Date   : Wed, 15 May 1996 00:10:10
From   : Keith ELMO Eldridge <elmo@...>
Subject: Re: BBC <-> PC connexion, the final message

>Just to annoy you again, one stupid question:
>what are the positions of the pins of the RS232.

Depends on the type of connector and somtimes the type of machine.


Having disected the cable that I use this is what I found :-

9 Pin   25 Pin    PC                       BBC            5 Pin DIN
D-Type  D-Type    ==                       ===             Domino
  5       7       0V            <--------> Gnd               C
  2       3       Data In (RxD) <--------> Data Out (TD)     B
  3       2       Data Out (TxD)<--------> Data In (RD)      A
  6       6       DSR           <--------> RTS               E
  4      20       DTR           <--------> CTS               D


Some PC's need Pins 8 and 4 shorted.


  9-Pin D-Type (Male) Computer

___________________
\  1  2  3  4  5  /
 \   6  7  8  9  /
  \-------------/
 

    25-Pin D-Type (Male) Computer

\  1  2  3  4  5  6  7  8  9  10 11 12 /
 \  15 16 17 18 19 20 21 22 23 24 25 /
  \---------------------------------/
 


Remember on the The BBC the domino (5 pin DIN) plug can be inserted
TWO ways, which effectivly swaps Data In with CTS and RTS with
Data Out. 


Regards
       Elmo
| Keith 'Elmo' Eldridge | elmo@...              73064.1164@...            |
|                       |     Keith.Eldridge@...                          |
|         Opsis         | 40 Lindsay Ave, West Point, Manchester, M19 2AG |
|  'Computer Training'  |         Phone & Fax : (0161) 225 1048        UK |