[ILUG] Reverse engineering serial protocol

[Dale Dunlea]

> > Once you know the serial settings, maybe put a Linux 
> machine with twin 
> > serial ports between Windows and the touchscreen and write or find 
> > something on Linux to log and forward the data (avoids need 
> to makeup 
> > a cable.).
> 
> - but note that your forwarder may need to forward states of 
> handshake lines too. This applies particularly for mice 
> (serial mice, not that anyone uses them any more, tended to 
> need specific handshake lines asserted because they powered 
> themselves from them!) and modems, which may refuse to go 
> off-hook without a suitable handshake assertion, unless 
> explicitly configured otherwise (I forget the relevant Hayes 
> commands to set this option, but they are out there somewhere).

I borrowed an oscilloscope and started probing the RS232 cable. It's 
highly simplistic and doesn't do anything other than toggle the
transmit line. I now have a program that reports an XY coordinate 
every time the screen is touched. I've not puzzled it out entirely,
and there are still some bytes that I can't explain the purpose of,
but it's enough to make my program run. If I get the time, I may try
and develop a full-blown driver.

Thanks to all that helped

Dale.