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rostopic echo doesn't return any data

asked 2022-01-09 13:43:06 -0500

jgauthier gravatar image

So, kind of a weird problem.

I set up ROS on an RPi with a kinect. I am generating a map with slam_gmapping. It works - but it's terribly slow. So, I decided to off load the SLAM process to an actual PC that is much faster.

I did - and it seems to be working fine. However, on the raspberry pi I can no longer see the map. for instance rostopic echo /map never returns, which tells me nothing is being published.

However, on the PC I can echo the map just fine.

Likewise, I have depthimage_to_laserscan running on the Rpi. On both the pi and the PC I can easily echo /scan.

It seems to be specific to running slam_gmapping on the PC that I can't echo the map on the Rpi.

What could cause that?

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answered 2022-01-10 05:39:04 -0500

osilva gravatar image

Please take a look at previous question:#q322394

The most common issue is: setting ROS_HOSTNAME or ROS_MASTER_URI to a hostname without a way for the machines to resolve the hostnames into IPs (or setting ROS_IP to a hostname, instead of an IP).

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I'm using all IPs. But this doesn't make sense to me. On machine A (which is running roscore) I can echo all the topics except for the one published by machine B. On machine B, I can echo all topics.

jgauthier gravatar image jgauthier  ( 2022-01-10 10:31:04 -0500 )edit

do you use different namespaces? if so you have to add that namespace in front of the topic. If not I agree that the problem is mist likely with your ROS_HOSTNAME ROS_MASTER_URI ROS_IP setup.

crnewton gravatar image crnewton  ( 2022-01-15 05:43:32 -0500 )edit

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Asked: 2022-01-09 13:43:06 -0500

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Last updated: Jan 10 '22