Russ Button <button@idiom.com> wrote:
: I've got a Sparc 10 workstation.  The serial port is a DB25 connector
: that is both serial port A and serial port B.  I need to fabricate
: a splitter cable for it and need documentation for the pin-out on
: that connector.  

: I want to run a null modem from serial port B to the console of a
: Sun server and use tip to connect to the Sun server.  I know that
: for serial port A, you use cross pins 2 and 3 and run pin 7 straight
: through.  What are the pins to cross for serial port B?  Do you still
: use pin 7 for the straight through for serial port B?  Or is there
: a different pin for the purpose for serial port B?

I found what looks to be the docs I'm looking for at

http://www.sunhelp.org/faq/sunref2.html

But I'm a bit confused about the terminology.

I need to fabricate a null modem line that goes from serial port B on
an SS 10 to serial port A on a Sun E250/E450...  the standard serial
port A.

From the doc above we have...

**************************************************************************
+ DB25 A/B serial ports on SPARCstation SLC, ELC, others?

        1  unused       9  unused       17 A-RxC (receive clock)
        2  A-TxD        10 unused       18 unused
        3  A-RxD        11 unused       19 B-RTS
        4  A-RTS        12 B-DCD        20 A-DTR
        5  A-CTS        13 B-CTS        21 unused
        6  A-DSR        14 B-TxD        22 unused
        7  A&B-GND      15 A-TxC in (?) 23 unused
        8  A-DCD        16 B-RxD        24 A-TxC out (transmit clock out)
                                        25 unused

   Note that only port A has full modem control.

+ DB25 A/B serial ports on SPARCstation LX, SPARCclassic, and
  SPARCstation 10, others?

   As for the SLC/ELC, but with additional signals for the B port:

        11 B-DTR        18 B-TxC in     25 B-TxC out
**************************************************************************

I know that with a normal DB 25 to DB 25, we'd have


serial port B                                                  serial port A
============================================================================
pin 2  A-TxD---------------\   /-------------------------------pin 2  A-TxD
                            \ /
                             \
                            / \  
pin 3  A-RxD---------------/   \-------------------------------pin 3  A-RxD

pin 7  A&B-GND-------------------------------------------------pin 7  A&B-GND



Then with the above docs, would the SS10 to normal DB 25 serial port A,
would it be...

SS10                                                           Sun Server
serial port B                                                  serial port A
============================================================================
pin 14 A-TxD---------------\   /-------------------------------pin 2  A-TxD
                            \ /
                             \
                            / \
pin 16 A-RxD---------------/   \-------------------------------pin 3  A-RxD

pin 7  A&B-GND-------------------------------------------------pin 7  A&B-GND