According to BertieBigBollox@gmail.com <BertieBigBollox@gmail.com>:
> OK. So let me get this right....
>
> No keyboard attached to sun machine.
>
> DB25 plugged into Serial A on sun machine.
> DB9 plugged into serial port of PC.
> RJ45 cable connecting the two. (straight thru or crossover ???)

Hmm ... do you have any idea how the pins of the connectors are
mapped to the RJ-45 pins? I'm sure that I have at least three or four
versions floating around here. It all depends on who wired the
connectors and for what purpose.

What is *important* is which pins from the DB-25 are connected
to which pins on the DB-9 (really DA-9 I think). And beware that DEC
and PCs tend to use male DB-25 or DA-9 connectors for DTE (terminal
wired) serial ports, while Sun uses a female DB-25 for the same purpose,
so you need certain pins crossed over.

I tend to start with a breakout box (two DB-25 connectors, LEDs
to monitor each side, switches to connect straight across (e.g. pin 2 to
pin 2), and provisions for jumper wires to set up any other crossover
connections. I start out with the switches open (other than pin 7 (the
data ground), and observe whether both sides are trying to drive the
same pin. If so, I set up a pair of jumper wires to interchange pins 2
and 3 between the sides. Then I go on to figure out what others may
need to be present and crossed over.

> Hyperterm on PC. 9600-8-N-1
>
> Is that right so far ???

No experience with Hyperterm, but the settings look right.

But until you know what the wiring in your connectors happens to
be, having the right settings on the terminal program won't get you
much. The DTE/DCE question is whether one end is wired as DTE (Data
Terminal Equipment -- in other words like a stand-alone terminal), or as
DCE (Data Communications Equipment -- a modem -- which is what the
RS-232 standard was intended for -- communications between terminals (or
computers pretending to be terminals) and modems. All other uses were
added after the standard got defined. And then the PC started coming
out with 9-pin subsets of the full connector.

I think that someone else has already posted a URL pointing to
the proper pinout, so I won't bother typing all of that in from scratch.

Good Luck,
DoN.
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