The UPS Howto: What to do when you're really stuck 7. What to do when you're really stuckHere's a novel solution to UPS control for when the UPS and the computer just aren't on speaking terms. I must say that every time I read this, I'm struck by how clever a solution it is. From: " Raymond A. Ingles" <[e-mail]> To: [e-mail] Subject: UPS HOWTO tip Date: Mon, 24 Feb 1997 11:48:32 -0500 (EST) I don't know if others would find this useful, but I thought I might pass this along for possible inclusion in the HOWTO. Thanks for maintaining a HOWTO that I found very useful! ----------------- My fiancee bought me a UPS as a present, a Tripp-Lite 400, I believe. It was very welcome and seems to operate as expected, but unfortunately doesn't have a serial interface to let the computer know the line power has failed. It's apparently intended for home or office use where the computer will not be left unattended. This, of course, was unacceptable and I began working on a line monitor, planning on opening up the case and figuring out how to add the hardware that the manufacturer had left out. Then I realized that there was a quicker and simpler and cheaper (if somewhat less functional) way. I had an old 2400 baud modem that I wasn't using, and hooked it up to an unused serial port on my computer. I then plugged the modem into a surge supressor plugged into the wall power. I set up powerd with the options as follows: ----- serialline /dev/ttyS1 monitor DCD failwhen low ----- Now, when the wall power fails (or, since that hasn't happened lately, when I pull the surge supressor from the wall to test this setup) the modem fails but the UPS starts supplying power to the computer. When powerd notices the modem has dropped DCD, it triggers the powerfail sequence. Obviously, this has some limitations. You can't tell from the modem when the battery is low and so on. You can only tell that the wall power has failed. Still, it's certainly cheap and I hate to see functioning computer equipment lie unused. These days you should be able to get a 2400 baud modem for very nearly free. I'd still suggest getting a real UPS with full communication capability. But if you're stuck with a less-functional one, this may at least make it useful. Sincerely, Ray Ingles [phone] [e-mail] "Anybody who has ever seen a photograph showing the kind of damage that a trout traveling that fast can inflict on the human skull knows that such photographs are very valuable. I paid $20 for mine." - Dave Barry S