Re: Connecting pc to real world

[nobody@xxxxxxxxxxxx (Dave Houston)]

USB is rather limited as far as distance. After about 12' you need a
repeater.

Your best bet is serial. I would recommend converting the serial to RS485.
You can then find lots of devices that can daisy-chain on the RS485 bus.
There are also ways to expand a single RS232 port to handle a lot of I/O. A
few places to visit to get an idea of what's available...

     http://www.bb-elec.com/
     http://www.eeci.com/
     http://www.weedtech.com/

Have you considered using TCP/IP?

"Paul in Redland" <paulinredland@xxxxxxx> wrote:

>I'm in the early stages of planning a HA system for a house we're going to
>build in about 2 years. I'm  a DIY kinda guy and am planning to use a
>touchscreen pc to control security, heating/cooling, solar water heating,
>landscape watering etc. We're not real big on audio/video, so probably won't
>have any of that integrated into the system. Writing the code to control
>everything is within my abilities.  My question is how does the pc
>communicate with the real world. The touch screen that I'll be using has a
>USB port and a serial port. How exactly do I connect the various sensors,
>both contact closure and analog to the pc and how do I connect the pc to the
>various pumps, valves and external systems to be controlled? I presume some
>sort of I/O device that plugs into either the serial or USB port and
>provides X number of 'channels', but I've googled around and haven't come up
>with anything. I'm looking at perhaps 100 input and half that number of
>output channels. How do you guys do it?
>TIA
>Paul
>