Hello, all As i am a newbie of ROS i'm struggling with hokuyo_node package with running two hokuyo( UTM-LX30) device. first i actually tried the

<node name="Laser1" pkg="hokuyo_node" type="hokuyo_node">
    <param name="port" type="string" value ="/dev/ttyACM0"/>
    <param name="calibrate_time" type="bool" value="false"/>
    <param name="frame_id" type="string" value="/hokuyo"/>
    <param name="min_ang" type="double" value ="-1.57"/>
    <param name="max_ang" type="double" value ="1.57"/>
    <remap from="scan" to="scan1"/> 
    <param name="intensity" type="bool" value="true"/>

</node>
<node name="Laser2" pkg="hokuyo_node" type="hokuyo_node">
    <param name="port" type="string" value ="/dev/ttyACM1"/>
    <param name="calibrate_time" type="bool" value="false"/>
    <param name="frame_id" type="string" value="/hokuyo"/>
    <param name="min_ang" type="double" value ="-1.57"/>
    <param name="max_ang" type="double" value ="1.57"/>
    <param name="intensity" type="bool" value="true"/>
    <param name="time_offset" type="double" value="0.7"/>
    <remap from="scan" to="scan2"/> 
</node>

but this makes the second hokuyo didn't work at all. so i seperated the node in hokuyo1.launch, hokuyo2.launch files. when i run these files, only former(1st) hokuyo runs correctly, the later one runs for only couple of sequences(no more than 1sec) and stops. When i stop the node and rerun, It says error "timeout reached".

I tried several ways to solve this annoying problem.

1. publishing. I though it might have been a problem of publishing in a same "scan". I tried to make 2 seperate scan pub ("scan1", "scan2") not to make a overlap in "scan".

---

scan_pub_1(node_handle_.advertise<sensor_msgs::LaserScan>("scan1", 100),
        diagnostic_,
        diagnostic_updater::FrequencyStatusParam(&desired_freq_, &desired_freq_, 0.05),
        diagnostic_updater::TimeStampStatusParam()),


scan_pub_2(node_handle_.advertise<sensor_msgs::LaserScan>("scan2", 100),
        diagnostic_,
        diagnostic_updater::FrequencyStatusParam(&desired_freq_, &desired_freq_, 0.05),
        diagnostic_updater::TimeStampStatusParam()),
    hokuyo_diagnostic_task_("Hokuyo Diagnostics", boost::bind(&HokuyoNode::connectionStatus, this, _1))
  {
    desired_freq_ = 0;
    driver_.useScan_ = boost::bind(&HokuyoNode::publishScan, this, _1);
    driver_.setPostOpenHook(boost::bind(&HokuyoNode::postOpenHook, this));

But it didn't work.

"2" . Poll. It might be the poll problem, that

---

int
hokuyo::Laser::laserReadline(char *buf, int len, int timeout)
{
  int current=0;

  struct pollfd ufd[1];
  int retval;
  ufd[0].fd = laser_fd_;
  ufd[0].events = POLLIN;

  if (timeout == 0)
    timeout = -1; // For compatibility with former behavior, 0 means no timeout. For poll, negative means no timeout.

  while (true)
  {
    if (read_buf_start == read_buf_end) // Need to read?
    {
      if ((retval = poll(ufd, 1, timeout)) < 0)
        HOKUYO_EXCEPT(hokuyo::Exception, "poll failed   --  error = %d: %s", errno, strerror(errno));

      if (retval == 0)
        HOKUYO_EXCEPT(hokuyo::TimeoutException, "timeout reached");

      if (ufd[0].revents & POLLERR)
        HOKUYO_EXCEPT(hokuyo::Exception, "error on socket, possibly unplugged");

      int bytes = read(laser_fd_, read_buf, sizeof(read_buf));
      if (bytes == -1 && errno != EAGAIN && errno != EWOULDBLOCK)
        HOKUYO_EXCEPT(hokuyo::Exception, "read failed");
      read_buf_start = 0;
      read_buf_end = bytes;
    }

    while (read_buf_end != read_buf_start)
    {
      if (current == len - 1)
      {
        buf[current] = 0;
        HOKUYO_EXCEPT(hokuyo::Exception, "buffer filled without end of line being found");
      }

      buf[current] = read_buf[read_buf_start++];
      if (buf[current++] == '\n')
      {
        buf[current] = 0;
        return current;
      }
    }

I'm not sure what to manage in this code.

Can someone help?? I'm kind of desperate because I got a business trip next week :(