[net.periphs] Flow Control Trouble with `lpd'

jbs@mit-eddie.MIT.EDU (Jeff Siegal) (10/31/86)

I'm trying to connect a laser-printer to a 9600 baud line on a Ultrix
1.1 (call it 4.2 BSD) uVAX.  When I write directly to (say) /dev/tty02
(e.g. with `cat'), all is well, but when I attempt to use lpd to
manage the printer, Unix does not seem to honor the XOFF (and XON)
characters sent by the printer when its buffer fills up.  Data gets
lost.  How can I fix this?  I don't have the source code.  I don't
want to drop the baud rate, because this will greatly increase the
time to print graphics, down-load fonts, etc (and besides, it is only 
a partial solution, not handling cases like paper-out, etc.)

Jeff Siegal

roy@phri.UUCP (Roy Smith) (11/01/86)

In article <3650@mit-eddie.MIT.EDU> jbs@mit-eddie.UUCP (Jeff Siegal) writes:
> When I write directly to (say) /dev/tty02 (e.g. with `cat'), all is well,
> but when I attempt to use lpd to manage the printer, Unix does not seem
> to honor the XOFF (and XON) characters sent by the printer [...]

	We had just this problem last week -- turns out that we didn't set
the tty flag bits right in /etc/printcap.  Make sure you're not running in
RAW mode; if you don't explicitly clear the RAW (040) bit in the tty flags,
it may end up set by accident.  You might also want to turn on the LDECCTQ
bit so only ^Q restarts output, just in case your printer like to send back
random trash between a ^S and the matching ^Q.  Try something like:

	br#9600:rw:fc#0000374:fs#0000003:xc#0:xs#0040040
-- 
Roy Smith, {allegra,philabs}!phri!roy
System Administrator, Public Health Research Institute
455 First Avenue, New York, NY 10016