how_to_use_protobuf_function.md 13 KB
How to use protobuf functions to send & receive message
1 Introduction
Suppose there are two computers, PC-A and PC-B and they are far away from each other. You connect LiDAR with PC-A and for some reasons, you want to use point cloud message in PC-B. At this time, you may need to use the protobuf functions. Typically, there are two ways to achieve this goal.
PC-A send out the packets message to PC-B. PC-B receive the packet message and decode it , then PC-B get the point cloud message and use it.
PC-A decode the packets message, get the point cloud and send out the point cloud message to PC-B. PC-B receive the point cloud message and use it directly.
We offer both of these two ways but we recommend first method rather than second method because the point cloud message is very large and it may take up your bandwidth.
2 Send & Receive packets through Protobuf-UDP
We suppose you have already read Intro to parameters and you already have a basic idea about the config file. Lets look at the sender part first.
2.1 PC-A(Sender)
common:
msg_source: 1 #0: not use Lidar
#1: packet message comes from online Lidar
#2: packet message comes from ROS or ROS2
#3: packet message comes from Pcap file
#4: packet message comes from Protobuf-UDP
#5: point cloud comes from Protobuf-UDP
send_packet_ros: false #true: Send packets through ROS or ROS2(Used to record packet)
send_point_cloud_ros: false #true: Send point cloud through ROS or ROS2
send_packet_proto: true #true: Send packets through Protobuf-UDP
send_point_cloud_proto: false #true: Send point cloud through Protobuf-UDP
pcap_path: /home/robosense/lidar.pcap #The path of pcap file
Since the message come from online LiDAR, set msg_source = 1.
We want to send packets through protobuf-UDP, so set send_packet_proto = true.
lidar:
- driver:
lidar_type: RS128 #The lidar type - RS16, RS32, RSBP, RS128, RS80
frame_id: /rslidar #The frame id of message
device_ip: 192.168.1.200 #The device ip address
msop_port: 6699 #The msop port of lidar,default is 6699
difop_port: 7788 #The difop port of lidar, default is 7788
start_angle: 0 #The start angle of point cloud area
end_angle: 360 #The end angle of point cloud area
min_distance: 0.2 #The minimum distance of point cloud area
max_distance: 200 #The maximum distance of point cloud area
use_lidar_clock: false #true--Use the lidar clock as the message timestamp;false-- Use the system clock as the timestamp
angle_path: /home/robosense/angle.csv #The path of the angle calibration file. For the latest version lidars, there is no need to use this file.
Check the msop_port,difop_port to be correct.
proto:
point_cloud_recv_port: 60021 #The port number used for receiving point cloud
point_cloud_send_port: 60021 #The port number which the point cloud will be send to
point_cloud_send_ip: 127.0.0.1 #The ip address which the point cloud will be send to
msop_recv_port: 60022 #The port number used for receiving lidar msop packets
difop_recv_port: 60023 #The port number used for receiving lidar difop packets
msop_send_port: 60022 #The port number which the msop packets will be send to
difop_send_port: 60023 #The port number which the difop packets will be send to
packet_send_ip: 127.0.0.1 #The ip address which the lidar packets will be send to
We want to send packets so we only need to focus on three parameters, msop_send_port, difop_send_port, packet_send_ip. You can adjust them as you want.
2.2 PC-B(Receiver)
common:
msg_source: 4 #0: not use Lidar
#1: packet message comes from online Lidar
#2: packet message comes from ROS or ROS2
#3: packet message comes from Pcap file
#4: packet message comes from Protobuf-UDP
#5: point cloud comes from Protobuf-UDP
send_packet_ros: false #true: Send packets through ROS or ROS2(Used to record packet)
send_point_cloud_ros: true #true: Send point cloud through ROS or ROS2
send_packet_proto: false #true: Send packets through Protobuf-UDP
send_point_cloud_proto: false #true: Send point cloud through Protobuf-UDP
pcap_path: /home/robosense/lidar.pcap #The path of pcap file
Since the packets message come from protobuf-UDP, set msg_source = 4.
We want to watch the point cloud on ROS-Rviz, so set send_point_cloud_ros = true.
lidar:
- driver:
lidar_type: RS128 #The lidar type - RS16, RS32, RSBP, RS128, RS80
frame_id: /rslidar #The frame id of message
device_ip: 192.168.1.200 #The device ip address
msop_port: 6699 #The msop port of lidar,default is 6699
difop_port: 7788 #The difop port of lidar, default is 7788
start_angle: 0 #The start angle of point cloud area
end_angle: 360 #The end angle of point cloud area
min_distance: 0.2 #The minimum distance of point cloud area
max_distance: 200 #The maximum distance of point cloud area
use_lidar_clock: false #true--Use the lidar clock as the message timestamp;false-- Use the system clock as the timestamp
angle_path: /home/robosense/angle.csv #The path of the angle calibration file. For the latest version lidars, there is no need to use this file.
