[comp.dcom.modems] Hardware flow control on dial in

palkovic@linac.fnal.gov (John Palkovic) (05/08/91)

I have a 2400 bd MNP5 modem connected to serial port b of a Sun 4/260
running SunOS 4.1.  Bidirectional hardware flow control (HFC) *is*
enabled in the modem (a Microcom AX/2400c) with AT\Q3.

When I dial *out*, I can enable HFC on the serial port connected to
the modem by sending STTY=crtscts and expecting "" in the chat script.
All works well with the serial port running at 9600 and using the "e"
protocol to connect to an MNP capable modem. I get 280-300 char/s
talking to a T2500 this way.

However, I would also like to have HFC when systems call me on the
same modem, so I can run the serial port and the getty at 9600. The
gettytab(5) man page does not mention anything about forcing HFC. Does
uucico(8) handle setting HFC when run as a login shell? Seems like it
should.

There are two systems that poll me at 2400 MNP4 with the "e" protocol.
I find that the file transfers *to the polling system* always fail if
the serial interface to the modem is running at 9600 bd. Backing off
to 2400 bd they are *much* more reliable, leading me to believe I have
a flow control problem. Any thoughts?

Thanks,

-John

-- 
palkovic@linac.fnal.gov || {royko,tellab5,simon}!linac!palkovic

jh@moon.nbn.com (John Harkin) (05/09/91)

palkovic@linac.fnal.gov (John Palkovic) writes:

>I have a 2400 bd MNP5 modem connected to serial port b of a Sun 4/260
>running SunOS 4.1.  Bidirectional hardware flow control (HFC) *is*
>enabled in the modem (a Microcom AX/2400c) with AT\Q3.

>There are two systems that poll me at 2400 MNP4 with the "e" protocol.
>I find that the file transfers *to the polling system* always fail if
>the serial interface to the modem is running at 9600 bd. Backing off
>to 2400 bd they are *much* more reliable, leading me to believe I have
>a flow control problem. Any thoughts?

You can enable HFC by putting ":ms=crtscts:" in the gettytab entry
for your dialin line.  For instance, I do that with a Telebit T2500
running at 19200 interface speed with this entry:

g|std.19200|19200-baud:\
	:sp#19200:ms=crtscts:to#45:de#2:

Translation:
	run at 19200
	use hardware handshaking
	timeout after 45 seconds
	delay printing a prompt for two seconds

You also need to run "ttysoftcar" in your /etc/rc so that the hardware
handshaking isn't ignored.  RTFM for more info.  :-)

John
-- 
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North Bay Network - News and mail for Marin county and vicinity