Hi all,

I think I know what the problem is with the serial cable connection
between Linux and Windows. Under windows, there is something called
DTR and RTS which are normally switched on:

C:\>mode COM1

Status for device COM1:
-----------------------
Baud: 2400
Parity: None
Data Bits: 8
Stop Bits: 1
Timeout: OFF
XON/XOFF: OFF
CTS handshaking: OFF
DSR handshaking: OFF
DSR sensitivity: OFF
DTR circuit: ON
RTS circuit: ON

If you switch it off with

C:\>mode COM1 baud=2400 parity=n data=8 stop=1 to=off xon=off odsr=off
octs=off dtr=off rts=off idsr=off

and set up the serial port on the Linux side with

$ stty -F /dev/ttyS0 ispeed 2400 ospeed 2400 pass8

then they can communicate in both directions. It looks like we need
the opposite of this, i.e., enable DTR and RTS under Linux, but I
don't know yet how to do that. The man page for stty under Solaris
talks about dtrxoff and rtsxoff parameters, but these don't seem to be
available under Linux, and it's not clear if these are what we need,
either.

So, some progress, but we're not there yet. Just thought I'd share
it, in case anybody feels like helping out.

Ferenc