At Sun, 14 Jun 2026 14:48:50 -0400 Eben King <[email protected]> wrote: > > On 6/14/26 12:39, Robert Heller wrote: > > At Sun, 14 Jun 2026 10:13:32 -0400 Eben King <[email protected]> wrote: > > > >> > >> On 6/14/26 10:07, John Hasler wrote: > >>> Before you replace it open it up and reseat and retighten all the > >>> connections (especially the battery terminals). > >> > >> Did that. I disconnected them all, checked the battery voltages (13.4 > >> and something else reasonable), and checked the 60A fuse between them. > >> It's a weird fault, that it goes instantly from completely normal to bad. > > > > Does it still work as a "dumb" UPS? > > You know, I haven't checked that. I would just need to unplug the USB > and reboot the UPS, correct? > > > If so, one possible temp solution is to > > get an "old" dialup modem. > > I actually do have two external modems, one 14.4 and one 33.6. I'm > fairly sure that at least one of them works. Just gotta find them... > > > Plug the modem's power brick into the *mains*, and > > connect the modem's TTY connection to a RS232 <=USB adapter and then you can > > get powerd and have it monitor the ModemReady signal. > > Wait, I'm not clear on the connections. > > UPS -> modem through RS-232
No, the modem is NOT plugged into the UPS, it is pluged into the wall (house/building mains). The modem is NOT on the UPS. The idea is that when there is a power failure, the modem goes off. While there is power to the modem it asserts its "ModemReady" (DSR, pin 6 on the 25-pin or pin 6 on the 9-pin connector: ioctl's TIOCMGET command, then bit TIOCM_DSR [man ioctl_tty(2)]). > then what does powerd do? powerd is an (old) package that contains a general purpose deamon that can be configured to test something, such as a RS232 signal line and if the signal changes to a specificed state initiates a system shutdown (invokes "/sbin/shutdown -h <some time delay>"). I don't know if it still exists. > > The modem will assert > > ModemReady so long as it has power. ModemReady will drop when there is a > > power > > failure. (I suspect that this is probably not really a viable option. > > Yeah. If it just tells me when there's a power failure, the beeping > would tell me. Unless you're saying that powerd could kick off processes? > Yes. ACPUPSD does this. > > These days are probably rare and PCs no longer have RS232 ports...) > > I might have to use a USB -> RS232 adapter. The previous UPS had only > regular serial and I used one of those, and when the boot procedure > initted the USB ports it sent something down the serial cable (BREAK?) > which caused the UPS to power off. Not ideal. APC's "SmartUPS" communicate over the RS232 (older models) or USB (current models) a whole host of information about the UPS to the computer. The acpupsd package understands that communication and does various things, like broadcast messages about power failures and communication issues with the UPS, etc. The acpupsd daemon will also start a computer suchdown if the UPS indicates a power failure. The acpupsd daemon will also act as a "server" to allow other computers on the UPS to know about the power failure so that "slave" acpupsd daemons can shutdown other computers that share the UPS. > > > -- Robert Heller -- Cell: 413-658-7953 GV: 978-633-5364 Deepwoods Software -- Custom Software Services http://www.deepsoft.com/ -- Linux Administration Services [email protected] -- Webhosting Services
