Seems that I have missed your post @CirruZZ. Sorry for that. I do have ser2net running in rpi2 where my heat pump is connected to gpio pins tx/rx/gnd/3.3v with two optocouplers. Heres how it’s wired http://rago600.sourceforge.net/generic_com.gif. Right now I have all the components on a breadboard as “prototype” but as soon as I find the time I’ll do some soldering and put it in a box.
Here’s a guide to set up ser2net Share Z-wave dongle over IP (USB over IP using ser2net / socat ) guide (Don’t mind about the socat part)