April 17, 1990


    While setting up the RBBS-PC software for the first time, I
ran into certain difficulties which required a great deal of
testing online to another computer (instead of through local
mode).  My problem was that there were seldom convenient times
for me to have friends keep dialing in (and getting knocked off!)
while I checked various parameters and made changes.  Clearly the
answer was to hook up another computer locally, though there was
no information directly available on how to do this for the RBBS
software.  A little trial and error with a breakout box sufficed,
however, and I would like to pass on the fruits of my endeavors
to those who might find it useful.

    The particular configuration I set up was between my IBM
PC/AT clone (with 9-pin serial port), and a non-IBM-compatible PC
(using a 25-pin serial port).  I have included diagrams that
should cover both 9-to-9 pin and 9-to-25 pin configurations.

    First off, there are two parameters that must be changed in
order for the setup to work properly.  They are: the number of
rings that RBBS answers on; and whether you are using a "dumb"
auto-answer modem.  In CONFIG version 17.x, these are parameters
224 and 230, respectively (check the documentation for earlier
versions to find out which parameter numbers correspond to these
selections).  Parameter 224 must be set to 0, so that RBBS simply
responds whenever it receives a Carrier Detect signal, instead of
waiting for the phone to ring.  Parameter 230 must be set to
"Yes", so that RBBS does not issue any modem commands.

    IMPORTANT!!: After constructing the appropriate "null-modem"
cable from the following diagrams, hook up the end that goes to
the RBBS "Host" computer, but leave the end that attaches to the
"remote" computer unattached until you have started up the RBBS
software, and it gives the indication "WAITING FOR CARRIER".
Then start up the terminal software on your "remote" computer and
plug in that end of the cable - you should now come online to
RBBS.  When you logoff of RBBS from the "remote" computer,
disconnect the "remote" end of the null-modem cable, or RBBS will
not recycle properly.

    NOTE:  If you attach both ends of the null-modem cable before
starting up the RBBS software, RBBS will continually recycle,
showing nothing but a blank screen.  Disconnect the "remote" end
of the cable and wait for RBBS to recycle before continuing.

    NOTE: If you are adventurous, you can wire a switch into the
wire that goes to the DTR signal on the "remote" end, and use the
switch to connect or disconnect the "remote" computer from RBBS
instead of having to plug and unplug the cable.

    Feel free to leave me a message on the Your Place BBS with
any comments or questions.

Regards,

Bob Hampton
Sysop-to-be
S-3 Tech BBS (coming soon!)






                    NULL MODEM CABLE FOR RBBS


                           DB9S-to-DB9S
                          ==============

                   RD  2------------------3  TD

                   TD  3------------------2  RD

                  GND  5------------------5  GND

                                      +---1  DCD
                                      !
                  DTR  4--------------+---6  DSR
                                      !
                                      +---8  CTS

                  DCD  1---+
                           !
                  DSR  6---+--------------4  DTR
                           !
                  CTS  8---+





                          DB9S-to-DB25P
                         ===============

                   RD  2------------------2  TD

                   TD  3------------------3  RD

                  GND  5------------------7  GND

                                      +---5  CTS
                                      !
                  DTR  4--------------+---6  DRS
                                      !
                                      +---8  DCD

                  DCD  1---+
                           !
                  DSR  6---+-------------20  DTR
                           !
                  CTS  8---+