I think your schematic looks OK but I don't have the data sheet
handy for this part.
You need to look at how other 2 wire setups work because you are unlikely
to find someone that has this particular part with coded.
The usual reason for using a separate A/D is for more resolution.
The ground layout is important or you'll be measuring the ground
voltage drop every time you turn on a relay or LED.
Dwight