weis@netmbx.UUCP (Dietmar Weis) (03/29/91)
I have very great problems in getting a modem installation stable. It wont succeed. I can't localize the problem, I think, every component is faulty. Problems of this kind I've already encountered on many different DEC hardware: Configuration: 486 PC (DOS) with Elsa Microlink 9624 (PC-Modem-Card); and MicroVAX 3900 (Ultrix 3.1) with Racal Milgo RM32plus. Both are capable of V32 and MNP5, the RM32plus has Auto Call Back. The communication follows this scenario: 1. Microlink calls RM32plus with MNP5 + 9600 bps 2. RM32plus answers, asks for acb login and hangs up 3. Microlink hangs up as well and waits for callback 4. RM32plus calls back, Microlink answers, CONNECT 9600/REL establishes 5. PC user finally logs into the VAX Problems: 1. The VAX seems not capable of providing DTR high continuously. Every now and then DTR goes low and only sometimes goes high again (although getty is running). Doing a "file /dev/ttyxx" makes DTR go high for a while. When a call comes in in this moment, you'll get a CONNECT. In the meantime there are lots of "getty: operation would block" messages in the syslog. DEC said, set the line in /etc/ttys to shared. - OK, but every kill -HUP 1 will then change the port to "modem control off"! With DTR low the RM32plus does not answer. Forcing DTR to be high (with AT&D0 on the modem) results in a successful CONNECT, but generating a hangup on logout (with "stty hangup" configured) won't work, you can't leave the system. Here I should add: This installation is thought for the boss of the company. He won't have to do anything with AT-commands or so, he just switches power on, or says "exit" and thats it. vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv What I want is: a setup with DTR high as long as the getty is running *AND* a hangup on exit *AND* no "getty: operation would block" *AND* the port with "modem control on". ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Why can't the VAX do that ???? (Similiar things seen on: MVII/VMS, MV3100/VMS, DS200/MC) (NB: in the DS200 manual I read sth like: DTR stays only high, if CD is also high ...?) 2. Supposing, the CONNECT 9600/REL succeeds and the user logs out later on: Now it takes the Microlink more than *TEN SECONDS* to realize the loss of carrier ! A modem has to recognize loss of carrier immediately, I thought. That's a problem for the AutoCallBack mechanism: The user types his acb login and tel.no. after the initial CONNECT. The RM32plus hangs up, the Microlink not yet: the first call-back-try will now fail because of a busy Microlink phone line! Was the connect only a CONNECT 9600 or 2400 (w/o /REL) the screen is *TOTALLY* filled up with garbage during those ten seconds, even with an obviously clear phone line! vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv Why does it take so long until Microlink detects loss of carrier, and why is the screen filled up with garbage without MNP5 although the line was not noisy ?? ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ I don't have any more ideas, as I am no RS232 or modem expert. What am I missing ? Why does the same setup one time works and five minutes later doesn't ? One try out of 10 succeeds, thats not acceptable. A pure V22bis modem on another port has no problems. Do both the modems have perhaps problems with their V32 talking to each other ?? Because there are components of at least three manufacturers the support is rather weak. Pls email, any help will be very appreciated, I'm in a real mess and desperately looking for a solution. Dietmar -- weis@netmbx.UUCP | Dietmar Weis DONOP CONSULT GmbH Voice: 030/884 28 54-0 | Uhlandstrasse 179/180 Fax: 030/882 55 29 | D - 1000 Berlin 12