Re: Controlling Valves/Relays from PC

[Buck <kc2hiz@xxxxxxxxx>]

Walden H. Leverich wrote:

> I'm looking to do a pet-project where I want to control the flow of
> water via a PC. I need fast on/off, and I need to control ~200 different
> valves. We're trying to produce something like
> http://www.youtube.com/watch?v=Z2LUz2WVcek for a prom. Any ideas on a
> device capable of the control? I have no problem doing the programming,
> but I need something that will give me the ability to control that many
> devices.
>
> Ideally this would be a simple UDP attached controller that took a 24
> byte packet and set the on/off status of each of the switches based on
> the bit value in the packet.

Cool project.

I presume you are going to have one pump pressurise the line and have
all the valves simply cycle on/off.  I understand your preference for
TCP/IP - these relay control boards may help:

http://www.datanab.com/solutions/BarioNetWebRelay.htm?gclid=CNeruceXzZYCFQQrFQodhRXnyw
http://www.controlbyweb.com/webrelay-10/index.html
http://www.controlanything.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=NER325ProXR&Category_Code=CAT_RELAY32_ETHERNET
http://www.6bit.com/products/smartrelayE.php?products_id=33

Almost certainly, the mechanical action of the valves is going to be
your bottleneck when it comes to speed.  The trade-off is often that a
high speed valve needs more current to open/close.  That drives the
relay selection.  Another consideration is whether the valves are
self-closing or if they require a pair of relays - open and close.  You
might be able to use return springs to construct your own self-closing
valves but then the valve motor will take more current to operate the valve.

  --buck