[comp.sys.sgi] serial line again

jit@slic.cellbio.duke.edu (Jit Keong Tan) (04/24/91)

Help.

Does anyone know what are the differences/limitations between
the different /dev/tty???'s ?
Specifically, where is the documentation that explains
each one of them.  Hopefully there is only one document that
briefly covers the functions of each tty??.

Thanks.

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Dan Karron@UCBVAX.BERKELEY.EDU (04/24/91)

I have wasted lots of time trying to
break into the serial world > 9600 baud.

Lots of things don't work as advertized
at exotic speeds. Patience, a breakout box
and lots of testing is required.

| karron@nyu.edu (e-mail alias )         Dan Karron, Research Associate      |
| Phone: 212 263 5210 Fax: 212 263 7190  New York University Medical Center  |
| 560 First Avenue                       Digital Pager <1> (212) 397 9330    |
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blbates@aero36.larc.nasa.gov (Brent Bates ViGYAN AAD/TAB) (04/24/91)

   I am using a Kurta digitizing tablet on our 4D/340 VGX at 19200 Baud
with no problems (now!).  Baud rate was never one of my problems, but
I had plenty of others to take its place.

	Brent L. Bates
	NASA-Langley Research Center
	M.S. 361
	Hampton, Virginia  23665-5225
	Phone:(804) 864-2854          FAX:(804) 864-6792
	E-mail: blbates@aero36.larc.nasa.gov or blbates@aero8.larc.nasa.gov

vjs@rhyolite.wpd.sgi.com (Vernon Schryver) (04/24/91)

In article <9104231740.AA22383@slic.cellbio.duke.edu>, jit@slic.cellbio.duke.edu (Jit Keong Tan) writes:
> 
> Does anyone know what are the differences/limitations between
> the different /dev/tty???'s ?
> Specifically, where is the documentation that explains
> each one of them.  Hopefully there is only one document that
> briefly covers the functions of each tty??.


ttyd* is a standard 3 wire DTE:			RD,TD,SG
ttym* is a normal 5 wire, "modem control" port: RD,TD,SG,DCD,DTR
ttyf* is a "hardware flow control" port:	RD,TD,SG,DCD,DTR,RTS,CTS

Read Chapter 10 of "IRIX System Administrator's Guide", document
number 007-0606-030.



Vernon Schryver,  vjs@sgi.com

rpaul@crow.UUCP (Rodian Paul) (04/24/91)

> I have wasted lots of time trying to
> break into the serial world > 9600 baud.
> 
> Lots of things don't work as advertized
> at exotic speeds. Patience, a breakout box
> and lots of testing is required.
> 

Oh, I don't quite agree. I hooked up a couple of Telebit T-2500's at 
19200 without any problems. You do need to use the hardware-hanshaking
devs (/ttyf?). 

-------------------------------------------------------------------------------
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Dan Karron@UCBVAX.BERKELEY.EDU (04/24/91)

Sorry, I did not mean that sgi serial did not
work well. I meant that lots of peripherals don't work
well at the upper limits of their speeds.

I did have some problems on a 70G box with serial
io, but that was cured by upgrading to a 85GT.

I find that at high speeds xon/xoff from a peripheral
may not be fast enought, and lots of peripherals don't stop
blabing on time. Lots of of patching of pins 4,5,8 and (9)20 
is usually required for hardware handshake.

Anyway, once I solved the problems, they have stayed solved,
and all is wonderful. Sgi serial buffers work just fine
at high speed.

>Subject: Re:  serial line again
>In-Reply-To: your article <9104232000.AA17240@karron.med.nyu.edu>
>News-Path: sgi!decwrl!ucbvax!UCBVAX.BERKELEY.EDU!"Dan Karron
>
>> I have wasted lots of time trying to
>> break into the serial world > 9600 baud.
>> 
>> Lots of things don't work as advertized
>> at exotic speeds. Patience, a breakout box
>> and lots of testing is required.
>
>What exactly did not work, that SGI advertized to work, at speeds > 9600?
>
>/be
>
| karron@nyu.edu (e-mail alias )         Dan Karron, Research Associate      |
| Phone: 212 263 5210 Fax: 212 263 7190  New York University Medical Center  |
| 560 First Avenue                       Digital Pager <1> (212) 397 9330    |
| New York, New York 10016               <2> 10896   <3> <your-number-here>  |

uh311ae@sunmanager.lrz-muenchen.de (Henrik Klagges) (04/25/91)

Hello !
I just wonder why there is a need for hardware handshakers (ttyf's).
I have no problem running the standard 4DGifts kermit at 19200. I 
couldn`t try 38k because I don't have a 2nd 38k thing.
 BTW, if I want to make SGI-SGI serial line transfer, would I have to
switch wires in the serial line ? Recently, I had some nice "Panic:
IRIX killed due to memory error at physical address ..." on one machine.
I installed an inst kernel in the swap space, but couldn't use internet
without restarting (ie, blowing) the machine. I could mount /dev/dsk* 
unto the 2nd kernel - but transfering a 780 MB disc via kermit isn't
the usual choice, especially not via a PC.

Cheers ! Rick@vee.lrz-muenchen.de

vjs@rhyolite.wpd.sgi.com (Vernon Schryver) (04/26/91)

In article <uh311ae.672564381@sunmanager>, uh311ae@sunmanager.lrz-muenchen.de (Henrik Klagges) writes:
> Hello !
> I just wonder why there is a need for hardware handshakers (ttyf's).
> I have no problem running the standard 4DGifts kermit at 19200.


Many protocols work well enough without hardware handshaking because
they do their own windowing (which reduces the likelihood of overruns)
and error recovery (which fixes the overruns that do happen).  Still
hardware flowcontrol is A Good Thing.


Vernon Schryver,   vjs@sgi.com

dwatts@ki.UUCP (Dan Watts) (04/27/91)

In article <9104240327.AA29314@crow.omni.co> rpaul@crow.UUCP (Rodian Paul) writes:
>> I have wasted lots of time trying to
>> break into the serial world > 9600 baud.
>Oh, I don't quite agree. I hooked up a couple of Telebit T-2500's at 
>19200 without any problems. You do need to use the hardware-hanshaking
>devs (/ttyf?). 

I've got one Telebit T-2500 and one Trailblazer Plus hooked into
our Personal Iris with the baud rate set to 19200 and I use the
/dev/ttym? ports.  When I first tried getting things to work with
/dev/ttyf? ports, I ran into problems (Irix 3.2).  I use both modems
as dial in/out. I'm now at 3.3.1 (3.3.2 tapes are on my desk) so maybe
things have changed.
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