>>>I want to write data to lpt1 port to control PCU customer display.
>>>The only way to do using vfp native commands is "run copy fn lpt1"
>>>but this is too low for disply control.
>>>
>>>So the only possibility is to use API.
>>>
>>>I tried the following command:
>>>
>>>declare short CreateFile in win32api
>>> ...
>>>secattr = chr(12) + repl( chr(0), 11 )
>>>lcPORT = 'COM1'+chr(0)
>>>I= createfile( @lcport, 0 , 0, @secattr, 3,0, 0 )
>>>J=GETLASTERRor()
>>>
>>>But createfile return -1 and getlasterror() returns
>>>87 ERROR_INVALID_PARAMETER!
>>>
>>I'm a bit confused. You mention LPT1 (Parrelel Port), but the code in your example shows COM1 (Serial Port). I would guess that the low level file functions (FOPEN(), etc.) map directly to the Win API functions for these tasks. Because of this, I don't think that you can open the printer ports using CreateFile(), if FOPEN() fails.
>>
>>Further, most of the information on this subject that I've read separates communications (modems, etc.) from printing. So my guess is that you can't do this with CreateFile().
>
>I'm sorry. The line above shoult be
>
>lcPORT = 'lpt1'+chr(0)
>
>George, which API calls must be used to send data directly to lpt port?

First, you have to use OpenPrinter() to get a handle, then I'd tried sending the data via WritePrinter() and finally ClosePrinter(). I haven't tested any of these, but they're what I'd look at if I were going to try this. I haven't tested this, but there's a starting point.

hth,