My laptop doesn't have a parallel port so I purchased a USB to parallel convertor. I wrote a program which sends data to the parallel port to turn on some LEDS and it works ok on a PC with a built in parallel port but it wont work on my laptop with the USB to Parallel convertor. I used the delphi parallel port driver inpout32.dll which I found at http://www.sixca.com/eng/articles/pardel/index.html

Typical use is shown below....

procedure TForm1.Button1Click(Sender: TObject);
begin
Out32($378,$0f); //send $0f to parallel port
end;

Does anyone know why the above code will not work with a USB to parallel convertor?

What brand is the USB Parallel converter?
I am just taking a guess here but it could be that the converter is using 0x278 for the memory location of the port and not 0x378 . Look at the manual and see what location the port is using.
Let me know if you can't find the correct memory address.

It's a ARCHEON’s USB-Parallel Printer Cable and the manual doesn't say what address it uses. I did try 0x278 but still no joy.

Yes same i don't see that address to my laptop using usb to paralel can explain for more? thanks