Thanks for the responses. I just goggled and read up on the RS232 serial 9-pin plugs and configurations. Looks like I am just using a nulmodem configuration so really only using two of the communication pins and the others are just open.
I just purchased one 4 pin unit with the built in areal as recommended on ebay for $7 delivered. Cheaper than the just the 10m cat5 cable
The distance from the inverter/battery room to the house - laundry-utility room is only 3m and i plan to just use my wifes small notebook that has built in Bluetooth to fetch data from that room.
It will be great to be able to keep check on the system from the comfort of the house rather than having to go outside in the rain,dark,cold fiddling with cabinet keys and serial cables
i will be able to remotely start the generator over Bluetooth from the laptop in my workshop when I have a huge load like 10kw plasma cutter with a 2.5kw air comp running at the same time.
I will post back with how i get on making it work once I have it in hand .