OK, after som minor digging I found the answer, BUT there is a better way, look at akbooer?s reply below!
First of all, find the Device XML File. In my case that is: D_NorthQWatts.xml
How do I konw that? Looked at the created device and under advanced, params there is a value, device_file, who Points you towards that name.
Then you have to find the impelementation file, in my case I_NorthWatts.xml, here i did a wild guess, but after browsing the existin luup-files ( APPS → Develop Apps → Luup Files
i guess that the implementationfile is following the pattern, replace D with I on device xml file… =)
After that, you go to: APPS → Develop APPS → Create device
Type in the XML-filenames. And create.
Now, you Think there is a device ready for you, but no, you have to reload Luup first… APPS → Develop APPS → Serial Port Confguration → Klick Reloaf LUUP.
Wait a couple of moments and go to devices and manage your device…
A note! Create the devices one at a time, and give them a name Before creating a new one since they would be namned Unknon device so if you add two without renaming you will only get one in the end…
This thread, below, pointed me towards this solution. Thank You TommyE ( http://forum.micasaverde.com/index.php?action=profile;u=16879 )
http://forum.micasaverde.com/index.php?action=dlattach;topic=34900.0;attach=27602;image