If you are going to be hooking Sun consoles to your console server, you
may run into a problem:  The sun will halt whenever the cable is
unplugged.  It will also halt when the the console server is powered
off and on.  To prevent this we modified the wiring of our serial
cables at the end that attaches to the suns.

We have had this problem on all of our suns, except for the Sparc
Station 2.

The server can still be halted by generating a software line break,
which is can be done by sending an escape sequence to the console
server.  I think what happens in this case is the transmit line is
pulled low long enough for receive on the other end to be convinced a
break has occurred.  The resistor shown below passes just enough
current to keep the line high only when nothing else is going on.

WE WILL NOT BE HELD RESPONSIBLE FOR ANY DAMAGES CAUSED BY ATTEMPTING A
PARTIAL OR COMPLETE IMPLEMENTATION OF THIS MODIFICATION.
"WE" refers to The Ohio State University and specifically, the
employees of the CIS Department at Ohio State.

This is a diagram of the cable we use.

Sun file                                                     Console
Server                                                       Server
Side                                                         Side


   2  Tx  -------------------------  ------------------------- 2 Tx
                                   \/
                                   /\
   3  Rx  ------+------------------  ------------------------- 3 Rx
                |
                Z    4.7K resistor
                |
  25  -5v ------+                                             25 -5v

   7  GND ---------------------------------------------------- 7 GND

   4  RTS --+                                                  4 RTS
            |
   5  CTS --+                                                  5 CTS

   6  DSR --+                                                  6 DSR
            |
  20  DTR --+                                                 20 DTR