(Changed the tag to EE, since it really is EE...)

Buehler, Martin wrote:

> so i had the idea to use a pc network card with wake-up-on-lan
> functionality to control a relais, turning on the printer. 
> 
> i have no idea if this really works, as i don't know how to connect such
> a network card. will this work when just supplying 5v to it's wol
> connector, or does it really have to sit in a pci slot? 
> 
> as far as i remember, calling the card's mac address rises the wol
> signal, so this would work to control the power relais. but does the wol
> signal stay high forever then? how can i turn the wol signal off again? 

I don't think there's a "shut down on LAN" command. I guess the idea is
that after you turned the device on, it's working and you can communicate
with it using normal network packets. So shutting it down would happen
through some kind of network command (like remote control of a computer,
for example). In this case of course one would need a network client at the
location, in which case you wouldn't need WOL for your application. Maybe
your printer has a shutdown command that can be sent over the network.

I had a quick look around, and it seems that hard facts are hard to get
by...

I started with http://www.google.com/search?q=wake+on+lan+network+card+wol:

- http://www.annoyances.org/exec/show/article04-101: something about
Windows configuration to make it work, and a few discussions of problems.
Leads to
- http://ahh.sourceforge.net/wol/: A WOL client that sends the "magic"
packet. Unluckily the link to the AMD site where their documentation is
supposed to be (or was) only goes to a page that says to contact their
sales people... :(
- http://www.codeproject.com/useritems/WOL.asp: Here's a bit of info about
the actual packets, plus source for another client.
- http://www.depicus.com/wake-on-lan/what-is-wake-on-lan.aspx: Another
description, including a network trace of a WOL packet. This article says
that some cards need a flag to be set for WOL to work, which indicates that
a simple solution like what you're thinking of may work with some cards and
not with others.

This all is more about the network interface than about the NIC interface.
Maybe searching for WOL or "wake on LAN" on the IBM and AMD sites turns up
more info. It seems that both companies claim to have invented it.

OTOH, have you considered a simple remote power switch, like X-10 or so? It
seems that for less than $40 you can get a switched outlet and a remote
control.

Gerhard
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