Is there a 485 module for Arduino, ive googled and it appears as though there is?
You want someone to confirm the results of your web search? There are lots of threads and articles on it already. Try going to the Arduino Wiki
and use the search there for starters. 'Module' could be taken to mean 'shield' or 'library'. You probably want both, and in the case of a library, I assume something like modbus or DMX. (I know nothing about these, they could even be the same thing, I just found them in a search.)
And would this let me just look at registry address, i assume i would program locations them in the software?
If, by 'registry address', you mean that you would write a sketch where you store your measurements in an array, and also retrieve them in response to query on the comm interface, then this sounds absolutely fine to me.