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From: lriggins@blackbird.afit.af.mil (L. Maurice Riggins)
Newsgroups: comp.sys.mac.comm
Subject: Re: Using hardware handshaking
Message-ID: <1770@blackbird.afit.af.mil>
Date: 27 Nov 90 22:33:51 GMT
References: <1990Nov26.183217.236@skbat.csc.ti.com>
Distribution: usa
Organization: Air Force Institute of Technology; WPAFB, OH
Lines: 48

Here's how your cable should pin out for each
of the types of handshaking:

Mac		Xon/Xoff	Hardware
Mini-		Handshake	Handshake
Din 8		DB-25		DB-25

1 (HSK0)	20 (DTR)	4 (RTS)
2 (HSK1/Xclk)	 6 (DSR)	5 (CTS)
3 (Tx-)		 2 (TxData)	2 (TxData)
4 (Gnd)		 7 (SigGnd)	7 (SigGnd)
5 (Rx-)		 3 (RxData)	3 (RxData)
6 (Tx+) No Connection
7       No Connection
8 (Rx+) No Connection

Since the modem will no longer see DTR from the Mac,
you will have to set the modem to ignore DTR.  And 
since there is no connection for the DCD, you may as
well set it high on the modem. AT&C0&D0&W0 will do this.

You also have to tell your telecomm software to use
Hardware Handshaking instead of Xon/Xoff.

If your modem supports v.42, you can set the baud rate
in the telecomm program for 4 times the modems top rate.
If you only have MNP5, you can set the telecomm baud
rate for 2 times the modems top rate.  This speed between
the computer and modem is called DTE speed and is usually
reported by the CONNECT string.  However, this speed 
given that you are using hardware handshaking, has little
to do with the speed between the two modems (which is called
DCE speed and is reported by the CARRIER string (if enabled).

When you dial out, the modem will negotiate the highest
speed and level of error correction with the answering
modem.  It will probably be lower than your speed between
Mac and modem... that's okay, that's what the handshake is
for.

Hope this helps a bit,


-- 
Maurice      INTERNET:    lriggins@blackbird.afit.af.mil (129.92.1.2)

      Opinions expressed here do not reflect those of my employer nor
      constitute an official position of any U.S.Government agency.