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Jim Sawyer · Guest

I have generated the following tiny program: (the procedure ClosePort
is in the DLL and just closes a port, provided it is open):

unit Recv;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, RzButton;

type
TForm1 = class(TForm)
SendButton: TRzBitBtn;
CloseButton: TRzBitBtn;
procedure SendButtonClick(Sender: TObject);
procedure CloseButtonClick(Sender: TObject);

private
{ Private declarations }
public
{ Public declarations }
end;

procedure ClosePort; stdcall; external 'IDXVETLAB.DLL';

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.SendButtonClick(Sender: TObject);
begin
ClosePort;
end;

procedure TForm1.CloseButtonClick(Sender: TObject);
begin
Close;
end;

end.

when I try to run the program, I get the error

The procedure entry point ClosePort could not be located in
the dynamic link library IDXVETLAB.DLL.

I think it's finding the DLL because when it I change the reference
to a ficticious name, it tells me it can't find it. So I conclude that
I'm not giving it some instruction related to where in the DLL the
procedure ClosePort is located.

I'm new at this DLL use thing, so any help will be appreciated. I've
been fighting this for a couple of weeks now.

Jim Sawyer · Guest

Leon - I'm now working with the below bit of code:

unit Recv;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, RzButton;

type
TForm1 = class(TForm)
TestButton: TRzBitBtn;
CloseButton: TRzBitBtn;
procedure TestButtonClick(Sender: TObject);
procedure CloseButtonClick(Sender: TObject);

private
{ Private declarations }
public
{ Public declarations }
end;

procedure ClosePort; stdcall; external 'IDXVETLAB.DLL' index 1;

function OpenPort( sPort: String ): Integer; stdcall; external
'IDXVETLAB.DLL' index 1;

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.TestButtonClick(Sender: TObject);
var
nPort: Integer;
begin
nPort := OpenPort( 'COM1' );
ClosePort;
ShowMessage( IntToStr( nPort ) );
end;

procedure TForm1.CloseButtonClick(Sender: TObject);
begin
Close;
end;

end.

Adding the "index 1" to the end of each declaration made
it work... sort of. Here is what happens. I breakpoint the
debugger on the

nPort := OpenPort( 'COM1' );

line. The unit runs and I depress the test button and the
debugger breaks. I then step past the next three lines and
both the function and the procedure execute. Then the
"ShowMessage" box displays 0 . I "enter" and the
execution stops on the

end;

line. I step one more time and the the error message

Receive.exe faulted with message: 'privileged
instruction at 0x0012fc3c.' Process stopped.
Use step or run to continue.

Questions:
1. What does the "INDEX 1" contribute? I added that
only because I saw it on an example while searching
good ol' Google.
2. What is the error code and why does it occur only
when the 'OnClick' code ends?

Also, the spec for the DLL that I have specifies some
properties such as

Destingation Property

syntax:
Object.Destination [ = Value ]
where Value is the ASCII value of the port number.

3. How do I use such properties as this?

Thanks,
Jim

"Leon Zandman" <NOSPAMusenet (AT) wirwar (DOT) com> wrote

Jim Sawyer · Guest

Leon -

I'm now trying to use the code

Jim Sawyer · Guest

Leon -

I am now trying the code below:

unit Recv;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, RzButton;

type
TForm1 = class(TForm)
TestButton: TRzBitBtn;
CloseButton: TRzBitBtn;
procedure TestButtonClick(Sender: TObject);
procedure CloseButtonClick(Sender: TObject);

private
{ Private declarations }
public
{ Public declarations }
end;

TAddOpenPort = function( sPort: String ): Integer; stdcall;
function OpenPort( sPort: String ): Integer; stdcall; external
'IDXVETLAB.DLL';

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.TestButtonClick(Sender: TObject);
var
hLib: HMODULE;
fOpenPort: TAddOpenPort;
i: Integer;
begin
hLib := LoadLibrary('IDXVETLAB.DLL');
if ( hLib <> 0 ) then
begin
@fOpenPort := GetProcAddress( hLib, 'OpenPort' );
if ( @fOpenPort <> NIL ) then
i := fOpenPort( 'COM1' )
else
MessageDlg( 'Can'' find OpenPort function!', mtError, [mbOK], 0 );

FreeLibrary( hLib );
end
else
MessageDlg( 'Can''t load IDXVETLAB.DLL', mtError, [mbOK], 0 );
end;

procedure TForm1.CloseButtonClick(Sender: TObject);
begin
Close;
end;

end.

Since, on execution, I get the message

Can't find OpenPort function!

I conclude that the 'IDXVETLAB.DLL' is successfully loading, but
that the OpenPort function can't be found. Do you see anything
wrong? I have the DLL user's spec and also am in daily phone
contact with the writer of the DLL, so I'm sure the OpenPort
function is in the DLL, that it has one string argument and
returns an integer value. The DLL writer is expert in C++ (DLL's
language, VB, etc., but not Delphi, so he's lost.

