andrewd@cs.tamu.edu (Andrew Ted Duchowski) (04/19/91)
Hi,
A while back I posted a problem with /dev/cua locking. The problem is
now being fixed, and I thought I'd summarize the solution (note that
this may not apply to modems other than the DoveFax, also, if you
have a DoveFax and are not interested in using its data [as opposed
to fax] capabilities, ie. dialing out via /dev/cua, this may not
interest you):
The components:
-DoveFax 2400 data/9600 fax modem
-NeXT '040 cube (NS 2.0)
The symptom:
-using the modem for data (as opposed to fax),
couldn't get a hold of /dev/cua (device busy)
(there was no problem with using the modem for faxes - it worked
"out of the box", according to the manual setup)
The problem identified:
-the getty on the serial port captured the line and wouldn't let go.
It does this when it sees a DCD signal on the line. Now,
normally, some modems turn this signal on by default, but one
can force the signal off (for hayes-compatible modems, with
the AT&C1 command). The DoveFax modem has a problem in that
it puts on the CTS signal on the same pin where the computer
looks for the DCD. And so, the getty will always get the port,
hence /dev/cua busy.
Workarounds:
-basically, the modem works fine unless you need to open cua/b while there
is a getty on the line (ttyda/b).
-to dial out, one can manipulate the getty on the serial port,
depending on whether you want to dial in or out.
The solution:
-send the modem back to Dove and they'll fix the problem at
the hardware level so that the signals go to the right pins
-if you opt for the hardware solution, you'll also have to
obtain the upgraded DoveFax driver, so that the modem, when in
fax mode, will know where the right signals are (on which
pins).
Thanks for the prompt action on diagnosing and solving the problem
go to:
- Craig Goss at B&W Software who originally wrote the DoveFax driver
and who did most of the diagnosing/solving/putting_up_with_
impatient_users_such_as_myself
- Trey McStravick at Dove Tech Support for fixing the pin/signal
problem on my modem and getting my modem back to me in record time
General _personal_ impressions:
-overall, I'm impressed. My problem got fixed promptly, with minimal
hassles.
-the modem works great, I'm real impressed with the fax driver - done
in true NeXT spirit, nice interface.
-as an aside, I have to tell somebody - thank heavens for multi-
tasking. What a joy it is to dial out/fax in one window and do
other stuff in another. Anybody wanna buy an old PC?
Disclaimer:
I recall once seeing a person in Vancouver who has a DoveFax who
said that while in beta test (s)he couldn't divulge any secrets
on the modem. Why, I don't know. I also don't know what the legal
aspects are with putting people's names on comp.sys.next, or their
email addresses/phone numbers, but I did obtain permission from Craig
for putting up this solution.
I will refrain from putting up his email address and the Dove tech
support guys' phone numbers though. I imagine they're pretty busy
and may not necessarily appreciate getting extra mail/calls.
Besides that, assume the standard blurb: this isn't at all official :-)
-Andrew Duchowski
andrewd@cs.tamu.edu
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