08_how_to_decode_pcap_file.md

8 How to decode PCAP file

8.1 Introduction

This document illustrates how to decode PCAP file, and send point cloud to ROS.

Please make sure you have read the LiDAR user-guide and Intro to parameters before reading this document.

8.2 Steps

8.2.1 Get the LiDAR port number

Please check the LiDAR user-guide, or use the 3rd-party tool(such as WireShark), to get your LiDAR's MSOP port number and DIFOP port number. The default values are msop-6699, difop-7788.

8.2.2 Set up the configuration file

Set up the configuration file config.yaml.

8.2.2.1 common part

common:
  msg_source: 3                                       
  send_packet_ros: false                                
  send_point_cloud_ros: true                            
  send_packet_proto: false                              
  send_point_cloud_proto: false                         

The messages come from the PCAP bag, so set msg_source = 3.

Send point cloud to ROS, so set send_point_cloud_ros = true.

8.2.2.2 lidar-driver part

lidar:
  - driver:
      lidar_type: RS128            
      msop_port: 6699             
      difop_port: 7788           
      start_angle: 0               
      end_angle: 360              
      min_distance: 0.2            
      max_distance: 200           
      use_lidar_clock: false      
      pcap_path: /home/robosense/lidar.pcap               

Set the pcap_path to the absolute path of the PCAP file.

Set the lidar_type to your LiDAR type.

Set the msop_port and difop_port to the port numbers of your LiDAR.

8.2.2.3 lidar-ros part

ros:
  ros_frame_id: rslidar           
  ros_recv_packet_topic: /rslidar_packets    
  ros_send_packet_topic: /rslidar_packets   
  ros_send_point_cloud_topic: /rslidar_points      

Set the ros_send_point_cloud_topic to the topic you want to send to.

8.2.3 Run

Run the program.