Subscriber gets no messages

asked 2011-08-05 09:16:45 -0500

427 ●31 ●42 ●51

Hi,

I am almost going crazy ... I analyse a bag file and monitor a strange behaviour. When I use the code below I have to comment one of rospy.Subscriber(...) lines. Otherwise the Program gets no message and rxgraph shows no connection. But with only one subscriber (regardless of which) the code works well!

What is wrong in my idea?

Best wishes from Germany Enjoy the weekend

Poseidonius

import roslib; roslib.load_manifest('Localization')
import rospy
from std_msgs.msg import Float32

def callback(event, index):
     print index

rospy.init_node('OdoMapper')
rospy.Subscriber("/OdoLeft", Float32, callback, 0) # one of them have to be commented
rospy.Subscriber("/OdoRight", Float32, callback, 1)  
rospy.spin()

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Comments

Can you add the output of roswtf to your question?

tfoote ( 2011-08-06 10:29:49 -0500 )edit

Strange - on a Ubuntu PC the code works fine, just my Fedora presents the mentioned behaviour

Poseidonius ( 2011-08-08 06:22:32 -0500 )edit

Strange, indeed. Although I don't use Fedora, I would assume that it is not Fedora itself, but the system setup. Can you check the network setup tfoote posted below even on the local machine?

dornhege ( 2011-08-08 10:35:18 -0500 )edit

Another test, just to verify: Does this only happen on the bag file? If you do 2x rostopic pub, does everything work OK?

dornhege ( 2011-08-08 10:36:54 -0500 )edit

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answered 2011-09-02 10:55:01 -0500

kwc
12244 ●54 ●90 ●132 http://kwc.org/

no activity in a month, closing

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answered 2011-08-05 12:11:55 -0500

dornhege

31395 ●134 ●284 ●498

I'm not sure, what's going on, but for me it works. The only thing I added was the #! line, but that doesn't cause this behavior.

I tested it with 2x rostopic pub. Perhaps that is something you should do for comparison as the script seems to work.

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answered 2011-08-08 08:32:52 -0500

tfoote

58457 ●128 ●550 ●526 http://www.ros.org/

Are you running in a multi computer environment? If so can you check your network setup

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answered 2011-08-06 20:10:56 -0500

Poseidonius

427 ●31 ●42 ●51

updated 2011-08-06 20:28:17 -0500

Hi,

according to the question of @tfoote I made a roswtf ... you are right, something is wrong with the Odo Channels. How can I isolate the problem? I am using ros diamond on a Fedora 14 PC, I take a bag file produced on another PC, start "rosbag play" and the small script above.

Thanks for your effort!

Loaded plugin tf.tfwtf
Package: Localization
================================================================================
Static checks summary:

Found 1 warning(s).
Warnings are things that may be just fine, but are sometimes at fault

WARNING The following stack.xml file list invalid dependencies:
* /home/eos/workspace/SmartX/stack.xml (image_common appears to be an unnecessary depend)
* /home/eos/workspace/SmartX/stack.xml (robot_model appears to be an unnecessary depend)
* /home/eos/workspace/SmartX/stack.xml (visualization_common appears to be an unnecessary depend)
* /home/eos/workspace/ros/ccny_vision/stack.xml (visualization_common appears to be an unnecessary depend)


================================================================================
Beginning tests of your ROS graph. These may take awhile...
analyzing graph...
... done analyzing graph
running graph rules...
... done running graph rules

Online checks summary:

WARNING The following nodes are unexpectedly connected:
* /rosbag->/rosout (/rosout)
* /odomapper->/rosout (/rosout)

Found 4 error(s).

ERROR Communication with [/rosbag] raised an error: 
ERROR Communication with [/odomapper] raised an error: 
ERROR The following nodes should be connected but aren't:
* /rosbag->/odomapper (/OdoRight)
* /rosbag->/odomapper (/OdoLeft)