Matlab can't receive Topic from Ros_MasterPC .

Good morning, everyone.

I want to use Matlab on Windows10 and Ros on Ubuntu18.04 to exchange data with each other.

I can send Topic using rospublisher, but I cannot receive Topic (chatter2) properly using rossubscriber.

Please solve this problem.

Ros side

Terminal1

$ export ROS_IP=192.168.**. **

$ roscore

Terminal2

$ rosrun *** pub_matlab.py

< pub_matlab.py >

#! /usr/bin/env python

import rospy

from std_msgs.msg import String

def talker():

pub = rospy.Publisher('chatter2', String, queue_size=10)

rospy.init_node('Pub_matlab', anonymous=False)

rate = rospy.Rate(10) # 10hz

while not rospy.is_shutdown():

hello_str = 'Hello'

rospy.loginfo(hello_str)

pub.publish(hello_str)

rate.sleep()

if __name__ == '__main__':

try:

talker()

except rospy.ROSInterruptException:

pass

Matlab side

>>rosinit('http://192.168.**. **:11311','NodeName','/matlab')

>>sub = rossubscriber("/chatter2", "std_msgs/String")

>>sub =

Subscriber property:

TopicName: '/chatter2'

LatestMessage: [0 x 1 String].

MessageType: 'std_msgs/String'

BufferSize: 1

NewMessageFcn: []

>> rostopic list

/chatter2

/rosout

/rosout_agg

/statistics

/tf

>> rostopic info /chatter2

Type: std_msgs/String

Publisher:

* /Pub_matlab (http://*****-19115N-CLR:******/)

Subscriber:

* /matlab (http://192.168.**. **:*****/)

>> rosnode ping Pub_matlab

Sends a ping to the Pub_matlab node with a timeout of 3 seconds.

No ping response.

No ping response.

No ping response.

No ping response.

Average ping response time: NaN milliseconds

Answer 1

[Cam Salzberger]

Hello Shogo,

This is probably the most common ROS communication issue I've seen. Usually the issue is that ROS_IP is not set in the terminal that you create the non-MATLAB publisher on. That seems to be the case here.

See this answer for more information.

-Cam