From: gerg@netcom.com (Greg Andrews)
Subject: Re: SCO UNIX and Telebit Worldblazer
Organization: Netcom Online Communications Services (408-241-9760 login: guest)
Date: Fri, 2 Oct 1992 19:54:50 GMT

In article <9209261009.aa17888@dlpco.dlpco.COM> lee@dlpco.dlpco.COM (Lee Penn) writes:
>
  [ a set of register settings for his T2500 ]

Lee, your settings are very close to the ones Telebit recommends.
I''d like to insert comments on certain ones to point out the Telebit
recommendations and why they're different from yours.  This isn't a
critique - just more information to fill any gaps that might still
be remaining in people's setup information...

I'll also give the T1600/T3000/WorldBlazer equivalents.

>02/29/91  TBIT 2500 Notes for DLP Technologies, Inc.
>
>GOAL:  Lock the modem <-> server connection at 19,200 baud while
>        allowing remote users to dial in at baud rates from
>        300 -> 9600 baud using various protocols; PEP, V.42, 
>        MNP etc.
>
>TBIT 2500 register settings:
>
>        These are the ones I've changed from the factory default
>        settings:
>
>        S01=1   Answer 1 ring
>
>        S07=120 Allow enough time to connect to remote modems
>                which do not answer on the first ring.
>

T1600/T3000/WorldBlazer:  Same

Telebit recommends leaving S7 at the default of 40 for the settings
you store in your modem.  Why?  Because when your modem ANSWERS a call,
you don't want it to sit there blasting its answer tones for two minutes.
When the modem is sitting idle ready to answer a call, it's using its
stored settings.  Whenever someone calls your number, your modem will
try to connect for the number of seconds in S7.  40 seconds is enough
to get a modem connection, but not waste too much time if the call was
bogus.

Setting S7 to a high value is very useful when you dial out, but your
dialer should set that as a temporary setting, not a permanent one
stored in the modem.  That way different calls can use different S7
settings, if need be.

>
>        S45=255 Remote access enable so I can fix the modem from
>                a remote location (my home)
>
>        S50=0   Allow all baud rates to connect
>
>        S51=5   CPU <-> Modem interface speed locked at 19,200
>

T1600/T3000/WorldBlazer:  Same

Note that S51=254 would perform the same function on dial-in (selects
19200 bps), but allow you to dial out at any port speed.  S51=5 will
only allow you to use 19200 bps, period.

>
>        S52=1   DTR causes modem to hang up if it drops and 
>                modem will not answer if DTR is not active.
>

T1600/T3000/WorldBlazer:  &D2

Telebit recommends S52=2 (&D3) so the modem will reset itself when DTR
turns off at the end of each call.  This lets you set a register for
temporary use on dial-out (like the S7 stuff above), and have the modem
automatically revert back to normal dial-in settings.

>
>        S54=3   BREAK transferred out to remote system
>

T1600/T3000/WorldBlazer:  S61=0

>
>        S58=2   CTS/RTS flow control between CPU <-> Modem
>

T1600/T3000/WorldBlazer:  Same

>
>        S66=1   Lock the interface speed, use flow control
>

T1600/T3000/WorldBlazer:  S181=1 (default)

>
>        S69=1   XON/XOFF characters are passed to remote modem
>

T1600/T3000/WorldBlazer:  Same

If you've set S58=2 as you did above, this register has no effect.
The modem is not paying any attention to XON or XOFF characters,
so it's not necessary to set this register.

>
>        S92=1   Issue PEP tones last to allow for slower modems
>                to connect without agravation.  NOTE: Another
>                TBIT dialing into my system must have S50=255
>                to force a high speed connection, otherwise
>                that modem may well connect at 2400 baud.
>                When I dial out on this modem I change S50 to
>                255 to insure a high speed connection.
>

WorldBlazer:  Same
T1600/T3000:  Register does not exist (no PEP)

Also note that the other PEP modem should set their S7 register to
a large value (at least 60, often higher) so the modem will wait long
enough to hear the PEP tones and connect to them.  The computer's
software will also need to wait longer.

>
>        S95=2   MNP AutoReliable mode.  This sometimes even works
>                but I've had problems with this.
>
>        S97=1   V.42 enabled.  This is better than MNP
>
>        S106=1  V.42 will be detected, S97 must also be a 1
>

T1600/T3000/WorldBlazer:  S180=2

The newer modems use a single register to control both error control
protocols (MNP and V.42).  If you're dialing out to a modem that
doesn't have error control, you'll probably need to turn it off in
your modem also.

>
>        S111=30 UUCP G protocol selected.  I like to force this
>                since most of my connections are to uunet and 
>                sosco.  I find their modems are not always set
>                to force UUCP G.  Leaving S111 at 255 would
>                allow for automatic protocol detection.
>

T1600/T3000/WorldBlazer:  Same

Telebit recommends S111=255 for the settings you store in your modem.
The reason is the stored settings are the ones your modem will use
when it accepts incoming calls.  Just as your computer needs to be
ready to do whatever the caller wants, the modem should be ready
to handle whatever protocol the caller wants.

The rule is:  The caller should be in control, the answerer should
be passive.  The caller should set S111=30 in their modem, the answerer
should have S111=255 in their modem.  If the next caller wants to do
a Kermit transfer, they can set S111=10 and get Kermit support because
the answering modem is passive (S111=255).  If the answering modem had
S111=30, the Kermit caller would be out of luck.

When your uucp dials out, your dialer should set S111=30 temporarily.
When the call is finished, the modem will revert to the stored settings
(S111=255), ready to receive incoming calls.

>
>        S131=1  DCD is ON only when carrier is really present!
>                This is critical for proper hanging up when a 
>                remote user disconnects without logging off.
>

T1600/T3000/WorldBlazer:  &C1


Also note that Telebit recommends Q4 for the T2500/TB+/T2000/T1000 modems,
and Q2 for the T1600/T3000/WorldBlazer modems.  This makes the modem not
issue RING and CONNECT messages when it answers the phone (getty doesn't
want to get anything from the modem), but issue them when it dials
(cu and uucp DO want to get modem responses!).


-- 
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