modular null modem pinout?

[julian macassey]

In article <433 at bigbroth.UUCP>, rk at bigbroth.UUCP (rohan kelley) writes:
> I'm trying to make a direct connect between a bell tech 386/25 and
> a 3b2/400.  The port on the 386 is an ace intelligent port board
> with 8 modular ports and on the 3b2 an enhanced port board.
> 
> I'm trying to construct a modular null modem cable.  This is the
> wiring diagram I've come up with, but haven't tried it yet.  Does
> anybody know if this is correct?
> 
> What I'm trying to say is:
> 
> G       1    to   1  G
> CTS     2 tie to  8 (plug)
> TDXO    3    to   5  RXDO
> DTR     4    to   6  DCD
> RXDO    5    to   3  TDXO
> DCD     6    to   4  DTR
> G       7    to   7  G
> RTS     8 tie to  2  (plug)
> 
> Neither the 386 or 3b2 have DSR (RS232 pin 6) which is usually tied to
> DTR.  Is it needed?

    What you have is not recognisable by me. Here is my RS-232 memory jogger 
file.

This may help some people.




        The Following are Various RS-232 Configurations.

 
 
                 DB-25 25 Pin Std Connector

Pin #
    1    Ground (Protective Ground) (Optional)
    2    Transmit Data (TXD)
    3    Receive Data  (RXD)
    4    Request To Send (RTS)
    5    Clear To Send (CTS)
    6    Data Set Ready (DSR)
    7    Ground (Signal Ground)
    8    Data Carrier Detect (DCD)
    9    + Testing Voltage
   10    - Testing Voltage
   11    No Connection
   12    Speed Mode Indication (CI)
   13    No Connection
   14    No Connection 
   15    Transmit Clock
   16    No Connection   
   17    Receive Clock
   18    Make Busy/Analog Loop (CN)    
   19    No Connection 
   20    Data Terminal Ready (DTR)
   21    Remote Digital Loop (RDL)   
   22    Ring Indicator (CE)
   23    Speed Select - Originate (CH) 
   24    Clock Out
   25    Test Mode (TM) 


                   DB-9 9 Pin Std Connector

Pin #
    1    Data Carrier Detect (DCD)
    2    Receive Data  (RXD)
    3    Transmit Data (TXD)
    4    Data Terminal Ready (DTR)
    5    Ground (GND)
    6    Data Set Ready (DSR)
    7    Request To Send (RTS)
    8    Clear To Send (CTS)
    9    Ring Indicator (CE) (RI)


                   DB9 to DB25 RS-232 Adaptor

DB9                DB25
1        DCD       8
2        RXD       3
3        TXD       2
4        DTR       20
5        GND       7
6        DSR       6
7        RTS       4
8        CTS       5
9        RI        22
SHELL    GND       1   


                     Standard RS-232 Cable

DB25               DB25
1        GND       1
2        TXD       2
3        RXD       3
4        RTS       4
5        CTS       5
6        DSR       6
7        GND       7
8        DCD       8
20       DTR       20
22     RING IND    22   (optional for answer modems)


Minimum RS-232 Cable (OK for some slow devices)

DB25               DB25
2        TXD       2
3        RXD       3
7        GND       7


                       Null Modem Simple

   (Using DB25 Connectors, see above for conversion to DB9)

This  Null  Modem connector  is  equivelent  to Black  Box  Model 
ME202B. It is used for conecting terminals to mainframes and UUCP 
connections.

    A         B
    1---------1
    2---------3
    3---------2
    7---------7    
   
    4|        4|        Note: | Means, pins are jumpered     
    5|        5|              together. - means pins wired   
                              to other connector.            
    6|        6| 
    8|        8|
   20|       20|      


                    Null Modem with control

(With  this cable, turning  off a terminal should  disconnect the 
line. recommended for use with terminals logged into mainframes.)

    A         B
    1---------1
    2---------3
    3---------2
    4---------5              Note: | Means, pins are jumpered   
    5---------4                    together. - means pins wired 
    7---------7                    to other connector.          
    
    6|-------20
    8|

   20--------|6
             |8


References: AT&T Unix-PC Communications Management Manual.
            Toshiba T1100P Users Manual
            EIA RS-232C (Oct 1969)
            Bell System Tech Ref Data Set 212A

                                    END
-- 
Julian Macassey, n6are  julian at bongo    ucla-an!denwa!bongo!julian
n6are at wb6ymh (Packet Radio) n6are.ampr.org [44.16.0.81] voice (213) 653-4495