[comp.sys.mac.comm] MNP5 Modem Problem

Michael_Carman@mindlink.bc.ca (Michael Carman) (06/05/91)

Can anyone out there in Netland help with a problem I'm having with my modem? I
have a MNP5 with v.42 and am wondering if I need a special cable to get these
features working with my Mac SE?

I'm currently using my old cable from my 1200 baud modem and, although the
modem functions fine at plain-Jane 2400 baud, I cannot seem to get it to work
as an error correcting MNP5 modem.

I recall reading somewhere that I should be using a cable that supports more
than the three pins provided by most cables but would like some confirmation of
this and suggestions as to where I might buy a proper cable. Local Apple
dealers have been no help whatsoever.

Rick_McCormack@mindlink.bc.ca (Rick McCormack) (06/05/91)

Michael Carman <Michael_Carman@mindlink.bc.ca> writes:

MC > Can anyone out there in Netland help with a problem I'm
MC > having with my modem? I have a MNP5 with v.42 and am
MC > wondering if I need a special cable to get these features
MC > working with my Mac SE?
MC > MC > I'm currently using my old cable from my 1200 baud modem
MC > and, although the modem functions fine at plain-Jane 2400
MC > baud, I cannot seem to get it to work as an error correcting
MC > MNP5 modem.
MC > MC > I recall reading somewhere that I should be using a cable
MC > that supports more than the three pins provided by most
MC > cables ...

Reading from my EMAC 2400 MNP5/v42 manual, I find there a reference to a change
in pin use depending on whether CTS is invoked (or not) with the "!C" command.
To quote: "If the !C0 command is in effect, the CTS signal is output on pin 5,
and the DCD signal is output to pin 8 (default).  If the !C1 command is in
effect, the CTS signal is not output, the DCD signal is output on pin 5, and
pin 8 is meaningless."

I traced my original problems in MNP5 connections to interactions between
RedRyder 10.4 and my settings for the EMAC, revolving around my use of the !C
command on a Mac Plus.  ( I have since found other intermittent problems -- but
they were all mine!)  Hope this helps, as I understand that the above situation
is common on many MNP5 modems using the Mac serial ports.
--
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.

dant@ryptyde.UUCP (Daniel Tracy) (06/08/91)

Responding to the following:
 
"Can anyone out there in Netland help with a problem I'm having with my modem? I
have a MNP5 with v.42 and am wondering if I need a special cable to get these
features working with my Mac SE?
 
I'm currently using my old cable from my 1200 baud modem and, although the
modem functions fine at plain-Jane 2400 baud, I cannot seem to get it to work
as an error correcting MNP5 modem."
 
I believe you need a cable that supports hardware handshaking. Just ask for
a Macintosh modem cable for V.32 modems that supports Hardware Handshaking
at your local dealer, I guess.

pda@wdl30.wdl.loral.com (Paul D Adolph) (06/18/91)

In article <33@ryptyde.UUCP> dant@ryptyde.UUCP (Daniel Tracy) writes:
>Responding to the following:
>>"Can anyone out there in Netland help with a problem I'm having with my modem? I
>>have a MNP5 with v.42 and am wondering if I need a special cable to get these
>>features working with my Mac SE?
>> 
>>I'm currently using my old cable from my 1200 baud modem and, although the
>>modem functions fine at plain-Jane 2400 baud, I cannot seem to get it to work
>>as an error correcting MNP5 modem."
>> 
>I believe you need a cable that supports hardware handshaking. Just ask for
>a Macintosh modem cable for V.32 modems that supports Hardware Handshaking
>at your local dealer, I guess.

No just about it!  I tried about 7 different sources, half of which said they
had "just the right cable" which of course wasn't, and the other half either
had no clue or were not interested in helping me.

After wasting a lot of time on the phone and in various stores, I finally
bought some connectors and cable and built my own.  With just a little
interpretation, all the info I needed I found in the manuals for my 
Classic and the modem.

However, one problem I found is that since the DTR line is used for
handshaking, you seem to lose it for other functions your terminal software
might support, ie "drop DTR on hangup" etc.  I am speaking about a Classic
here -- I don't know if this is the case for the newer machines.