I did not managed to get i working, shifted to a Raspberry PI, that works perfect - It seems that I also get version 1.x data from the gateway, Interesting if the gateway both can receive 1.x and 2.x data from sensors.
Couldnt get it to work, so the gas and powermeters where replaced after a call to the Energy company. The new P1 smartmeters is connected with usb to Domoticz and works like a charm!
Topic can be closed.
I have found a workaround by sending the heartbeat message as a separate V_MULTIMETER child. This then gives me a voltage reading of 0V every 30 seconds that I can use with the Domoticz last update feature
Would like to hear any better ways of doing this.