Creating string pointer for dll

Question

I'm trying to use a DLL to access a Reflective memory board using LV6.i
under Windows2000. The first call to the DLL takes a pointer to a string
that contains the device name and it returns a handle to that has to be
used in all other calls.
The syntax is - RFMHANDLE rfmOpen( char devPath );
The example in the documentation is;
RFMHANDLE rh;
char *devPath = "\\\\.\\RFM1"; This is the
W2000 name for the board
if( (rh = rfmOpen( devPath ) ) == NULL ){
exit(1);
All the other calls pass the handle rh as the calling parameter.
My question is how do I create the string pointer devPath?
Ed

Answer 1

Ed,
I'm a Labview DLL rookie but I think all you have to do is in the DLL
configure define the arg Type as a "String" and the String Format as a "C
String Pointer". Then when you wire that terminal up, just connect it to
Sting Constant or Control. Then just pass that argument the device name
string. Labview will take care of actually passing the that string pointer
value to the DLL.
I just done something similar with an array of 16 bytes. I am supposed to
pass the function the pointer to the array and it will change the data in
that array. I defined the arg as Type "Array" of Data Type "Unsigned 8-bit
Integer", Dimension "1", and Array Format as an "Array Data Pointer". I
then connected that terminal to the Build Array function of 16 bytes. The
output terminal
directly accross from that input terminal was connected to
an array indicator. When I run the VI the data bytes were changed as
expected.
The point is that I never really had to deal with the pointer directly. So
you don't have to create the string pointer, just create the string and
connect it to the terminal defined as a string.
- David
Ed Bogart wrote:
> I'm trying to use a DLL to access a Reflective memory board using LV6.i
> under Windows2000. The first call to the DLL takes a pointer to a string
> that contains the device name and it returns a handle to that has to be
> used in all other calls.
>
> The syntax is - RFMHANDLE rfmOpen( char devPath );
>
> The example in the documentation is;
> RFMHANDLE rh;
> char *devPath = "\\\\.\\RFM1"; This is the
> W2000 name for the board
>
> if( (rh = rfmOpen( devPath ) ) == NULL ){
> ....
> exit(1);
> }
>
> All the other calls pass the handle rh as the calling paramete
r.
>
> My question is how do I create the string pointer devPath?
>
> Ed