MD5 error for feedback_states topic

Question

Hi all,

I receive the following error:

[WARN] [WallTime: 1401915353.147587] Could not process inbound connection: Client [/rostopic_4474_1401915352624] wants topic [/feedback_states] to have datatype/md5sum [control_msgs/FollowJointTrajectoryFeedback/10817c60c2486ef6b33e97dcd87f4474], but our version has [control_msgs/FollowJointTrajectoryFeedback/b11d532a92ee589417fdd76559eb1d9e] Dropping connection.{'message_definition': '# ====== DO NOT MODIFY! AUTOGENERATED FROM AN ACTION DEFINITION ======\nHeader header\nstring[] joint_names\ntrajectory_msgs/JointTrajectoryPoint desired\ntrajectory_msgs/JointTrajectoryPoint actual\ntrajectory_msgs/JointTrajectoryPoint error\n\n\n================================================================================\nMSG: std_msgs/Header\n# Standard metadata for higher-level stamped data types.\n# This is generally used to communicate timestamped data \n# in a particular coordinate frame.\n# \n# sequence ID: consecutively increasing ID \nuint32 seq\n#Two-integer timestamp that is expressed as:\n# * stamp.secs: seconds (stamp_secs) since epoch\n# * stamp.nsecs: nanoseconds since stamp_secs\n# time-handling sugar is provided by the client library\ntime stamp\n#Frame this data is associated with\n# 0: no frame\n# 1: global frame\nstring frame_id\n\n================================================================================\nMSG: trajectory_msgs/JointTrajectoryPoint\n# Each trajectory point specifies either positions[, velocities[, accelerations]]\n# or positions[, effort] for the trajectory to be executed.\n# All specified values are in the same order as the joint names in JointTrajectory.msg\n\nfloat64[] positions\nfloat64[] velocities\nfloat64[] accelerations\nfloat64[] effort\nduration time_from_start\n\n', 'callerid': '/rostopic_4474_1401915352624', 'tcp_nodelay': '0', 'md5sum': '10817c60c2486ef6b33e97dcd87f4474', 'topic': '/feedback_states', 'type': 'control_msgs/FollowJointTrajectoryFeedback'}

I have a machine publishing on the feedback_states topic using the code shown below. The error is raised when, on another machine, i run rostopic echo "feedback_states". The publisher is Groovy whist the receiver is Hydro.

Code to publish on feedback_states:

b_msg = FollowJointTrajectoryFeedback()
time = rospy.Time.now()
fb_msg.header.stamp = time
fb_msg.joint_names = 'j_wrist1_arm1'
fb_msg.actual.positions = val
pub_fb_state.publish(fb_msg)

My initial thinking is that perhaps there is an issue with the different distributions for the control_msgs. If this is the case or not i have no idea how to resolve this. Should i update the Groovy version to Hydro?

Any help is appreciated it.

Regards.

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Originally posted by anonymous8676 on ROS Answers with karma: 327 on 2014-06-04

Post score: 0

Answer 1

The publisher is Groovy whist the receiver is Hydro.

While I don't really see any changes to the control_msgs package between groovy and hydro (see control_msgs/compare/groovy-devel...hydro-devel), it could well be that the MD5 of the individual messages has changed, due to changes to the code generation. That would explain the error you are seeing.

Try again with a Groovy - Groovy, or Hydro - Hydro combination and see if that resolves your error (I'm betting it will).

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Originally posted by gvdhoorn with karma: 86574 on 2014-06-05

This answer was ACCEPTED on the original site

Post score: 1

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Original comments

Comment by anonymous8676 on 2014-06-13:
Correct, the issue was that there were two different versions being used. I ended up making both Hydro and the messages worked.

Thanks for your help.