jnelson@trwrba.UUCP (John T. Nelson) (12/11/84)
Subject: Driving modems with tip.... Newsgroups: net.unix-wizards,net.dcom This is too bizzare to believed! Apparently my problems have nothing to do with the type of modem that I am using. Rather I am getting some kind of strange intermittent behavior from either the tip software or perhaps the DEC hardware. I suspect that tip has problems, but let's see what you think... The modems connected to my VAX are of the autodial/autoanswer variety. As autoanswer modems they are flawless and perform like champs. When I try to drive them with tip, however, sometimes the modem works.... 90 percent of the time I get nothing on my screen. Sometimes the modem echos every other character (which I do not attribute to the modem since it works fine when connected ONLY to a terminal). Sometimes I receive pseudo-garbage. I've checked every piece of hardware in the loop and reloaded tip from the distribution tapes... yet still no dice. I've used different makes of modems and different cables and used different ports on my DMF32 to boot (you get 2 full modem control ports on a DMF32). If the DMF32 were the culprit, wouldn't the autoanswer modems also produce garbage? Everything goes to hell when I use tip... that's the common factor! Help... whimper - John
jerry@oliveb.UUCP (Jerry Aguirre) (01/19/85)
The every other character symptom sounds like two processes trying
to read the same line. Is the line enabled for login at the time you
are trying to autodial?
As I understand using the same line for auto-answer and dialout can only
be done if you modify the tty driver to arbitrate between the two.
Jerry Aguirre @ Olivetti ATC
{hplabs|fortune|idi|ihnp4|tolerant|allegra|tymix}!oliveb!jerrylarry@anasazi.UUCP (Larry Rodis) (01/23/85)
> The every other character symptom sounds like two processes trying > to read the same line. Is the line enabled for login at the time you > are trying to autodial? > > As I understand using the same line for auto-answer and dialout can only > be done if you modify the tty driver to arbitrate between the two. > > Jerry Aguirre @ Olivetti ATC > {hplabs|fortune|idi|ihnp4|tolerant|allegra|tymix}!oliveb!jerry You do not have to modify tty driver to allow dial out and dial in on the same line at least note on System and several pc versions of unix. All that needs to be done is for the program that uses the line to dial out must check to see if the line is in use and if not disable the getty from running on the line.(On sys V this is done by changing to an init level which that oarticular line does not support.) Once this is done the program is free to use the line for dialout purposes. When the program is ready to terminate all that needs to be done is to re-enable the line and start the getty(sometimes this is done automatically). Larry Rodis @ Anasazi uucp: ..decvax!noao!terak!anasazi!larry ..ucbvax!asuvax!anasazi!larry -Currently asuvax is down.
wls@astrovax.UUCP (William L. Sebok) (01/28/85)
>> As I understand using the same line for auto-answer and dialout can only >> be done if you modify the tty driver to arbitrate between the two. >> Jerry Aguirre @ Olivetti ATC > >You do not have to modify tty driver to allow dial out and dial in on the >same line at least note on System and several pc versions of unix. All that >needs to be done is for the program that uses the line to dial out must check >to see if the line is in use and if not disable the getty from running on >the line.(On sys V this is done by changing to an init level which that >oarticular line does not support.) Once this is done the program is free to use >the line for dialout purposes. When the program is ready to terminate all that >needs to be done is to re-enable the line and start the getty(sometimes this is >done automatically). > Larry Rodis @ Anasazi It is also not necessary to modify the tty driver in 4.1 or 4.2 BSD to use the same line for auto-answer and dialout (although modifying the driver is another way to do it). See my recent posting to net.sources to see how it is done. The hardest thing is to do is enabling/disabling modem control on that line. One wants modem control enabled on dialin so that the computer can sense when the caller hangs up. However unless modem control is disabled on dialout the computer cannot (with present unix tty driver behavior) communicate with the modem to cause it to dial the desired number. -- Bill Sebok Princeton University, Astrophysics {allegra,akgua,burl,cbosgd,decvax,ihnp4,noao,princeton,vax135}!astrovax!wls