UPS shutdown signalling
horse
(the UPS see's a brownout and tells the client s/w to shutdown the OS)
Problem is, I have four servers that I need to shutdown at the same time,
ie. when the main UPS detects a critical problem.
APC sell a RS232 expander module to drive 3 servers
(and an 8 way version too), but they are quite expensive.
I'd like to know what is inside such a module,
and is it possible to replicate one.
(I'm thinking maybe a chain of RS232 driver chips, or does the
shutdown signal require some handshaking?)
Also, they sell something called a "smart cable" to link the UPS and server
I was told that a normal RS232 lead will not work?
What is in this cable that makes it so "smart" :-)
regards,
h.
mrob...@worldnet.att.net
: I have a UPS made by APC that communicates to the server via RS232
: (the UPS see's a brownout and tells the client s/w to shutdown the OS)
: Problem is, I have four servers that I need to shutdown at the same time,
: ie. when the main UPS detects a critical problem.
: APC sell a RS232 expander module to drive 3 servers
: (and an 8 way version too), but they are quite expensive.
: I'd like to know what is inside such a module,
: and is it possible to replicate one.
: (I'm thinking maybe a chain of RS232 driver chips, or does the
: shutdown signal require some handshaking?)
Some of the earlier versions of this that I'm aware of just used one
of the handshake lines on the RS232 port, for example CTS - Clear
To Send. The UPS asserts CTS when everything is fine and drops it
when things are not fine (power went out). The software is just
looking at the CTS signal once a second or so, and if the signal goes
away, it does something appropriate to the OS (simulates Alt-F4 for
Windoze; 'shutdown -h now' for Linux, etc).
Newer UPSs might actually do some communicating between the UPS and
the host software...it might be useful to pass a 'time remaining'
value or something in ASCII, as well as perhaps initiate UPS testing
(when the line power is OK) from software.
Some UPSes even supply a relay contact closure on operation. They
just open or close a set of contacts when the UPS kicks in due to
line power loss. The contacts come out to a connector of some
kind on the UPS, and can be used to trigger anything reasonably
low-voltage and current, like an alarm system or custom shutdown
hardware.
If you have the kind that just plays with the RS232 handshake lines,
it should be really easy to just buffer that with some transistors
or maybe a 1488 line driver chip to expand it to more computers.
If you have the kind that do a protocol, it might be tougher. Hopefully
the 'Shut down NOW!!' signal from the UPS to the PC is a one-way
signal not requiring a handshake - if so, the above method would work,
but you would do it to the data pin coming out of the UPS rather than
the handshake pin.
If you have the kind that supply a contact closure, you may have to
write your own software, but it should be easy to use the contact
closure to trigger a bit on some port on the 3 other machines that
tells the software to shutdown.
What I would do is ogle the UPS documentation and/or open up the
UPS to find out what lines are connected to its server connection.
>> Be *careful* inside the UPS! Power it down and unplug it before
fooling around in there!!! <<
If the only lines connected are the handshake lines, it's easy to
fangle a multiplexer. If you get a dry contact closure, even
easier. If the transmit data line is connected, and goes to
something resembling a microprocessor inside the UPS, your job
is harder.
Good luck and be careful! I hope this helps!
Matt Roberds
mrob...@worldnet.att.net
horse
mrob...@worldnet.att.net wrote in message
<7lhikn$4mh$1...@bgtnsc01.worldnet.att.net>...
>The UPS asserts CTS when everything is fine and drops it
>when things are not fine (power went out).
Thank you for the reply Matt,
I'll take a look at the CTS line activity,
I know that it is full RS232 cos I get reports on line condition etc
I'll plug a terminal into it, and see what gets passed
(heh - ng's makes me lazy, I should investigate first)
Unless anyone has RS232 line tap software for NT?
:-)
mrob...@worldnet.att.net
: I'll take a look at the CTS line activity,
: I know that it is full RS232 cos I get reports on line condition etc
It might be one of the other lines, but you get the idea. If you get
full RS232, it might still signal the 'power loss' condition with
dropping one of the handshake lines.
