[ros-users] multi-machine communication problem

[Ken Conley]

It's probably the case that your laptop hostname is not route-able
from the basestation. There are many ways to resolve this. Please see:

http://www.ros.org/wiki/ROS/NetworkSetup

hope this helps,
 - Ken

On Thu, Jul 22, 2010 at 6:21 PM, Adam Leeper <aleeper at stanford.edu> wrote:
> Hi-
>
> I am trying to run a camera that is plugged into my laptop and I want to
> publish messages that can be received by processes running on the robot
> and/or basestation. I have correctly set the ROS_MASTER_URI to point to the
> robot. I can tell because if I rostopic list on my laptop I get all the
> robot topics, and if I run rviz I can also see all the robot state and
> sensor data. For some reason though, it seems my laptop is not able to
> publish messages back to the robot or basestation. The laptop is physically
> connected to the same switch as the basestation and robot through an
> ethernet cable.
>
> From my laptop I have a node publishing an image topic, called
> /camera/image. On both the laptop and the basestation I have image_view
> nodes subscribed to the /camera/image.
>
> On my laptop the image_view window shows the image as expected. Doing
> rostopic info /camera/image shows that there are two image_view processes
> subscribed to the topic (one from the laptop and one from the basestation).
>
> rostopic info /camera/image
> Type: sensor_msgs/Image
> Publishers:
>  * /uvc_cam (http://jks-g51:59684/)
> Subscribers:
>  * /image_view_1279845826710500129 (http://jks-g51:33511/)
>  * /image_view_1279846165570567012 (http://stair4-basestation:41138/)
>
>
>
> On the basestation the image_view window does NOT show the image at all.
> Doing rostopic hz/echo /camera/image shows no imcoming messages. However,
> rostopic list still shows the /camera/image topic, and doing rostopic info
> shows the same info as from the laptop.
>
> rostopic info /camera/image
> Type: sensor_msgs/Image
>
> Publishers:
>  * /uvc_cam (http://jks-g51:59684/)
>
> Subscribers:
>  * /image_view_1279845826710500129 (http://jks-g51:33511/)
>  * /image_view_1279846165570567012 (http://stair4-basestation:41138/)
>
>
> As a final test, I tried plugging the camera into the basestation and doing
> the same thing. In this case both the basestation AND the laptop
> successfully get the image topics, as seen through image_view and the
> various rostopic tools.
>
> I don't understand why the messages aren't getting transmitted outbound from
> the laptop. It seems everything else works fine, including messages from the
> basestation or robot to the laptop. Can anyone see what is wrong with this
> or give me places to look?
>
> Thanks!
> --Adam
>
>
>
>
>
>
> Adam Leeper
> Stanford University
> aleeper at stanford.edu
> 719.358.3804
>
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