Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!gatech!ncar!tank!uxc.cso.uiuc.edu!uxc.cso.uiuc.edu!ux1.cso.uiuc.edu!uxe.cso.uiuc.edu!mcdonald
From: mcdonald@uxe.cso.uiuc.edu
Newsgroups: comp.sys.ibm.pc
Subject: Re: RS-232 protocol primer (long)
Message-ID: <45900244@uxe.cso.uiuc.edu>
Date: 26 Jun 89 13:32:00 GMT
References: <589@megatek.UUCP>
Lines: 37
Nf-ID: #R:megatek.UUCP:589:uxe.cso.uiuc.edu:45900244:000:1210
Nf-From: uxe.cso.uiuc.edu!mcdonald    Jun 26 08:32:00 1989


> |> Why is the word STANDARD in quotes?  There is, in fact, a REAL LIVE
> |> EIA standard, designated RS-232-C and dated 1981.  (Originally 1969,
> |> reaffirmed 1981.)  It DOES NOT specify the DB-25 interface connector,
> |> or any interface connector at all.  It DOES specify:

>The sex of the connector.

>3.1  The interface between the data terminal equipment and the data 
>communications equipment is located at a pluggable connector signal interface
>point between the two equipments.  The female connector shall be associated
>with, but not necessarily physically attached to the data communications 
>equipment..."

What's a DCE or a DTE? I never use those words. To be a useful standard,
it should specify the sex of the connector for each particular type
of equipment, by its common name:
1. Computers  -  odd, it never seems to mention computers!!!!

2. Terminals  - Presumably computers and terminals should be the same
    sex.

3. Printers

4. Modems

5. Scanners

6. Data collection equipment (voltmeters, etc.) - presumably the same as 
   scanners

7. whatever else people can think of

And, of course, the question of the function of pins 2 and 3 has to be
worked out!!!

Doug McDonald