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When using roslibjs, getting value of some params returns empty.

asked 2013-05-07 06:41:32 -0500

Jamison gravatar image

Hello, I am trying to programmatically fetch params from my ROS instance using roslibjs. When fetching some params, the value returns successfully, however with other params the value returned is empty.

Here is a snippet of the code in question:

var bridge = new ROSLIB.Ros();
bridge.on('connection', onConnect);
bridge.on('error', onError);


var param = new ROSLIB.Param({
    ros: bridge,
    name: name

param.get(function(value) {
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It would be helpful if you could also post examples of some parameters that work and some that fail. For example, using rosparam dump param_name to show the type/value of each parameter.

Jeremy Zoss gravatar image Jeremy Zoss  ( 2013-05-07 07:08:32 -0500 )edit

I'll give it my best shot! ros_version returns "fuerte". "rrHardwareStatus4Enable", my own custom parameter, returns blank. Does that help?

Jamison gravatar image Jamison  ( 2013-05-07 07:53:43 -0500 )edit

2 Answers

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answered 2013-05-07 10:41:23 -0500

Jamison gravatar image

Hi all, I wanted to post the answer to my question! I figured it out!

To get the value of a param from ROS using roslibjs, you must supply the full parameter name, not a truncated version!

My application was putting all of the params that ROS reported into a collapsible/expandable tree, and was stripping the /blah/ prefix from params like /blah/blahparam.

To reiterate, to get the value of a param from ROS, you must specify /blah/blahparam, not just blahparam.


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answered 2013-05-07 10:41:45 -0500

rtoris288 gravatar image

There was an issue with roslibjs r5 and earlier:

r6 was pushed today with fixes and posted to the CDN as well.

If this still isn't working, verify the parameter is actually set using rosparam get <param_name> in the console.

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Asked: 2013-05-07 06:41:32 -0500

Seen: 550 times

Last updated: May 07 '13