Newsgroups: comp.sys.att
Subject: Re: 3b2 EPORTS device driver bugs
From: rthomas@hakatac.almanac.bc.ca (Robert N Thomas)
Date: Tue, 05 Jan 93 04:44:08 GMT
Organization: Sir HackAlot's Castle BBS, Port Alberni, B.C., Canada

In article <1993Jan4.062531.19906@robohack.UUCP> woods@robohack.UUCP (Greg A. Woods) writes:
>However, as some of you may recall, I posted a note about a problem
>which began to plague my Hayes 2400 and Telebit T-1000 some time ago.
>
>The symptoms were a hung modem, and on the Hayes, the appearance of
>RD, SD, TR, and MR being on continuously.  

     Ah yes, the olde RD/SD light up forever problem..  Greg, try
setting setting your modems to power on default to ATE0Q1..  This
will eliminate the SD/RD light problem..  You also want the modem to
hang up and RESET when the DTR line drops...

     The next thing is in your DIALERS entries, begin these with 
ATE1Q0..  Failure to do this in your DIALERS file will cause all outgoing
UUCP and CU calls to fail..

>Since I'm too poor to afford a fancy RS-232 protocol analyser, or even
>a nice logic analyser, and my multi-channel scope is dead, I had no
>idea what was actually happening to the ports.

     The problem I saw here was a basic DATA FEEDBACK LOOP.  Any character
coming from the 3B2 hitting the modem, which in turns (ATE1) echos this 
character back to the 3B2.. The 3B2 echos the character back to the MODEM
(3B2 is a FULL DUPLEX machine), and then the modem Re-ECHOing the character
back to the 3B2 (ATE1 setting) and round and round it goes...

      Hence the modems SD/RD lights stay ON..

>The only solution to this lockup is to either cycle the power on the
>affected modem, or to re-pump the firmware to the EPORTS card.

     Yup, re-pump of firmware would temporarily cause the EPORTS card not
to echo data, hence FEEDBACK loop stops..  Cycling power on the modem, causes
simular effect...

>Eventually I discovered that running the modems with DCD in what I
>call "interrupt" mode (i.e.  S131=3 on the T1000, or AT&C3 on other
>conventional modems) effectively solved the problem.  (The Hayes
>SmartModem 2400 couldn't do this, but since I only use it to dial out,
>I can use AT&C0 for it.)

     Yup..  You got it, this is what I refer to a 3B2 friendly MODEM..  I do
the exact same thing here as well (ATS131=3 for my TB2000 modem).  For my
US Robotics HST modem, it cannot PULSE the Carrier Detect line, rather,
it PULSES the Data Set Ready (DSR) line { AT&S1S24=250 } so I made a special
connector for the HST which connects the HST's DSR line to the 3B2's carrier
detect line (CD)..  Works great, same result...

     In otherwords greg, see if there is some other signal that you can PULSE
on hangup, and use it for the 3B2's Carrier detect instead!

>My original single-entry dialer had not used '\m', but since this is
>the secret to having cu(1) say "disconnected" when the modem drops
>DCD, I put it back in the dialer sequence.

    My system does not use \m, because when the modems PULSE the CD line,
the 3B2 say's DISCONNECTED..

>Since that time, every (successful?) call out results in a subsequent
>(but random?) series of locked up modems.  Eventually the frequency of
>lock-ups is reduced.  (So I've again removed the clocaloff invocation,
>and have gone back to ensuring I use '~.' to end calls).

    The modem PULSING the 3B2's CD line results in a nice proper
disconnect..  If the remote system drops me, or if the 3B2 drops the line,
makes no diference here...

>     Does anyone have access to source for the EPORTS drivers
>and firmware, and perhaps the ability to get this fixed and release
>the fix?  While you're at it, could the hardware flow control be fixed
>such that it can be permanently enabled at boot time for a given port?

     I know whatche mean about the hardware flow control hastle..  While
your at it Santa, could to fix the drivers so the XON/XOFF and HFC can
both be enabled at the same time???   Would be nice, and thanks..  Well,
I don't know if that helps you all the much Greg, you have an idea of
what I do here to get by..


Cheers...

					---- Robb ----
Xref: sparky comp.sys.att:2811 comp.sys.3b1:4168