From: swhite@tybse1.uucp (William C. "Spike" White)
Subject: HELP requested for UUCP & Hayes ULTRA modem
Organization: Tybrin Corporation, Shalimar, FL
Date: Mon, 13 Apr 1992 20:25:55 GMT
Keywords: UUCP, Hayes Smartmodem

   We are using a Hayes ULTRA Smartmodem 9600 with an AT&T 3B2 running SVR3
Unix (BNU UUCP).  This, apparently, is a marriage made in hell.  We have
experienced numerous major problems which we've had to solve ourselves.  The
AT&T technical support personnel didn't seem interested in supporting anything
other than their modems and the Hayes support personnel seemed quite helpful,
but only seemed to know DOS. 

   We are down to the last 5-10%, the "highly technical" stuff. We still have 
some difficulties, principally in the area of flow control.  

   The 3B2 serial ports, by default, do XON/XOFF (i.e. software) flow control.  
Only by disabling all SFC and then running a special command, epstty, can HFC be
enabled.  The serial port settings other than the baud rate *SEEM* hard-coded 
into uucico.  I've looked up these setting and it appears they enable XON/XOFF 
flow control.

   Here's the info Hayes provides in its modem's manual:

   CCITT recommendation V.42 specifies RTS/CTS and XON/XOFF as flow control
   methods for error-control connections. V-series system products also offer
   transparent XON/XOFF for situations where the hardware does not support
   RTS/CTS flow control, and the type of data being transferred prevents the
   use of standard XON/XOFF.  Transparent XON/XOFF permits the transfer of
   XON/XOFF characters by "hiding" them during transmission and "revealing"
   them after reception.  This capability must be supported by your
   communications software.

   Since this modem is used to transfer our LD USENET feeds nightly, it's
important that it run as fast and efficiently as possible.  I've examined the 
connections to the modem on the other end, and the connection is made at 
9600 baud with full data compression (V.42bis), error control (LAP-M), etc. 
The two uucico daemons always agree to use uucp's g protocol. I'd like to 
connect from the computer to the modem at 19200 or 38400, which is the fastest 
speed that the 3B2 supports.  The modem and the computer are inches from each 
other, so serial line length is not a problem.  The modem is on a serial port 
bank all by itself (i.e., an EPORTS card), so 19200 or 38400 baud to the 3B2 
shouldn't be a problem.

   Yet when I connect up at 38400 using XON/XOFF flow control, there are
problems. If I run in error control mode, the debug logging reports numerous
alarms and the file transmission falls part-way through.  If I connect as
above, but in "asynchronous mode with automatic speed buffering", the file
transmission succeeds, but *EXTREMELY* slow.  It catches alarms every now and
then, but seems to recover from them.

   My question is: how should I configure this modem and the computer?  The
modem connects and "talks" to the computer at 38400.  Is there any problem
with running a Hayes V-series ULTRA at this speed? What flow control should I
use?  Does uucp's g protocol faithfully transmit binary files (such as 
compressed news feeds) when using XON/XOFF flow control?  Or does it support
"transparent" XON/XOFF flow control (whatever that is)?  Or (best of all) can I
configure uucico somehow to use RTS/CTS hardware flow control?

   Please send e-mail directly to me and, if there's enough interest, I'm
summarize and post a follow-up article.

Spike White
Tybrin Corporation
e-mail: swhite@afseo.eglin.af.mil uunet!sci34hub!tybrin4!tybse1!swhite
-- 
Spike White
e-mail: swhite@afseo.eglin.af.mil uunet!sci34hub!tybrin4!tybse1!swhite
Newsgroups: comp.mail.uucp