<hamid.sarab@gmail.com> wrote in message 
news:1106656033.980940.28080@z14g2000cwz.googlegroups.com...
> hi
> thats your kindness
> we want to draw a shape such az circle with external device that
> connect to computer by parallel or serail port
> The only thing that we need is process of shape by matlab & send out of
> edge position

You will have to be more specific to get good responses.

The "external device" could be a lot of things.
I will assume that it is an x-y device such as a mouse with a crosshair 
attached to it - so you only need to interpret what the mouse is doing in x 
and in y - the same as is done with any number of computer programs.

Next step: how to get from serial mouse to Matlab?
Perhaps a simple mouse position-reading program in C/C++ that interfaces to 
Matlab?
That might get rid of any low-level serial port reading requirements.

Shape and edge position are two different things, aren't they?
Did you have some processing or processing requirement specifically in mind?

Does this have to be in real time or might some interim program do a good 
part of the job for you?

Fred 

hi
thats your kindness
we want to draw a shape such az circle with external device that
connect to computer by parallel or serail port
The only thing that we need is process of shape by matlab & send out of
edge position 
tanks