[Nut-upsdev] Powercom RS232 driver improvement/rewrite

Peter acidoborico at gmail.com
Wed Mar 24 03:55:08 UTC 2010

Hello all,

Last week I rescued and UPS from the trash (it's really amazing the
kind of things you can find in the trash of the university research
labs). No manual, no cd, no cables, just the unit. It's name is
"Blizzo 500", and blizzo was just the rebranding of a spanish reseller
which has been out of the scene for nearly two years now, at least
according to the wayback machine. Thanksfully, it had some stickers
(in english) with brief instructions, warning about output wave not
being sinusoidal, and standard info about power.

After a quick test, it looked like working, so I carried it home. I
then opened it, and it really looked like a "line interactive" or
"standby" type. After a bit of reverse engineering, I managed to get
the serial port schematic, looking like it supports both "dumb" and
"smart" mode, so I tested it in "dumb" mode, with the genericups
driver. I also added support to override DSR (as I needed it to use
with an "straight" cable, with just two pull-ups to DTR) to NUT 2.2.2,
just to find that the latest version already has it (thats the problem
of using stable debian), so I'm not submiting the patch. After playing
arround with an optocoupler and the single PCI slot of my motherboard,
the computer where I plugged it now supports autoresume without power
races :).

However I was puzzled about the fact that the serial port looked like
"smart", so I tried searching in google images with random searches
about ups until I found something like my unit (at least in shape). It
was a SOLA S1K320, and the chasis really looked like my unit,
excluding power connectors and front panel. I could find the manual,
and saw that the serial port description matched with what I had
reverse engineered. According to the manual, some leds of my units are
only available in the 650VA version, but mine looks like a 500VA. The
manual refered to some "UPSMON" software, which I tracked to Powercom,
just to find out that the KIN or BNT [456]25AP also have the same
chasis design as my unit, but according to this
(http://pcmups.com.tw/download/Download/PCM-King325A-625AP.pdf), mi
ups is nearer the KIN (due to the drawing of the european power
connector). The manuals also match, but not the serial port "details".
As NUT supports both the SOLA and Powercom, I tested both drivers to
finally find that the UPS answers to the Powercom protocol, but only
after modificacions of the check values, thanks to the documentation
of Michael Tokarev.

This process however raised some questions:
Are the SOLA S1KXXX really following the best protocol? They look
quite like the Powercom, including manuals. (ok, this is just

I could find some info of the protocol in the upsd by Michael Tokarev,
and also the recently provided by powercom for the USB models (as it
looks like they are the old ones with a USB to serial chip included),
and looks like the implementation of the driver lacks some features.

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