You can read the data form your device and send data in the format as below:

To see the structure of the message sensor_msgs/LaserScan . Use the following command:

$ rosmsg show sensor_msgs/LaserScan

std_msgs/Header header
uint32 seq
time stamp
string frame_id
float32 angle_min
float32 angle_max
float32 angle_increment
float32 time_increment
float32 scan_time
float32 range_min
float32 range_max
float32[] ranges
float32[] intensities

Creating the laser node: create a new file:and put the following code in it:

#include <ros/ros.h>
#include <sensor_msgs/LaserScan.h>
int main(int argc, char** argv){
ros::init(argc, argv, "laser_scan_publisher");
ros::NodeHandle n;
ros::Publisher scan_pub = n.advertise<sensor_
msgs::LaserScan>("scan", 50);
unsigned int num_readings = 100;
double laser_frequency = 40;
double ranges[num_readings];
double intensities[num_readings];
int count = 0;
ros::Rate r(1.0);
while(n.ok()){
//generate some fake data for our laser scan
for(unsigned int i = 0; i < num_readings; ++i){
ranges[i] = count;
intensities[i] = 100 + count;
}
ros::Time scan_time = ros::Time::now();
Navigation Stack – Robot Setups
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//populate the LaserScan message
sensor_msgs::LaserScan scan;
scan.header.stamp = scan_time;
scan.header.frame_id = "base_link";
scan.angle_min = -1.57;
scan.angle_max = 1.57;
scan.angle_increment = 3.14 / num_readings;
scan.time_increment = (1 / laser_frequency) / (num_readings);
scan.range_min = 0.0;
scan.range_max = 100.0;
scan.ranges.resize(num_readings);
scan.intensities.resize(num_readings);
for(unsigned int i = 0; i < num_readings; ++i){
scan.ranges[i] = ranges[i];
scan.intensities[i] = intensities[i];
}
scan_pub.publish(scan);
++count;
r.sleep();
}
}

As you can see, we are going to create a new topic with the name scan and the message type sensor_msgs/LaserScan .