When I set fixed_resolution to true, "Single Fixed Size" sometimes changes between launches

[atinfinity]

I tried to use YDLIDAR X4PRO with your ROS 2 package.
I used X4-Pro.yaml as parameter file. In this file, fixed_resolution is true.
On the other hands, Single Fixed Size sometimes changes between launches.

Is this expected behavior?

Environment

• Ubuntu 22.04(x86_64)
• ROS 2 Humble
• YDLidar-SDK YDLIDAR/YDLidar-SDK@1140e64
• ydlidar_ros2_driver 91e86db
• YDLIDAR X4PRO https://www.ydlidar.com/products/view/21.html

Steps to reproduce

I installed SDK.

git clone https://github.com/YDLIDAR/YDLidar-SDK.git
mkdir -p YDLidar-SDK/build
cd YDLidar-SDK/build
cmake ..
make
sudo make install

And, I install ydlidar_ros2_driver package.

mkdir -p ~/ydlidar_ros2_ws/src
cd ~/ydlidar_ros2_ws/src
git clone https://github.com/YDLIDAR/ydlidar_ros2_driver.git -b humble
cd ..
rosdep install -y -i --from-paths src/ydlidar_ros2_driver --rosdistro humble
colcon build --symlink-install --packages-select ydlidar_ros2_driver
source ~/ydlidar_ros2_ws/install/setup.bash

I launched ydlidar_ros2_driver. I used X4-Pro.yaml as parameter file.

ros2 launch ydlidar_ros2_driver ydlidar_launch.py params_file:=$HOME/ydlidar_ros2_ws/src/ydlidar_ros2_driver/params/X4-Pro.yaml

As a result, The following message is displayed.

[ydlidar_ros2_driver_node-1] Firmware version: 3.1
[ydlidar_ros2_driver_node-1] Hardware version: 3
[ydlidar_ros2_driver_node-1] Model: S2PRO
[ydlidar_ros2_driver_node-1] [2025-01-31 11:20:43][info] Scan Frequency: 10.00Hz
[ydlidar_ros2_driver_node-1] [2025-01-31 11:20:43][info] Fixed Size: 720
[ydlidar_ros2_driver_node-1] [2025-01-31 11:20:43][info] Sample Rate: 5.00K
[ydlidar_ros2_driver_node-1] [2025-01-31 11:20:43][info] Scan Frequency: 10.00Hz
[ydlidar_ros2_driver_node-1] [2025-01-31 11:20:43][info] Fixed Size: 720
[ydlidar_ros2_driver_node-1] [2025-01-31 11:20:43][info] Sample Rate: 5.00K
[ydlidar_ros2_driver_node-1] [2025-01-31 11:20:43][info] Scan Frequency: 10.00Hz
[ydlidar_ros2_driver_node-1] [2025-01-31 11:20:43][info] Fixed Size: 720
[ydlidar_ros2_driver_node-1] [2025-01-31 11:20:43][info] Sample Rate: 5.00K
[ydlidar_ros2_driver_node-1] [2025-01-31 11:20:43][info] Single Fixed Size: 450
[ydlidar_ros2_driver_node-1] [2025-01-31 11:20:43][info] Sample Rate: 5.00K
[ydlidar_ros2_driver_node-1] [2025-01-31 11:20:43][info] Successed to check the lidar, Elapsed time 310 ms