Take a look at the information in this 
ART SmartTrack post and try a simple Vizard script to test the connection:
	Code:
	import viz
viz.go()
# VRPN Tracker connection (to ART Dtrack)
vrpn = viz.add('vrpn7.dle')
headTracker = vrpn.addTracker('DTrack@localhost')         #Default sensor is 0
flystickTracker = vrpn.addTracker('DTrack@localhost',1)   #Try index 1 or 2 here
flystickButtons = vrpn.addButton('DTrack@localhost')      #Flystick buttons
flystickJoystick = vrpn.addAnalog('DTrack@localhost')     #Flystick analog thumb joystick