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000340_icurmtdude@yahoo.com_Thu Oct 23 12:49:07 2003.msg
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Path: newsmaster.cc.columbia.edu!panix!news.maxwell.syr.edu!postnews1.google.com!not-for-mail
From: icurmtdude@yahoo.com (icurmt)
Newsgroups: comp.protocols.kermit.misc
Subject: Re: DSR off ...
Date: 23 Oct 2003 06:51:37 -0700
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Xref: newsmaster.cc.columbia.edu comp.protocols.kermit.misc:14595
Thanks guys.
Alright, let me give you more insight to why I am seeing all these
problems. I am using the Single Board Computer to talk to the
Microcontroller unit through serial ports. The DTR pin on the SBC is
hacked to recycle the power on the MCU. Now when the communication is
initiated, the DTR pin goes high(1) which resets the MCU and
communication fails. Thats the reason that during "show comm"
I see that DSR is off. Now when the communication terminates, the DTR
is turned off (0) which turns the MCU on.
Something which puzzles me is that why is DTR handshaking used here
even when I am stating in kermit program to use the Xon/Xoff
flowcontrol. I also tried the RTS/CTS handshaking but the result was
same.
Now if I use the Java program, which uses RXTX comm jar(communication
program for Linux), then everything works fine. I see no issues. That
makes me come to the conclusion that low-level api has nothing to do
with it. It's gotta be somewhere in kermit where it is using DTR
handshaking inspite of being asked to use RTS/CTS or Xon/Xoff.
All $0.02 welcome.
Thanks - Ray
Frank da Cruz <fdc@columbia.edu> wrote in message news:<slrnbpdtri.ilh.fdc@sesame.cc.columbia.edu>...
> In article <cf6cc183.0310221148.69ac828a@posting.google.com>, icurmt wrote:
> : Thanks for your inputs.
> :
> : What looks like is that DTR pin is turned high during set line call
> : and is turned low during hangup.
> :
> That's how it's supposed to work.
>
> : If, I can keep the DTR pin low during the communication then it would
> : solve my problem. Please let me know if there's a higher level call I
> : can make through script to keep it on.
> :
> Again, device drivers handle modem signals. In general, there is no API
> for turning on and off individual modem signals, but some OS's do have this.
> However, it is rarely necessary. The functions of modem signals are clearly
> defined in the standards and if you have the appropriate cables -- i.e.
> ones that connect the right output pin on one end to the right input pin on
> the other end, everything just works.
>
> : Also read somewhere that setting speed to 0 and then turning it to
> : non-zero would flip the DTR pin as well.
> :
> It depends on the operating system. Every OS has a different API for
> "hanging up" by turning DTR off, pausing, and then turning it on. Kermit
> does this for you without requiring you to know the details if you give
> a HANGUP command on a serial-port or modem connection.
>
> - Frank