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Path: utzoo!linus!philabs!cmcl2!seismo!brl-tgr!tgr!Morton Jim@LLL-MFE.ARPA
From: Morton Jim@LLL-MFE.ARPA
Newsgroups: net.ham-radio
Subject: PACKET TNC  RS-232
Message-ID: <10876@brl-tgr.ARPA>
Date: Tue, 21-May-85 13:53:20 EDT
Article-I.D.: brl-tgr.10876
Posted: Tue May 21 13:53:20 1985
Date-Received: Fri, 24-May-85 07:21:41 EDT
Sender: news@brl-tgr.ARPA
Lines: 19


From Morton Jim[702,703]@CCC.MFENET on May 21, 1985 at 9:39 PDT
Subject & Phone: packet

  On the serial link,  try a cable with just pins 2,3,7 .    this is the
minimum cable that will work, just transmit & recieve data and ground. you
should be able to short pin 2 to 3  on the  tnc end of the cable (without
the tnc connected)  and  what you type on keyboard should echo to the screen.
if this does not work,  you need some pins connected together on the commodore
end of the cable.  possibly 4,5,8,20  all tied together. try it again.   once
you can reliably type with this "loopback" configuration,  you can connect the
tnc and it should work.  if not,  i would venture to say something is wrong 
with the rs-232 driver in the tnc.  perhaps its levels are ok for the epson but
not for the commodore.   
   i had many problems trying to use a commercial  data cable.   i made one
with two connectors and 3 conductors of ribbon cable that has worked quite
reliably.   
good luck.
 jim morton WA6FWW