Re: Help with null modem

[Rubywand <rubywand@swbell.net>]

Ronald Clark writes ...
> 
> I am trying to transfer files from the win to the GS
> but I can send for the win to the GS but I can send from the GS to the > win I am using Proterm 3.1 and the pin out are
> 1-1 2-3 3-2 4-5 5-4 6-20 7-7 8-20

 ....


     A NULL modem is, typically, two 25-pin female sockets (call them
"A" and "B") wired back-to-back as follows ...

 Socket-A  Socket-B

    1      -> 1
    2      -> 3
    3      -> 2
    4 & 5  -> 8
    6 & 22 -> 20
    7      -> 7
    8      -> 4 & 5
   20      -> 6 & 22


     If you can find a couple old-style DIN-25 plug casings, the sockets
can be mounted and the casings can be glue-gunned together to make a
nice compact unit.

     For GS-PC (or Mac, etc.) transfers, you plug the modem cable from
the GS into one side of the NULL modem and the modem cable from the PC
into the other side. If the PC has a 9-pin serial port connector, use a
9-to-25 adaptor cable to connect to the NULL modem. Similarly, if the
Mac cable has a special connector, use a converter to a  male DB-25
connector for plugging into the NULL modem.


     If you want to run at 9600 baud or above, something else to check
is that you are using a "hi-speed" (hardware handshaking) modem cable.
The info below comes from a post by Tae Song (White Wolf). It matches
the recommended cable described in the Spectrum manual:


View is looking into the connector at the pins.

Male Mini-Din 8             RS-232 Male DB-25

   6 7 8           01 02 03 04 05 06 07 08 09 10 11 12 13
   3 4 5            14 15 16 17 18 19 20 21 22 23 24 25
    1 2



DIN-8    DB-25     Signal Discription

  3        2        TD  (Transmit Data)
  5        3        RD  (Receive Data)
  4,8      7        GND (Ground)
  2        5        CTS (Clear to Send)
  1        4,20     RTS (Ready to Send) (20 = Data Term Rdy, DTR)
  7        8        DCD (Data Carrier Dectect)



     Mainly, I use Spectrum; but, a ProTerm 3.1 setup should be very
similar. For example, with the above stuff, you would want to turn ON
Hardware Handshaking. Also, usually, Binary Up should be OFF and Binary
Down should be ON.



Rubywand