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Monday, March 26, 2007

Request For Assistance: Remote Power Switching

I'm interested in being able to remotely (i.e. over the Internet) toggle the power connection feeding various AC peripherals, such as an electric blanket or small space heater (which'd be in a nonflammable area for fire safety reasons). I'm a newbie to this particular subject area, so apologies upfront for the elementary nature of this post. My brief perusal of the X10 powerline automation scheme suggests that it's only applicable for within-a-dwelling applications (i.e. behind a common circuit breaker box) although perhaps there's a bridge device available that extends X10 automation to WAN connections.

All the other stuff I've found via Googling about seems to be designed for remote power toggling of servers, with beefy current capability and an equally beefy price tag. What I'm imagining is a small box with a single AC input and one-to-a-few individually controllable AC outputs, fed by a wired or wireless Ethernet connection, and with a password-protected web server running inside that I can control from a WAN-located Mac, PC, etc. browser after opening up necessary firewall holes (thereby implying that it'll need to use standard TCP and/or UDP ports).

Your suggestions are welcome, either privately or (preferably, as I suspect others may have an interest in this) via the comments. Thanks in advance, readers!

Reader Comments

(Add your comments)

at 3/26/2007 10:45:25 AM, M2M Automation said:
m2m-world.blogspot.com/2007/03/remote-control-for-untility-companies.html The company creates and black box that plugs into your asset. The black box has a built in pager that responds to pages that it receives. Based on the page that it received it performs an action - turn of the power supply, turn on the power supply, turn the motor on etc. I am sure they must have built in some sort of security mechanism - could not find any information on that on the website.

at 3/27/2007 8:17:42 AM, Taylor said:
Interesting. Yeah back in the day I remember we used to install the ones you mention that are designed for servers. I am surprised they haven't come down in price - they weren't all that expensive - maybe somewhere around $500 or so? But yeah, for an electric blanket that's probably overkill. Are you building a central media closet - or have another application in mind?

at 3/27/2007 8:23:14 AM, Taylor said:
As for X10 I can tell you my experience with it. Mostly it works, but its slow. Sometimes it doesn't work. There's a plethora of interface options - several manufacturers make nice in-wall light switches for example. This is nice to give a normal tactile interface as well as remote control via remote (use the RF remote) or computer/web. If you want web control you need the CM11A interface, I think it's called, or the firecracker. Eons ago X10 was having firesales on firecrackers + peripherals so I picked up a bunch of this stuff. To date, I haven't found a decent interface program on the computer - the best was MrHouse or something, a kinda of clunky, yet functional, perl cgi implementation (you supply the host).

at 3/28/2007 2:55:00 PM, Howard said:
A Google search yields many suppliers of such devices. They are usually used for rebooting hung servers. There are also kit makers.

at 3/28/2007 5:30:37 PM, Rick said:
Check these out - they work great. digital-loggers.com/EPC.html

at 3/28/2007 6:09:23 PM, TC said:
If you want a fully DIY implementation then just use a "Rabbit". It's a very small and inexpensive development board, it's well documented, and has a built-in wired ethernet port. Just use the DIO to control a 5V or 12V coil AC relay through a transistor. The AC wiring is the easy part. There should already be examples of how to integrate a "micro" web server that runs out of onboard FLASH memory. Like I said, it's well documented, and popular with the budget minded DIY crowd. Just one word of caution...use a dual-pole AC relay and switch both the white neutral and black live wires at the same time (the green earth ground should ALWAYS be connected to the outlets). Your specific application will define the current rating of the relay and the necessary wire gauge (I suspect 12-14AWG). For the AC input just chop the end off of a standard 3-prong power cord. And remember to double check ALL of your wiring before plugging into the wall! AC will kill you long before the main circuit breaker trips so respect it!

at 10/31/2007 4:25:46 AM, Arthur said:
Rick said: Check these out - they work great. digital-loggers.com/EPC.html a BIG "not" here. Our company was enticed into purchasing some of these by the lower price compared to other makers. They have been utter disasters. The original EPC controls we have, are not software-upgradable without return-to-factory plus a healthy portion of their purchase price to get the upgrade. They refuse to exist on the same LAN. Every time one was reset and its IP address entered it would work, but the one of the other four would be unreachable from the Internet. After a long and painful time this was traced down to the systems not having properly implemented the established and understood ARP networking protocol. The new EPC2 with voltage and current monitoring has been even worse. The first versions we got had ARP problems that were even worse than the previous. Instead of not responding to ARP queries for its IP address, they responded to ARP queries for *every host in their network*, and disrupted communications to our servers on the same subnetwork. To top things off, one of their power switches simply began crapping garbage at maximum network rates into our LAN. We lost over $60000 to that single incident returning TOS guarantee money to our customers who could not connect to their servers. The last switch which we purchased simply refuses to connect to the network no matter how reset. No matter what it is connected to, it connects and disconnects from the network at approximately every second. This prevented its use as a backup when another switch suddenly refused to answer networking, and was not discovered until the emergency it was needed for. Evidently Digital Loggers, Inc quality control totally sucks if they couldn''t catch "totally refuses to network". IMHO, the worst and most horrible feature is still present in the EPC2 software. Whenever you use the button that is supposed to reset *only the admin password and networking IP settings* to defaults, believe it or not, it turns all of the freaking servers off! And even if the front panel switches are in the so-called "forced on" position. Customer service? Hah! The switch that was returned because its 15AMP circuit breaker consistently tripped with less than 5 Amperes load on the circuit was returned to us with software upgraded and the same circuit breaker still popping at less than 5 amps. And as far as I can tell from their responses to their controller blowing a whole rack of servers to hell by that "turn off all the power when they try to reset the IP address, even if the switches are all set to forced on", they basically don''t give a damn. Except to assure that at some supposed future time, the serial interface the switch pretends to have will actually be implemented, so that ethernet need not be used.

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