Re: Connecting pc to real world

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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?

One way is to use cat.5 ethernet cable or telephone cable then connect
many mcu's in a one-wire communication in a open-collector setup. Use spare
pair for power.