Why my publisher node stops when subscriber node start?

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Hi all,

I currently working on creating a GPR system based on Walabot sensor. The data that I want to publish is the raw signal from Walabot which consist of two-row array of amplitude and timeaxis value with 4096 columns for each row. Hence, using float32multiarray i was hoping that i could send the array over to subscriber node for signal processing. I followed the normal procedure of roscore -> publisher -> subscriber.

As soon as I turn on subscriber, my publisher immediately stops. The frustrating part is both terminal of publisher and subscriber didn't print out want error that has happened which leads to more confusion.

I have tested the way is publish and subscribe to Float32MultiArray message type using simple array. The way I did work but when I do the complicated node is does not work. I included my simple publisher and subscriber that use Float32MultiArray as message type.

Here is video of my problem

Hope anyone could help in this. Thank you!

This is my publisher node.

#!/usr/bin/env python
from __future__ import print_function  # WalabotAPI works on both Python 2 an 3.
from sys import platform
from os import system
from imp import load_source
from os.path import join
import rospy
from std_msgs.msg import Float32MultiArray


modulePath = join('/usr', 'share', 'walabot', 'python', 'WalabotAPI.py')
wlbt = load_source('WalabotAPI', modulePath)

wlbt.Init()

def DataCollect():
    # wlbt.SetArenaX - input parameters
    xArenaMin, xArenaMax, xArenaRes = -10, 10, 0.5
    # wlbt.SetArenaY - input parameters
    yArenaMin, yArenaMax, yArenaRes = -10, 10, 0.5
    # wlbt.SetArenaZ - input parameters
    zArenaMin, zArenaMax, zArenaRes = 5, 11, 0.5

    # Initializes walabot lib
    wlbt.SetSettingsFolder()

    # Establish a connection between the Walabot and the computer
    wlbt.ConnectAny()

    # Set sensor profile
    wlbt.SetProfile(wlbt.PROF_SHORT_RANGE_IMAGING)
    # Set arena by Cartesian coordinates, with arena resolution
    wlbt.SetArenaX(xArenaMin, xArenaMax, xArenaRes)
    wlbt.SetArenaY(yArenaMin, yArenaMax, yArenaRes)
    wlbt.SetArenaZ(zArenaMin, zArenaMax, zArenaRes)
    wlbt.SetThreshold(50)

    # Set filtering to none
    wlbt.SetDynamicImageFilter(wlbt.FILTER_TYPE_NONE)

    pair = wlbt.GetAntennaPairs()

    # Start the Walabot device
    wlbt.Start()

    pub = rospy.Publisher('rawSignal', Float32MultiArray, queue_size=1000)
    rospy.init_node('walabotRawSignal', anonymous=False)


    while not rospy.is_shutdown():
        rospy.sleep(2.0)
        try:
            wlbt.Trigger()
            targets = wlbt.GetSignal((pair[4]))
            rawSignalArray = Float32MultiArray(data=targets)
            pub.publish(rawSignalArray)
            rospy.loginfo(rawSignalArray)
        except rospy.ROSInterruptException:
            pass

    wlbt.Stop()
    wlbt.Disconnect()
    print("Terminate successfully")

if __name__ == '__main__':
    DataCollect()

This is my subscriber node:

#!/usr/bin/env python
import rospy
from std_msgs.msg import Float32MultiArray

def callback(data):
    rospy.loginfo(data.data)

def processRawSignal():
    rospy.init_node('processRawSignal', anonymous=True)
    rospy.Subscriber("rawSignal", Float32MultiArray, callback)
    rospy.spin()

if __name__ == '__main__':
    processRawSignal()

My simple testing of using Float32MultiArray message in Publisher and Subscriber Publisher:

#!/usr/bin/env python

import rospy
from std_msgs.msg import Float32MultiArray

def talker():
    pub = rospy.Publisher('chatter', Float32MultiArray, queue_size=1000)
    rospy.init_node('talker', anonymous=True)
    rate = rospy.Rate(10) # 10hz
    while not rospy.is_shutdown():
        hello_str = [1,2,3,4,5]
        array = Float32MultiArray(data=hello_str)
        rospy.loginfo(array)
        pub.publish(array)
        rate.sleep()

if __name__ == '__main__':
    try:
        talker()
    except rospy.ROSInterruptException:
        pass

Subscriber:

#!/usr/bin/env python
import ...