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000243_fdc@columbia.edu_Fri Dec 14 19:34:10 EST 2001.msg
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Article: 13068 of comp.protocols.kermit.misc
Path: newsmaster.cc.columbia.edu!news.columbia.edu!news-not-for-mail
From: fdc@columbia.edu (Frank da Cruz)
Newsgroups: comp.os.linux.misc,comp.protocols.kermit.misc
Subject: Re: Help with UPS / Serial Ports
Date: 14 Dec 2001 19:33:24 -0500
Organization: Columbia University
Lines: 31
Message-ID: <9ve5ok$gif$1@watsol.cc.columbia.edu>
References: <3c15cc89$0$227@hades.is.co.za> <3c197fe9$0$233@hades.is.co.za> <9vd2iu$l74$1@watsol.cc.columbia.edu> <9ve1qn3qqm@enews2.newsguy.com>
NNTP-Posting-Host: watsol.cc.columbia.edu
X-Trace: newsmaster.cc.columbia.edu 1008376406 12078 128.59.39.139 (15 Dec 2001 00:33:26 GMT)
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NNTP-Posting-Date: 15 Dec 2001 00:33:26 GMT
Xref: newsmaster.cc.columbia.edu comp.os.linux.misc:530739 comp.protocols.kermit.misc:13068
In article <9ve1qn3qqm@enews2.newsguy.com>,
those who know me have no need of my name <not-a-real-address@usa.net> wrote:
: <9vd2iu$l74$1@watsol.cc.columbia.edu> divulged:
: >In article <3c197fe9$0$233@hades.is.co.za>,
: >Peet Grobler <peetgr@absa.co.za> wrote:
:
: >: I have three boxes (four soon) powered by this UPS, and only one can
: >: connect directly to the UPS. I've got to write a server, and some
: >: clients for the other three machines, so they all know when to shut
: >: down. Besides, it's more fun rollin' my own!
:
: >C-Kermit 8.0, which is being released now, supports RFC 2217 Com Port
: >Control, which lets you share serial ports over Telnet.
:
: but only one at a time, right? all `n' systems being supported by the ups
: need notification. were you thinking periodic `connect, poll, disconnect'
: operations by each client? that could get messy.
:
Only one process can have a serial port at a time (oversimplified but
you get the idea). So either processes have to take turns, or you have
to write a server that owns the serial port and acts as a mediator for
other processes, perhaps on other hosts, to make queries and get results
or whatever. This approach would probably be most appropriate to this
application, but it's going to be a fair amount of work, so taking turns
with existing tools might be an easier way to get started. It's simple
to script in Kermit: try to open the device; if you fail, sleep for bit
and try again. Once you have it, make your query, get the results,
close it, and sleep for some (perhaps randomized) period of time to give
the others a chance.
- Frank