best way to create a topic

asked 2013-08-14 03:00:26 -0500

hvn
72 ●34 ●41 ●48

Hi,

I have 2 nodes that need 1-way communication of an array of floating point values, so I want node 1 to publish to a topic (e.g. ref), and node 2 to subscribe to that topic. I've searched on how to create a node with topic, but the tutorial only shows a message topic. Now I've tried 2 approaches: using a yaml file and using a launch file according to working examples, but so far neither creates a new topic. So the question is: how do I best create a new topic for 2 existing nodes ?

Thanks

edit retag flag offensive close merge delete

add a comment

3

answered 2013-08-14 04:02:51 -0500

thebyohazard
3542 ●52 ●68 ●83

updated 2013-08-15 02:37:18 -0500

felix k

1650 ●14 ●36 ●49

I'm not sure you understand the concept of topics and messages quite correctly. It might help you to go through the main tutorials again, in particular UnderstandingTopics and WritingPublisherSubscriber(c++).

Messages are always broadcast on topics. To create a topic, one node needs to advertise that they will broadcast messages on that topic. Then another node subscribes to that topic and receives all messages broadcast on that topic.

edit flag offensive delete link

Comments

Further, the message type that you are likely interested in using will be one of the multiarray datatypes in the http://www.ros.org/wiki/std_msgs/

SL Remy ( 2013-08-15 06:40:20 -0500 )edit

TY @tbh and @trinighost. I did understand but just a minor misconception. The multiarray type did the trick.

hvn ( 2013-08-15 08:23:01 -0500 )edit

add a comment

0

answered 2018-08-15 06:24:00 -0500

ameni
1 ●1 ●1

HI, I'm using a roboteq magsensor, and I want to read data from.

so I'm going to use Roboteq Linux API to interface one the sensor form a C++ ROS node through CANbus . The problem is I didn't come to know how to work: it's only one node that's gonna read from the sensor , how to use topic in this situation ?