Bitsurfr and ISDN
Josip Loncaric
(Terry L. Hipsher) wrote:
> I had problems disconnecting using Mac PPP 2.20a, then I changed my init
> string from &d2 to &d0 and I don't disconnect anymore.
That observation is correct. A Macintosh serial port has only ONE
handshaking output, which a proper high speed handshaking cable wires to
BOTH pins 4 (RTS handshaking) and 20 (DTR hangup) on the modem (or
BitSURFR). This means that if MacPPP is configured to use hardware
handshaking, specifying &d2 in the initialization string WILL DROP
CONNECTION as soon as the RTS is de-asserted for more than the time
specified in register s25 (DTR delay time).
My understanding is that PPP must use hardware handshaking with high speed
modems (or ISDN TAs). Therefore, Mac users are left with two choices:
(1) Set up the modem (or BitSURFR) to ignore DTR, or,
(2) Set up the s25 register as high as possible (s25=255 gives delay of
2.55 seconds) and hope for the best.
At this moment, I am using the second solution. My BitSURFR is
initialized by MacPPP as follows:
at &f0 %a2=95 &d2 s25=255
where
&f0 loads factory profile #0, which ignores DTR
%a2=95 specifies PPP protocol
&D2 sets BitSURFR to hangup on DTR drop
S25=255 sets DTR drop response time to 2.55 seconds
I am connecting to PSI's InterRamp service, using a Power Macintosh,
MacPPP 2.2.0a, and BitSURFR (firmare rev. 1D). The above setup allows
hardware flow control without unwanted disconnects as long as the Mac does
not block input for 2.55 seconds or more, but without any guarantees. The
Mac could decide to drop RTS and DTR longer, and then you'd have a
disconnect, but in my case this has not yet happened (I did have several
disconnects before increasing the s25 setting to 2.55 seconds).
The alternative initialization would be simply "AT&F0%A2=95" but this
requires the Mac to hang up in software. If the software fails to do this
for whatever reason (eg. it crashed), then you stay on line -- at $x/hr,
until you correct the situation in person. This is kind of risky -- so
I'll use the DTR recognition delay as long as it seems to work.
BTW, the PSI/Motorola recommended initialization "at&f&c1&d2%a2=95\q3&m1"
is perhaps good for IBM PC compatibles, but certainly not for
Macintoshes. Here is why:
(i) On a Mac, modem's CD line is wired to GPi, which Mac serial port
driver ignores. Therefore, &c1 is irrelevant.
(ii) Since Mac wires RTS and DTR together, hardware handshaking which
exceeds delay specified in s25 WILL DROP CONNECTION. The default time in
s25 is only 0.05 seconds, which means that &d2 specified above will cause
disconnect as soon as the Mac's input buffer fills up for 0.05 seconds or
more.
(iii) Factory setting &f already includes RTS/CTS handshaking, so \q3 is
redundant.
(iv) The &m1 (DTE synchronous mode 1) probably should not be there,
although Motorola claims that some configurations need it for reasons
which escape me (and them, it seems). The DTE interface to the Mac is
asynchronous, and %a2=95 causes the BitSURFR to do PPP-style async-to-sync
conversion. My setup worked either way (default asynchronous DTE (&m0) or
synchronous &m1) presumably because %a2=95 overrides this setting, so I
decided to leave the &m parameter alone and stick with the &f0 default.
I hope this helps.
--
Josip Loncaric <jo...@interramp.com>
Corey M. Horowitz
<josip-02099...@ip194.baltimore.md.interramp.com>,
jo...@interramp.com (Josip Loncaric) wrote:
> I hope this helps.
>
> --
> Josip Loncaric <jo...@interramp.com>
Maybe you can help me. I'm trying to get my bitsurfr to work
with my
powerbook 180 with a NYNEX ISDN connection. The second voice
line is
working fine but when I try to connect to interramp with
ConfigPPP I
get a "PPP timeout". We've tried different init strings but
the best I
could do was get an error message stating that either the
modem was turned
off or my cable didn't support CT S flow control.
I'm using the same cable I use in the office for a 28.8
interramp
connection with a Supra modem. I am configured for hardware
handshaking
and the CTS/RTS selection is highlighted.
Is there some special cable I need for the bitsurfr? Is my
bitsurfr
configured properly? ( I entered the spid #'s and set
protocol to sync2.
The led's are green and the voice line works.
Thanks
Josip Loncaric
C...@interramp.com (Corey M.
Horowitz) wrote:
> Maybe you can help me. [...]
First, make sure you have a "hardware handshaking cable" for
your
PowerBook, then, make sure your ConfigPPP is set up to use
hardware
handshaking ("CTS & RTS (DTR)" setting), and try the
initialization
strings that work for me (either "at&f0%a2=95" or
"at&f0%a2=95&d2s25=255").
One final point: I have been instructed to change ConfigPPP
configuration
as follows:
(1) Click on "Config..." button
(2) Click on "LCP Options..." button
(3) UNcheck "will" under Remote/Max. Receive Unit
If the above fails to work for you, I do not have further
ideas.
--
Josip Loncaric <jo...@interramp.com>