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000279_news@watsun.cc.columbia.edu _Wed Feb 24 22:29:53 1999.msg
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From: Mickey Stein <yekkim@cts.com>
Subject: Re: Setserial High Speed Help
Date: Wed, 24 Feb 1999 19:09:30 -0800
Organization: CTS Network Services
Message-ID: <36D4BEEA.D6047B94@cts.com>
To: kermit.misc@mailrelay2.cc.columbia.edu
C Lance Moxley wrote:
> In comp.os.linux.hardware Mickey Stein <yekkim@cts.com> wrote:
> > I know I missed 99% of this thread but I've got a 16750 UART and an ISDN modem.
> > The UART is capable of 921,600 baud_total. The Modem is capable of 230400 via a
> > special command to the modem. To setup the UART via setserial in Linux, I've got
> > to use a "setserial /dev/ttySx UART 16750 baud_total 921600 baud_divisor 4
> > spd_cust" command but forgive me for the syntax errors since I'm not in linux at
> > the moment. It's close to that command anyway. This allows the UART to operate at
> > 921600 (which is the true top speed for the 16750) divided by 4 which is the
> > divisor that'll give you 230400 and then spd_cust tells it that when you set the
> > baud rate to 38,400 to REALLY run at 230,400. I know that sounds insane but do a
> > man on setserial and check it out. No way can I do a setserial 230400 or ppp baud
> > set = 230400 and get anything to work.
>
> This is the part that I need help with. My serial card has a 16650
> UART. The manufacturer says that it will go 460800bps. So you're
> saying that if I set the baud_base to 460800 and the divisor to 2
> I'll be able to get 230400bps if I use spd_cust and set my ppp to
> use 38400?
Well it sounds like you're on the right track for setserial. I'd give that a try.
> I've poured over the setserial manual but didn't figure out that
> 38400 would really mean something else.
Sorry: I thought it said that right on the man page for setserial.
> > The second part is whether you're using a modem on this serial port and if so :
> > is it an isdn modem or some modem that is really designed to operate at 230400?
> > There's only 2 isdn modems that I know of (bitsurfer and 3com iq) that'll run at
> > this speed and even then they won't take typed in "AT" commands at that speed. As
>
> I have an Eicon Diva ISDN T/A. The manual says to drive the DTE at 230400
> if you can and that's what I'm trying to do. I don't know if it will
> take AT commands at that speed or not. If not, then how do you really
> get it to run at 230400? I mean, you have to dial a number somehow.
Maybe you need to slow down and get it working at 115K first. All of these isdn modems
will talk to an async term emulator (like minicom or seyon or even the interactive mode
of kermit) at 115, but I've yet to see one that'll talk to any modem at 230K. There's a
trick (or what looks like a trick to me) and that usually consists of a special one-way
only setup string for the modem when it's in autobaud(115) mode. I think on 3com's it's
something like at $230000 or some such thing (that's definitely wrong... ) , but you
need to work out the bugs of your hookup at 115 before you commit to a mode where you
can't interactively communicate with the modem. Doesn't it say this stuff somewhere in
your modem manual? Seems like it should. In windows, there's some driver code written
that will allow switching back & forth via some tiny output i/o progs that just switch
from 230k to autobaud and vice-versa. In Linux you're on your own. It shouldn't be very
complex to figure out what was output and write your own little c program. I just never
bothered and when I want to talk to the modem and see the result of at commands, then I
reset it and it by default comes up autobaud and can be talked to without going nuts at
230k.
There's some decent info over on the Pacific Turbocomm site about this stuff (look for
their 230K switching program and linux info). Sorry but I don't have the url but just
search "Pacific Turbocomm" on altavista or something.
Anyway.. give that setserial the way you mentioned it a try and good luck with this
thing. It can be done in linux and you should be able to get both b channels working
too.
Mick
>
>
> --
> C Lance Moxley
> http://www.uiuc.edu/ph/www/clm