: I'll plug a terminal into it, and see what gets passed
: (heh - ng's makes me lazy, I should investigate first)
: Unless anyone has RS232 line tap software for NT?
: :-)
Not for NT, but if you have a C++ compiler for DOS and an old clunker
PC lying around with two serial ports, you can make an RS232 line
analyzer. I have done this with some software discussed in a back
issue of 'Dr. Dobb's Journal', March '97. There is a brief blurb
about it here:
http://www.ddj.com/articles/1997/9703/9703toc.htm
and the source code is here:
http://www.ddj.com/ftp/1997/1997.03/dscope.zip
I built the software and it works as advertised. I have also used
an 'official' HP serial protocol analyzer, which works too, but
DScope is much, much cheaper. :) Probably even an old 286 will
work, as I would bet the UPS is not running at a very high bps
rate (9600 tops, probably).
Good luck!
Matt Roberds
mrob...@worldnet.att.net
gre...@concentric.net
>
>mrob...@worldnet.att.net wrote in message
><7lhikn$4mh$1...@bgtnsc01.worldnet.att.net>...
>
>>The UPS asserts CTS when everything is fine and drops it
>>when things are not fine (power went out).
>
>Thank you for the reply Matt,
>
>I know that it is full RS232 cos I get reports on line condition etc
>
>(heh - ng's makes me lazy, I should investigate first)
>
>Unless anyone has RS232 line tap software for NT?
>:-)
>
a manual. In the back of the manual there is usualy
a discription of what the interface connector is doing.
Did you RTFM??
--
Just my $0.02 worth.
Hope this helps,
Gordon
Sure this is my real e-mail address. Just try
to get past my spam filters.
There are minor children in this house.
Any adult related spam will result in a
complaint to applicable athorities.
horse
gre...@concentric.net wrote in message
<7lmg9d$4...@chronicle.concentric.net>...
>You know, every APC UPS that I have seen comes with
>a manual. In the back of the manual there is usualy
>a discription of what the interface connector is doing.
>Did you RTFM??
Ah, you live in that perfect world where your
predecessors don't throw stuff away.
Apologies if my posts have pissed you off.
Adrian Godwin
horse <ho...@thrillsville.freeserve.co.uk> wrote:
>
>Ah, you live in that perfect world where your
>predecessors don't throw stuff away.
>
>
>Apologies if my posts have pissed you off.
>
Try the Linux UPS-HOWTO ; the Linux-specific parts may not help you,
but there's a lot of useful information there about cables.
-adrian
gre...@concentric.net
>
>gre...@concentric.net wrote in message
><7lmg9d$4...@chronicle.concentric.net>...
>>You know, every APC UPS that I have seen comes with
>>a manual. In the back of the manual there is usualy
>>a discription of what the interface connector is doing.
>>Did you RTFM??
>
>
>predecessors don't throw stuff away.
Oh, I see.
>
>
>Apologies if my posts have pissed you off.
Well, they didn't. It just seemed like we were all
dancing around the problem and ignoring the obvious.
Looks like I owe you the apology.
Albrecht Kadlec
> In <7ln9oa$akf$1...@news8.svr.pol.co.uk>, "horse" <ho...@thrillsville.freeserve.co.uk> writes:
> >
> >gre...@concentric.net wrote in message
> ><7lmg9d$4...@chronicle.concentric.net>...
> >>You know, every APC UPS that I have seen comes with
> >>a manual. In the back of the manual there is usualy
> >>a discription of what the interface connector is doing.
> >>Did you RTFM??
yes. I remember seeing a schematic.
> >Ah, you live in that perfect world where your
> >predecessors don't throw stuff away.
> Oh, I see.
if it's still needed, I could dig around in the manuals -
I have installed 2 APC UPS'es at a site.
mail me, if you're interested.
--
Albrecht Kadlec
Vienna University of Technology / Department of Automation
----------------------------------------------------------
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