Can you see anything wrong?

Thanks for your patience...

Jim Sawyer
Texas

Jim Sawyer · Guest

Leon -

Removing the @ gives the same result (Can't find OpenPort function!).

For whatever it's worth, when I monitor the value of fOpenPort during
execution, the debugger gives the message 'Not enough parameters'. The
value @fOpenPort is NIL.

I've also tried replacing "stdcall" with

register
pascal
cdecl
safecall

The result stays the same in all cases.

????
Jim Sawyer

"Leon Zandman" <NOSPAMusenet (AT) wirwar (DOT) com> wrote

Jim Sawyer · Guest

Leon -

To avoid the difficulty of passing a string to C++, I changed the code to
use a procedure in the Dll, as follows:

unit Recv;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, RzButton;

type
TForm1 = class(TForm)
TestButton: TRzBitBtn;
CloseButton: TRzBitBtn;
procedure TestButtonClick(Sender: TObject);
procedure CloseButtonClick(Sender: TObject);

private
{ Private declarations }
public
{ Public declarations }
end;

TAddClosePortFunction = procedure; stdcall;
procedure ClosePort; stdcall; external 'IDXVETLAB.DLL';

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.TestButtonClick(Sender: TObject);
var
hLib: HMODULE;
fClosePort: TAddClosePortFunction;
begin
hLib := LoadLibrary('IDXVETLAB.DLL');
if ( hLib <> 0 ) then
begin
@fClosePort := GetProcAddress( hLib, 'ClosePort' );
if ( @fClosePort <> NIL ) then
fClosePort
else
MessageDlg( 'Can'' find ClosePort procedure!', mtError, [mbOK], 0 );

FreeLibrary( hLib );
end
else
MessageDlg( 'Can''t load IDXVETLAB.DLL', mtError, [mbOK], 0 );
end;

procedure TForm1.CloseButtonClick(Sender: TObject);
begin
Close;
end;

end.

I still get the

Can't find ClosePort procedure!

error with both the above code and after changing the

@fClosePort := GetProcAddress( hLib, 'ClosePort' )

to

fClosePort := GetProcAddress( hLib, 'ClosePort' );

Thanks for all your help!
Jim Sawyer

"Leon Zandman" <NOSPAMusenet (AT) wirwar (DOT) com> wrote

Jim Sawyer · Guest

To make sure I'm not missing something, here is the way the DLL spec defines the ClosePort procedure and a PortInquiry function. Am I missing something?

ClosePort Subroutine

Closes the currently opened port. If no port has been opened, the command is ignored.

.. Syntax

Object.ClosePort

PortInquiry Function

Sends a port inquiry to the destination device and returns an integer representing a member of

the enumeration SND_STATUS. Only a VetTest or a VetStation should send a PortInquiry

message.

.. Syntax

Object.PortInquiry

Jim Sawyer · Guest

To make sure I'm not missing something, here is the way the DLL spec
defines the ClosePort procedure and a PortInquiry function. Am I missing
something?

Jim Sawyer

ClosePort Subroutine

Closes the currently opened port. If no port has been opened, the command is
ignored.

.. Syntax

Object.ClosePort

PortInquiry Function

Sends a port inquiry to the destination device and returns an integer
representing a member of

the enumeration SND_STATUS. Only a VetTest or a VetStation should send a
PortInquiry

message.

.. Syntax

Object.PortInquiry

Jim Sawyer · Guest

Leon -

I read your last post, and immediately ran TDump on the DLL. This is what
it yielded:

Export ord:0001 = 'DLLConUnloadNow'
Export ord:0002 = 'DLLGetClassObject'
Export ord:0003 = 'DLLRegisterServer'
Export ord:0004 = 'DLLUnregisterServer'

That is all. There is no mention of any of the routines or properties, such
as the
procedure "ClosePort" that are contained in the DLL spec. And the spec does
not
mention any of the above four routines.

It seems that this DLL is not merely a collection of routines for me to use.
Instead,
it seems to me to be a "little engine" to interface with the com port and
the data from
the the lab equipment which comes through that com port, and to present it
for my
use in a "cleaned up" form. Am I thinking correctly? If so, I have no idea
how to
implement this thing. Do I understand from your last post that Delphi can't
use
such a DLL if it is written in C++? Am I up the proverbial creek?

Thanks
Jim

Jim Sawyer · Guest

Leon! My new best friend! We (meaning you) did it! It is working! I just
have to learn the DLL now. You have spent a lot of time helping, and you
have given very clear explanations and instruction throughout. I owe you
one, friend.

Jim Sawyer

"Leon Zandman" <NOSPAMusenet (AT) wirwar (DOT) com> wrote