You may be able to modify an old Time Commander from JDS Technologies
(jdstechnologies.com). I don't think they manufacturer the Time Commander
anymore, however, it is an X-10 based PLC and contains dry contacts that
will perform an action based upon a contact closure (float switch). In
stock form it sends an X-10 signal to a module that initiates the action
(start the pump). I've used it to perform other actions when the doorbell
button is pushed. Although not web based, there is software from
Homeseer.com that allows web based control. Might check ebay and such for
the actual unit. I have an old Time Commander Plus around somewhere (it
includes analog-digital inputs). Even if you can't figure out web based
control, it would at least not carry current if you have to hard wire it.
You could probably pick one up fairly cheap.
Hope this helps.
Gordie
----- Original Message -----
From: <eric@megageek.com>
To: <shop-talk@Autox.Team.Net>
Sent: Sunday, January 03, 2010 12:08 AM
Subject: [Shop-talk] Web based PLC
> Ok, I'm looking for a little help here. It might be a little off topic
> for Shop talk, but I know we have the expertise here to answer this.
>
> What I need is a web based logic board for dry contacts. Let me
> explain...
>
> In the new Mansion we are moving into, there is a water tank on the roof
> (5 stories up.) The pump is in the ground. Local wiring code in
> Afghanistan is nonexistence.
>
> I need a safe way for the two float switches in the tank (one for "low"
> and one for "full") to talk to the pump to turn it on.
>
> I don't want to have a 220v line run from the pump, up the 5 stories to
> the roof of the building. So I was thinking that I could put a network
> PLC device up near the tank and another one near the pump. I could log
> into the device via a web interface and program it to turn the pump on and
> off based on the position of the contacts in the float switch.
>
> This is simple in theory, and I'm sure there are devices out there. My
> only problem is that I have a very slow internet connection here and
> surfing for this stuff is very frustrating and isn't yielding results.
>
> So, anyone know where to get these devices? (I'm sure that I'll need two,
> one for the tank and one for the pump.) Also, I'm not adverse to buying
> something and modify it to work the way I need it to if that is my only
> option.
>
> Thanks for the help!
>
> (As for cost, it's not too much of a factor, but if it gets too expensive,
> I have to get approval from the contract manager and I'd like to avoid
> that.) Thanks again!
>
> Oh yeah, the local answer to this problem is "have two people whose job is
> to keep it full. One to stand on the roof and watch the tank and another
> one to turn on and off the pump." You have to love countries where labor
> is cheap.
>
> Moose
> "Be as beneficent as the sun or the sea, but if your rights as a rational
> being are trenched on, die on the first inch of your territory." Ralph
> Waldo Emerson
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