I'm toying with an idea of a web server in a RS485 cable. Basically, few modern computers have serial ports, but everyone has an ethernet port.
My idea is to build a RS485 to Ethernet "cable" with an arduino interpreting the messages on the RS485 bus and populating a web page with them. This is not a general purpose web server; it's a very specific and limited web server.
I need to serve up four pages, two are static and two are input forms with 6-8 field each, and download a spreadsheet in CSV format. I have a sketch that does all this on an LCD screen; now I'm looking to interface it to a laptop or tablet.
The "cable" would have to have act DHCP master if a computer is plugged in. It would be ideal (and very cool) if it had a wifi AP interface as well as wired.
Is anyone aware of anything like this? I'm not really that familiar with the arduino universe; most of my embedded background is in custom systems and OpenWRT, and nothing like what I"m thinking. In that world, this would be handled by lighttpd+php and dnsmasq, but there's no room in an arduino for that.
I don't want to use USB, because that would require custom software on each and every platform, and my target audience uses everything from Android to Mac.