Convert rostopic pub into c++ code

answered 2020-06-22 19:19:35 -0600

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The answer to the question you asked is below. However I think there is a hidden question here. What have you tried so far to make a publisher in C++ and what happened when it didn't work?

Take a look at the tutorial for writing a publisher in C++.

You will need to make the following changes:

Change the name of the node on line 47 to something more appropriate for what you are doing, e.g. "gripper_controller"
Change the topic name on line 73 to be the topic you want to publish to, in this case "gripper_angle".
Change the header file on line 28 to the data type you want to publish, which is "std_msgs/UInt16.h"
Change the type of the Publisher on line 73 to be UInt16.
Remove the while loop and have it just publish data once, with the value you want to publish. If you are trying to make a utility you can call from the command line with an argument, then you should get that value from a command line argument. There are plenty of tutorials on the web about how to parse command line arguments in C++.

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i have coded this but there is not echo from the function clodeGripper().

  ros::NodeHandle node_handle;
  ros::Publisher gripper_angle = node_handle.advertise<std_msgs::UInt16>("angle", 10);
  std_msgs::UInt16 msg;
  msg.data = 180;
  gripper_angle.publish(msg);

Calvin ( 2020-06-23 04:20:33 -0600 )edit

Please post your complete code, and if there is an error output when compiling it or running it, post that as well. Use a GitHub Gist if it's long.

Geoff ( 2020-06-23 18:34:29 -0600 )edit

Maybe I can redirect you here, https://answers.ros.org/question/3556...

Calvin ( 2020-06-23 19:59:40 -0600 )edit

That question duplicates this one, with different wording and a little different information. Please do not do that.
That question still doesn't include your entire source.

Geoff ( 2020-06-23 20:26:45 -0600 )edit

I am sorry for the mistake that I have made. I am new to posting questions online and asking for help. this is the link to both the files of the publisher and the subscriber for the question above.

https://github.com/MojoZuikie/eti_mov...

Calvin ( 2020-06-23 21:25:18 -0600 )edit

The problem is that you are creating a publisher in the closeGripper() and openGripper() functions, using that to publish a message, then exiting the function. It is likely that the publisher is being cleaned up by going out of scope before it even has a chance to publish the message, and even if it publishes the message it probably does so before any subscribers listening to that topic get connected to the publisher. You need to create a single publisher for the topic once in your node's set up, then use that throughout.

Geoff ( 2020-06-24 19:47:16 -0600 )edit

I found out a way to control the gripper using the code above. Thanks Very much.

Calvin ( 2020-06-25 00:03:34 -0600 )edit

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