Thanks for the reply, yeah so the device I am using is the Aeotec Smart Switch 6. I was trying to get the device to read voltage and current as the default handler does not support this even though the device supports it.
I found a custom device handler for the device written by @Robert_Vandervoort here . Created a new device handler in the IDE and published it for myself. I then assigned the device handler to an already connected Aeotec Z-Wave plug. The only measurements that worked where energy and power so I will have to investigate that further.
Why do you say there isn’t much point in doing this for hub connected devices if the classic way of doing things is going to be turned off? Shouldn’t everyone be doing this for there custom device handlers for hub connected devices?