How to communicate with other ros nodes

asked 2022-02-25 09:32:40 -0500

tadtom gravatar image

Right now I have the ros master node and octomap_server node working on my robot pepper and I want to run octomap on my own linux machine.

But right now, I get the error :

RLException: Unable to contact my own server at [http://192.168.11.173:44645/]. This usually means that the network is not configured properly.

A common cause is that the machine cannot connect to itself.  Please check for errors by running:
ping 192.168.11.173

For more tips, please see

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

So, I did check that website and tried pinging the machines which worked and then tried to use netcat which only worked in one direction.

my computer with ubuntu 18 : nc -l 1300
pepper robot : nc 192.168.11.168 1300

this worked fine

my computer with ubuntu 18 : nc pepper4 1300
pepper robot : nc -l 1300

This doesn't work

From now, I don't know what to do to try to solve this problem and I'm not really sure if I understood properly what's happening.

As I understand this from http://wiki.ros.org/ROS/Technical%20Overview,

  • my octomap node looks for the octomap server so it sends an xml/rpc message to the master without problem
  • the master sends the port of the octomap_server node via xml/rpc
  • the octomap node then tries to connect to the octomap_server using tcp node but can't ( I don't understand why )

If someone could help me have a better understand on this or lead me to a solution, that would be awesome.

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