# Unable to subscribe to vehicle_command_position topic Source: https://forum.modalai.com/topic/3453/unable-to-subscribe-to-vehicle_command_position-topic Category: General Questions (https://forum.modalai.com/category/2/general-questions) Posted: 2024-05-18 23:47:38 UTC by Darshit Desai Replies: 2 · Views: 1118 ## Darshit Desai · 2024-05-18 23:47:38 UTC Hi @Moderator I have been trying to subscribe to vehicle_local_position ROS2 PX4 topic in my code but that wasn't working so I checked by echoing the topic directly from the terminal and it shows this error? ![c39768a1-c454-4f6f-a893-6aca2dc148c2-image.png](https://forum.modalai.com/assets/uploads/files/1716076011245-c39768a1-c454-4f6f-a893-6aca2dc148c2-image.png) After doing some search online, I found that the PX4 and px4_msgs version might be different, since I am using voxl_ros2_foxy any ideas why this would be happening? Voxl version info ``` voxl2:~/ros2_ws/src/Project_LegionAir(ROS2-port)$ voxl-version -------------------------------------------------------------------------------- system-image: 1.7.1-M0054-14.1a-perf-nightly-20231025 kernel: #1 SMP PREEMPT Thu Oct 26 03:25:38 UTC 2023 4.19.125 -------------------------------------------------------------------------------- hw version: M0054 -------------------------------------------------------------------------------- voxl-suite: 1.1.2 -------------------------------------------------------------------------------- Packages: Repo: http://voxl-packages.modalai.com/ ./dists/qrb5165/sdk-1.1/binary-arm64/ Last Updated: 2024-05-07 06:01:21 List: libmodal-cv 0.4.0 libmodal-exposure 0.1.0 libmodal-journal 0.2.2 libmodal-json 0.4.3 libmodal-pipe 2.9.2 libqrb5165-io 0.4.2 libvoxl-cci-direct 0.2.1 libvoxl-cutils 0.1.1 mv-voxl 0.1-r0 qrb5165-bind 0.1-r0 qrb5165-dfs-server 0.2.0 qrb5165-imu-server 1.0.1 qrb5165-rangefinder-server 0.1.1 qrb5165-slpi-test-sig 01-r0 qrb5165-system-tweaks 0.2.3 qrb5165-tflite 2.8.0-2 voxl-bind-spektrum 0.1.0 voxl-camera-calibration 0.5.3 voxl-camera-server 1.8.9.1 voxl-configurator 0.4.8 voxl-cpu-monitor 0.4.7 voxl-docker-support 1.3.0 voxl-elrs 0.1.3 voxl-esc 1.3.7 voxl-feature-tracker 0.3.2 voxl-flow-server 0.3.3 voxl-gphoto2-server 0.0.10 voxl-jpeg-turbo 2.1.3-5 voxl-lepton-server 1.2.0 voxl-libgphoto2 0.0.4 voxl-libuvc 1.0.7 voxl-logger 0.3.5 voxl-mavcam-manager 0.5.3 voxl-mavlink 0.1.1 voxl-mavlink-server 1.3.2 voxl-microdds-agent 2.4.1-0 voxl-modem 1.0.8 voxl-mongoose 7.7.0-1 voxl-mpa-to-ros 0.3.7 voxl-mpa-to-ros2 0.0.2 voxl-mpa-tools 1.1.3 voxl-neopixel-manager 0.0.3 voxl-opencv 4.5.5-2 voxl-portal 0.6.3 voxl-px4 1.14.0-2.0.63 voxl-px4-imu-server 0.1.2 voxl-px4-params 0.3.3 voxl-qvio-server 1.0.0 voxl-remote-id 0.0.9 voxl-ros2-foxy 0.0.1 voxl-streamer 0.7.4 voxl-suite 1.1.2 voxl-tag-detector 0.0.4 voxl-tflite-server 0.3.2 voxl-utils 1.3.3 voxl-uvc-server 0.1.6 voxl-vision-hub 1.7.3 voxl2-system-image 1.7.1-r0 voxl2-wlan 1.0-r0 -------------------------------------------------------------------------------- ``` ## Reply by brahim · 2024-05-20 15:20:49 UTC What px4_msgs branch or tag are you using? Please post the branch name. The px4_msgs repo branch is in lockstep with the PX4 branch release, so if there is a mismatch I would expect deserialization issues. ## Reply by brahim · 2024-05-21 13:45:41 UTC (in reply to brahim) @Darshit-Desai Here is the output from echo'ing local position. ``` voxl2:~/colcon_ws$ ros2 topic list /fmu/in/obstacle_distance /fmu/in/offboard_control_mode /fmu/in/onboard_computer_status /fmu/in/sensor_optical_flow /fmu/in/telemetry_status /fmu/in/trajectory_setpoint /fmu/in/vehicle_attitude_setpoint /fmu/in/vehicle_command /fmu/in/vehicle_mocap_odometry /fmu/in/vehicle_rates_setpoint /fmu/in/vehicle_trajectory_bezier /fmu/in/vehicle_trajectory_waypoint /fmu/in/vehicle_visual_odometry /fmu/out/failsafe_flags /fmu/out/position_setpoint_triplet /fmu/out/sensor_combined /fmu/out/timesync_status /fmu/out/vehicle_attitude /fmu/out/vehicle_control_mode /fmu/out/vehicle_local_position /fmu/out/vehicle_odometry /fmu/out/vehicle_status /parameter_events /rosout voxl2:~/colcon_ws$ ros2 topic echo /fmu/out/vehicle_local_position timestamp: 1716299017260605 timestamp_sample: 1716299017259933 xy_valid: false z_valid: true v_xy_valid: false v_z_valid: true x: -0.015882886946201324 y: -0.006520443130284548 z: 3.26619815826416 delta_xy: [-9.292006097894046e-08, -1.9959152552928572e-07] xy_reset_counter: 1 delta_z: 0.0 z_reset_counter: 1 vx: 0.0007984319818206131 vy: -0.001192234456539154 vz: 0.006735446862876415 z_deriv: 0.014136962592601776 delta_vxy: [-1.0643154382705688e-05, -2.2861408069729805e-05] vxy_reset_counter: 1 delta_vz: 1.583993434906006e-05 vz_reset_counter: 1 ax: 0.042993903160095215 ay: -0.06323475390672684 az: -0.10127022862434387 heading: -0.12067540735006332 delta_heading: 0.0 heading_reset_counter: 0 heading_good_for_control: false xy_global: false z_global: false ref_timestamp: 0 ref_lat: .nan ref_lon: .nan ref_alt: .nan dist_bottom: 0.10000000149011612 dist_bottom_valid: false dist_bottom_sensor_bitfield: 0 eph: 0.012850395403802395 epv: 0.3351651430130005 evh: 0.04047877714037895 evv: 0.06853056699037552 dead_reckoning: true vxy_max: .inf vz_max: .inf hagl_min: .inf hagl_max: .inf --- ``` Voxl version ``` system-image: 1.7.4-M0054-14.1a-perf kernel: #1 SMP PREEMPT Fri Feb 9 21:59:24 UTC 2024 4.19.125 -------------------------------------------------------------------------------- hw platform: M0054 mach.var: 1.0 -------------------------------------------------------------------------------- voxl-suite: 1.1.3-1 Packages: Repo: http://voxl-packages.modalai.com/ ./dists/qrb5165/sdk-1.1/binary-arm64/ Last Updated: 2024-05-21 13:30:13 List: kernel-module-voxl-fsync-mod-4.19.125 1.0-r0 kernel-module-voxl-gpio-mod-4.19.125 1.0-r0 kernel-module-voxl-platform-mod-4.19.125 1.0-r0 libmodal-cv 0.4.0 libmodal-exposure 0.1.0 libmodal-journal 0.2.2 libmodal-json 0.4.3 libmodal-pipe 2.9.2 libqrb5165-io 0.4.2 libvoxl-cci-direct 0.2.1 libvoxl-cutils 0.1.1 mv-voxl 0.1-r0 qrb5165-bind 0.1-r0 qrb5165-dfs-server 0.2.0 qrb5165-imu-server 1.0.1 qrb5165-rangefinder-server 0.1.1 qrb5165-slpi-test-sig 01-r0 qrb5165-system-tweaks 0.2.6 qrb5165-tflite 2.8.0-2 voxl-bind-spektrum 0.1.0 voxl-camera-calibration 0.5.3 voxl-camera-server 1.8.9 voxl-ceres-solver 2:1.14.0-10 voxl-configurator 0.5.2 voxl-cpu-monitor 0.4.7 voxl-docker-support 1.3.0 voxl-elrs 0.1.3 voxl-esc 1.4.0 voxl-feature-tracker 0.3.2 voxl-flow-server 0.3.3 voxl-fsync-mod 1.0-r0 voxl-gphoto2-server 0.0.10 voxl-gpio-mod 1.0-r0 voxl-jpeg-turbo 2.1.3-5 voxl-lepton-server 1.2.0 voxl-libgphoto2 0.0.4 voxl-libuvc 1.0.7 voxl-logger 0.3.5 voxl-mavcam-manager 0.5.3 voxl-mavlink 0.1.1 voxl-mavlink-server 1.3.2 voxl-microdds-agent 2.4.1-0 voxl-modem 1.0.8 voxl-mongoose 7.7.0-1 voxl-mpa-to-ros 0.3.7 voxl-mpa-to-ros2 0.0.2 voxl-mpa-tools 1.1.3 voxl-neopixel-manager 0.0.3 voxl-open-vins 0.4.4 voxl-open-vins-server 0.2.18 voxl-opencv 4.5.5-2 voxl-platform-mod 1.0-r0 voxl-portal 0.6.3 voxl-px4 1.14.0-2.0.63 voxl-px4-imu-server 0.1.2 voxl-px4-params 0.3.3 voxl-qvio-server 1.0.0 voxl-remote-id 0.0.9 voxl-ros2-foxy 0.0.1 voxl-streamer 0.7.4 voxl-suite 1.1.3-1 voxl-tag-detector 0.0.4 voxl-tflite-server 0.3.1 voxl-utils 1.3.8 voxl-uvc-server 0.1.6 voxl-vision-hub 1.7.3 voxl2-system-image 1.7.4-r0 voxl2-wlan 1.0-r0 -------------------------------------------------------------------------------- ``` px4_msgs branch ``` voxl2:~/colcon_ws/src/px4_msgs(release/1.14)$ git branch * release/1.14 ```