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PR2 rqt_plot has the error TopicCompleter.update_topics(): could not get message class

asked 2014-08-28 15:09:55 -0500

Winston gravatar image

updated 2014-11-22 17:05:48 -0500

ngrennan gravatar image

I have written a publisher in PR2's computer to publish message whose type is "beginner_tutorials/Num" on topic "/chatter2". Then I want to plot the data from this topic. I cannot use rqt_plot in PR2's computer because it does not support graphics. So I open a terminal in my own computer(which of course supports graphics) and export ROS_MASTER_URI=[PR2 computer's address] so that I can communicate with PR2's roscore. In this local terminal, I use rqt_plot to plot the data like: rqt_plot /chatter2/data, but there is an error:

TopicCompleter.update_topics(): could not get message class for topic type "beginner_tutorials/Num" on topic "/chatter2"

It seems that rqt_plot cannot subscribe to the topic. But curiously, indeed I can "rostopic list" this topic in the same terminal. So how to let rqt_plot subscribe successfully to the topic and plot my data?

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answered 2014-09-16 00:59:03 -0500

Winston gravatar image

updated 2014-09-16 01:09:16 -0500

I know the answer now. If I want rqt_plot to subscribe to the topic /chatter2 in my local terminal, I have to get the package in my local computer and 'rosmake' it so that my local computer has the definition of the message type of the topic.

That is to say, I should put the package in my local computer's workspace, source my workspace and then run 'rosmake' in the package directory. After that, rqt_plot can plot the data got from this topic.

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ROS won't eat unless there's source on everything!

porkPy gravatar image porkPy  ( 2019-03-27 07:59:37 -0500 )edit

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Asked: 2014-08-28 15:09:55 -0500

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Last updated: Sep 16 '14