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000120_fdc@columbia.edu_Fri May 30 16:28:23 EDT 2003.msg
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Article: 14345 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.protocols.kermit.misc
Subject: Re: Mac OS X, Break, and Keyspan USB Twin Serial Adaptor
Date: 30 May 2003 16:28:02 -0400
Organization: Columbia University
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Message-ID: <bb8esi$6o3$1@watsol.cc.columbia.edu>
References: <ac67ee9b.0305281820.6fd13658@posting.google.com> <bb5114$5co$1@watsol.cc.columbia.edu> <bb89d0$m7v$0@206.231.158.3>
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Xref: newsmaster.cc.columbia.edu comp.protocols.kermit.misc:14345
In article <bb89d0$m7v$0@206.231.158.3>,
Josh Kuperman <josh@imac.ssimr.com> wrote:
:
: OK I tried the modem, using and old USB Sportser 28.8. The thing has
: the following lights: AA, CD, RD, SD, TR, CS, and ARQ/FAX. It made
: no difference if I was in command more or connect mode. I did issue
: an ATZ command and I don't have any phone lines connected. All I had
: to measure time is an old horse trainers stop watch; accurate but
: 1/5 second increments. The TR and CS lights are always on. When I
: issued the Break Command both the SD and RD came on -- for 1 second
: with "output \b" and two with "output \l". Since you said the TxD
: (which I'm taking to be the same as SD on this modem) should come on
: but nothing else I'm assuming that either Keyspan or Kermit or the
: MacOS is generating and inappropriate signal.
:
Actually I think this indicates Kermit is working sort of right. The
timing might be off, but that shouldn't matter (formally, a Break is a
spacing condition lasting *at least* 250 msec). As for RD coming on at
the same time, it could be that your modem is just echoing it back.
: I have also found that I might have some timing issue where I
: connect and don't seem to be able to communicate with the device at
: all, but just get messages like "Can't send character: Undefined
: error: 0 " I can exit out of kermit and get back in but I do seem
: to ofter wind up in an envrionment where key strokes are either
: being delayed or ignored.
:
OK, that's worrisome. A debug log might show you where this is
happening. This is CONNECT mode, right? "Error 0" usually means
the application told the OS to write() n characters, and write()
returned indicating no (zero) characters were written, yet did not
set an error code.
Not having hands-on access to Mac OS X, and not knowing anything about
its serial interface, I can't say for sure why this would happen, but
one guess is that it's not getting certain modem signals that it likes
to have such as DSR (but not CTS if your modem's CS light indicates CTS).
: In repsonse to two other issue: I've never seen a Mac Null Modem
: cable, everyone uses printer cables -- but that doesn't mean it is
: the same as a printer cable.I don't think it matters.
:
Famous last words :-)
: And I was
: using the correct control characters but often not getting the
: correct responses.
:
If it works sometimes but not others, suspect a loose connection.
I know this sounds obvious, but (here comes a story...)
Once many years ago my boss's boss's boss's boss got a Macintosh and
wanted to be able to connect its serial port to our data switch to get
at e-mail. We set it up, put Kermit on it, plugged it in, everything
was fine except it would not communicate. We checked everything, found
nothing wrong, and left very embarrassed. Eventually it turned out
that the rubber sleeve on the Din-8 connector was just a tad too long;
even though it was plugged firmly into the Mac, contact was not made.
Hopefully DB-9 connectors are better standardized than Din-8's, but
still I would not necessarily trust a printer cable to do null-modem
duty. Anyway, I don't even know what a Mac OS X box uses for a
serial port -- is it RS-232, RS-423, or what? That is, does it even
have modem signals?
- Frank