Check the lidar_type to be correct.
proto:
point_cloud_recv_port: 60021 #The port number used for receiving point cloud
point_cloud_send_port: 60021 #The port number which the point cloud will be send to
point_cloud_send_ip: 127.0.0.1 #The ip address which the point cloud will be send to
msop_recv_port: 60022 #The port number used for receiving lidar msop packets
difop_recv_port: 60023 #The port number used for receiving lidar difop packets
msop_send_port: 60022 #The port number which the msop packets will be send to
difop_send_port: 60023 #The port number which the difop packets will be send to
packet_send_ip: 127.0.0.1 #The ip address which the lidar packets will be send to
We want to receive packets so we only need to focus on two parameters, msop_recv_port, difop_recv_port. You must make sure they are same as the msop_send_port, difop_send_port set in the sender.
3 Send & receive point cloud through Protobuf-UDP
We suppose you have already read Intro to parameters and you already have a basic idea about the config file.
3.1 PC-A(Sender)
common:
msg_source: 1 #0: not use Lidar
#1: packet message comes from online Lidar
#2: packet message comes from ROS or ROS2
#3: packet message comes from Pcap file
#4: packet message comes from Protobuf-UDP
#5: point cloud comes from Protobuf-UDP
send_packet_ros: false #true: Send packets through ROS or ROS2(Used to record packet)
send_point_cloud_ros: false #true: Send point cloud through ROS or ROS2
send_packet_proto: false #true: Send packets through Protobuf-UDP
send_point_cloud_proto: true #true: Send point cloud through Protobuf-UDP
pcap_path: /home/robosense/lidar.pcap #The path of pcap file
Since the message come from online LiDAR, set msg_source = 1.
We want to send packets through protobuf-UDP, so set send_point_cloud_proto = true.
lidar:
- driver:
lidar_type: RS128 #The lidar type, must be set correctly
frame_id: /rslidar #The frame id of message
device_ip: 192.168.1.200 #The device ip address
msop_port: 6699 #The msop port of lidar,default is 6699
difop_port: 7788 #The difop port of lidar, default is 7788
start_angle: 0 #The start angle of point cloud area
end_angle: 360 #The end angle of point cloud area
min_distance: 0.2 #The minimum distance of point cloud area
max_distance: 200 #The maximum distance of point cloud area
use_lidar_clock: false #true--Use the lidar clock as the message timestamp;false-- Use the system clock as the timestamp
angle_path: /home/robosense/angle.csv #The path of the angle calibration file. For the latest version lidars, there is no need to use this file.
Check the lidar_type,msop_port,difop_port to be correct.
proto:
point_cloud_recv_port: 60021 #The port number used for receiving point cloud
point_cloud_send_port: 60021 #The port number which the point cloud will be send to
point_cloud_send_ip: 127.0.0.1 #The ip address which the point cloud will be send to
msop_recv_port: 60022 #The port number used for receiving lidar msop packets
difop_recv_port: 60023 #The port number used for receiving lidar difop packets
msop_send_port: 60022 #The port number which the msop packets will be send to
difop_send_port: 60023 #The port number which the difop packets will be send to
packet_send_ip: 127.0.0.1 #The ip address which the lidar packets will be send to
We want to send point cloud so we only need to focus on two things, point_cloud_send_port, point_cloud_send_ip. You can adjust them as you want.
3.2 PC-B(Receiver)
common:
msg_source: 5 #0: not use Lidar
#1: packet message comes from online Lidar
#2: packet message comes from ROS or ROS2
#3: packet message comes from Pcap file
#4: packet message comes from Protobuf-UDP
#5: point cloud comes from Protobuf-UDP
send_packet_ros: false #true: Send packets through ROS or ROS2(Used to record packet)
send_point_cloud_ros: true #true: Send point cloud through ROS or ROS2
send_packet_proto: false #true: Send packets through Protobuf-UDP
send_point_cloud_proto: false #true: Send point cloud through Protobuf-UDP
pcap_path: /home/robosense/lidar.pcap #The path of pcap file
Since the point cloud message come from protobuf-UDP, set msg_source = 5.
We want to watch the point cloud on ROS-Rviz, so set send_point_cloud_ros = true.
proto:
point_cloud_recv_port: 60021 #The port number used for receiving point cloud
point_cloud_send_port: 60021 #The port number which the point cloud will be send to
point_cloud_send_ip: 127.0.0.1 #The ip address which the point cloud will be send to
msop_recv_port: 60022 #The port number used for receiving lidar msop packets
difop_recv_port: 60023 #The port number used for receiving lidar difop packets
msop_send_port: 60022 #The port number which the msop packets will be send to
difop_send_port: 60023 #The port number which the difop packets will be send to
packet_send_ip: 127.0.0.1 #The ip address which the lidar packets will be send to
We want to receive packets so we only need to focus on one things, point_cloud_recv_port. You must make sure they are same as the point_cloud_send_port set in the sender.