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asked 2012-06-12 17:26:40 -0500

punching gravatar image

updated 2012-06-14 18:41:30 -0500

First ROS script, jumping into the deep end. I have an Arduino publishing data (it's working fine) to a topic called Adc. I'm trying to write a Subscriber to read that data and eventually write it to a CSV file.

It compiles ok with no errors but shows nothing. The data types that are published are 5 different uint16s but when I tried "from std_msgs.msg import uint16) and then use uint16 below I get an error so I went back to String in the sample code.

Am I on the right track here?

#!/usr/bin/env python
import roslib; roslib.load_manifest('sensorcsv')
import rospy
from std_msgs.msg import String
def callback(data):
    rospy.loginfo(rospy.get_name()+"I heard %s",data.data)
    print rospy.get_name()+"I heard %s",data.data

def listener():
    rospy.init_node('listener', anonymous=True)
    rospy.Subscriber("Adc", String, callback)
    rospy.spin()

if __name__ == '__main__':<br>
    listener()
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answered 2012-06-14 21:05:25 -0500

punching gravatar image

Figured it out. For those that might run into this to.

This video helped explain it to me. http://vimeo.com/24616666

import roslib; roslib.load_manifest('sensorcsv')
import rospy
 # from rosserial_arduino import adc
from std_msgs.msg import UInt16
from rosserial_arduino.msg import Adc

def callback(data):
    print "Callback"
    print data.adc0, data.adc1, data.adc2, data.adc3, data.adc4, data.adc5
#    print rospy.get_name()+': ' + str(data.data)

def listener():
    print "listener"
    rospy.init_node('listener')
    rospy.Subscriber("adc", Adc, callback)
    print "rospy.subscriber"
    rospy.spin()
    print "rospy.spin()"

if __name__ == '__main__':
    print "Main"
    listener()
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Comments

Can you please update your original post instead of those four different answers. It helps people understand what is going on.

dornhege gravatar imagedornhege ( 2012-06-15 01:15:17 -0500 )edit
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answered 2012-06-12 22:08:05 -0500

Lorenz gravatar image

If you publish messages of type UInt16, subscribing with a string will just not work. ROS is strict on message data types. According to your question, you tried to import the data type uint16 which does not exist in std_msgs. The correct type is UInt16. Try:

from std_msgs.msg import UInt16

and change the line that creates the subscriber to:

rospy.Subscriber('Adc', UInt16, callback)
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answered 2012-06-14 13:36:04 -0500

punching gravatar image

http://www.ros.org/wiki/rosserial_arduino/Tutorials/Arduino%20Oscilloscope

It is a custom message. I've tried to import into my script every combination of

from rosserial_arduino import Adc from rosserial_arduino.msg import Adc from Adc.msg import adc

etc. Everytime it says the module isn't found.

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answered 2012-06-14 13:06:16 -0500

punching gravatar image

I'm getting closer.

Now when I try to connect the publisher script shows this. The publisher is publishing 6 UInt16 variables, is the problem that I'm only subscribing to one of them? Or is the topic type not really UInt16 but a new type made up of 6 UInt16s?

[WARN] [WallTime: 1339714526.664093] Could not process inbound connection: topic types do not match: [std_msgs/UInt16] vs. [rosserial_arduino/Adc]{'message_definition': 'uint16 data\n\n', 'callerid': '/listener', 'tcp_nodelay': '0', 'md5sum': '1df79edf208b629fe6b81923a544552d', 'topic': '/adc', 'type': 'std_msgs/UInt16'}

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answered 2012-06-13 08:24:10 -0500

punching gravatar image

updated 2012-06-13 08:24:53 -0500

I think I put in Uint16 not UInt16 yesterday when I tried this. I fixed it and it compiled but same result.

I put some print commands in so I can see what commands are being executed.

The results of running this is

Main
listener
rospy.subscriber()
when I Ctrl-C it shows
rospy.spin()

Looks like the callback function isn't being called.

#!/usr/bin/env python
import roslib; roslib.load_manifest('sensorcsv')
import rospy

from std_msgs.msg import UInt16
def callback(data):
    print "Callback"
    rospy.loginfo(rospy.get_name()+"I heard %s",data.data)
    print rospy.get_name()+"I heard %s"+data.data

def listener():
    print "listener"
    rospy.init_node('listener', anonymous=True)
    rospy.Subscriber("Adc", UInt16, callback)
    rospy.spin()
    print "rospy.spin()"

if __name__ == '__main__':
    print "Main"
    listener()
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Asked: 2012-06-12 17:26:40 -0500

Seen: 2,710 times

Last updated: Jun 14 '12