[DUG] RFID - EAccess violation

[Karl Reynolds]

I don't know the API_PCDRead function. But there looks to be an error in
your code even if it works. You are passing bufferr (two 'r's) to the
function but referring to buffer (one 'r') afterwards, which wasn't used
(unless there's other code you didn't show). So you need to look at that.

That aside, for the bit leading up to the call, try something like:

var
  key, bufferr: PChar;
  keydata: string;
  buffdata: array[0..255] of char;
  ...
begin
 // Allocate a string of six consecutive $FFs
  keydata := #255#255#255#255#255#255;

 // Convert to a PChar, an easy way to avoid having to allocate memory
explicitly
  key := PChar(keydata);

// Once again avoid having to allocate memory explicitly
// Point bufferr at the address of an array of 256 characters
  bufferr := PChar(@buffdata);

  receive:=API_PCDRead(0,0,$00,10,1,key,bufferr);

  ...

Cheers,
Carl

On Thu, May 28, 2015 at 11:33 AM, Marshland Engineering <
marshland at marshland.co.nz> wrote:

> Thanks for the replies.
>
> this is the line
>
> >   receive:=API_PCDRead(0,0,$00,10,1,key,bufferr);
>
> I'm way out my depth with the workings of this function. I just do simple
> coding - A ex dBase3 programmer.
>
> I took the sample code that the RFID supplier gave, stripped off
> everything I
> didn't need other than the read line for RFID card and then copied the bits
> into my program which now crashes.
>
> I was wondering if the XPMENU call or something like that is interfering
> with
> other modules ?
>
> My debugging is limited to finding the line with the error.
>
> Both programs are run in Delphi 6, same machine and same environment.
>
> I can't find how to code this, where ever I put it, it crashes. - Expected
> expression but ARRAY found.
>
>    const
>      KEY = array[0..6] of Byte = ($FF,$FF,$FF,$FF,$FF,$FF,$00);
>
> Thanks Wallace.
>
>
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