diff --git a/pps_wiki/faq.md b/pps_wiki/faq.md index db63466c483dc18c6384ed8d87020feabb4069cf..3fa72033042c2f13878af69611076e378b411a5d 100644 --- a/pps_wiki/faq.md +++ b/pps_wiki/faq.md @@ -282,4 +282,10 @@ if (true) my_subscriber = nodeHandle.subscribe("/fortytwo",1,fortytwoCallback); } ``` -This would work if it is in the ``main()`` function of a node, but if it is in another function then you may need to declare the subscriber as a class variable. \ No newline at end of file +This would work if it is in the ``main()`` function of a node, but if it is in another function then you may need to declare the subscriber as a class variable. + +To observe any message published on a particular topic, after launching your node, open a separate command window and type the command: +``` +rostopic echo /namespace/topicname +``` +where ``/namespace/topicname`` needs to be replace with the topic that you wish to echo. Any messages received by this topic will be directly printed out in the command window. \ No newline at end of file