > 255 travel in the extended header
     pkt.target_component = _compid;
     pkt.command = MAV_CMD_SET_CAMERA_FOCUS;
     switch (focus_type) {
@@ -126,7 +126,7 @@ SetFocusResult AP_Camera_MAVLinkCamV2::set_focus(FocusType focus_type, float foc
     }
     pkt.param2 = focus_value;
 
-    _link->send_message(MAVLINK_MSG_ID_COMMAND_LONG, (const char*)&pkt);
+    _link->send_message_target(MAVLINK_MSG_ID_COMMAND_LONG, (const char*)&pkt, _sysid, _compid);
 
     return SetFocusResult::ACCEPTED;
 }
@@ -242,12 +242,12 @@ void AP_Camera_MAVLinkCamV2::request_camera_information() const
         0,  // param6
         0,  // param7
         MAV_CMD_REQUEST_MESSAGE,
-        _sysid,
+        uint8_t(_sysid>255?0:_sysid),  // targets > 255 travel in the extended header
         _compid,
         0  // confirmation
     };
 
-    _link->send_message(MAVLINK_MSG_ID_COMMAND_LONG, (const char*)&pkt);
+    _link->send_message_target(MAVLINK_MSG_ID_COMMAND_LONG, (const char*)&pkt, _sysid, _compid);
 }
 
 #endif // AP_CAMERA_MAVLINKCAMV2_ENABLED
diff --git a/libraries/AP_Camera/AP_Camera_MAVLinkCamV2.h b/libraries/AP_Camera/AP_Camera_MAVLinkCamV2.h
@@ -70,7 +70,7 @@ class AP_Camera_MAVLinkCamV2 : public AP_Camera_Backend
     mavlink_camera_information_t _cam_info {}; // latest camera information received from camera
     uint32_t _last_caminfo_req_ms;  // system time that CAMERA_INFORMATION was last requested (used to throttle requests)
     class GCS_MAVLINK *_link;   // link we have found the camera on. nullptr if not seen yet
-    uint8_t _sysid;             // sysid of camera
+    uint32_t _sysid;            // sysid of camera
     uint8_t _compid;            // component id of gimbal
 };