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From: smith@umn-cs.UUCP
Newsgroups: net.dcom
Subject: Re: Wanted: info on EIA RS-232 - (nf)
Message-ID: <348@umn-cs.UUCP>
Date: Sat, 22-Oct-83 21:01:05 EDT
Article-I.D.: umn-cs.348
Posted: Sat Oct 22 21:01:05 1983
Date-Received: Tue, 25-Oct-83 01:41:19 EDT
Sender: notes@umn-cs.UUCP
Organization: Computer Science Dept., U of Minn, Mpls, MN
Lines: 30

#R:hogpc:-27000:umn-cs:1600002:000:1026
umn-cs!smith    Oct 21 13:01:00 1983

The 'absolute minimum RS-232C' I've ever seen is three wires: transmit,
receive, and signal ground.  Will this work for you?  No way to tell without
knowing what you're hooking together.  Here are observations based on
my own experiences:

1. Everyone expects at least transmit, receive, and signal ground.

2. I've seen few systems that really require a RING signal.

3. Many (but not all) connections use Data Terminal Ready (DTR) or
   Data Set Ready (DSR) to tell if there's something connected.  Dropping
   one of these (depending on your direction) "disables" the connection.

4. Carrier Detect is usually important if you're connecting to a modem.

5. Some people use Request to Send/Clear to Send (RTS/CTS) instead of or
   in addition to DTR/DSR.

6. Any of these signals can usually be strapped permanently 'on' when
   you build the interconnecting cables.  This takes away your control
   but can make otherwise impossible things work.

Rick Smith.
U. Minnesota
[smith.umn-cs@Rand-Relay]
 [...ihnp4!umn-cs!smith]