>Thaks for Your answer, I already did it but no luck. Of course I put sc.dll.lib in Project Settings
>I receive
>"fll_20 error LNK2019: unresolved external symbol "struct SGlobalMemorytag * __fastcall Init_scom(int)" (?Init_scom@@YIPAUSGlobalMemorytag@@H@Z) referenced in function "void __fastcall InitCom(struct ParamBlk *)" (?InitCom@@YIXPAUParamBlk@@@Z)"
>
>as a linker error message.
>
>Here my portion of code:
>

>
>*** sc_dll.h
>typedef struct SGlobalMemorytag
>{
>....
>)SGlobalMemorytag
>
>SGlobalMemorytag* Init_scom(int);
>void Close_scom();
>void Timer_proc();
>
>
>*** My main program
>
>#include "sc.dll.h"
>#define MAX_CON 20
>
>SGlobalMemorytag* sg
>
>
>
>void InitCom(ParamBlk *parm)
>{
>   long i = p0.ev_long-1;
>   sg = Init_scom(i);
>   if(sg == NULL)
>      _RetLogical(false);
>   else
>   {
>     for(int i=0;i<MAX_CON;i++)
>         sg->installed[i] = 0;						
>   _RetLogical(true);
>   }
>}
>

>
>TIA

Borislav,

First, I want to make sure that it is a typo in your code, is it ?

#include "sc.dll.h"     // should this be sc_dll.h ?

If it is a typo, try to add extern "C"

#include "sc_dll.h"
#define MAX_CON 20

extern "C"     // Assume C declarations for C++
{

   // put all of your prototype/declarations for the external header file here

   SGlobalMemorytag* sg

}              // End of extern "C"

Try to compile again

Update:
You might also need to put extern "C" in your header file (sc_dll.h). If there is another "#include" in the header, put it right after the "#include". To make your header be safe ( can compile with C and C++ ) put it like this:

#ifdef __cplusplus
extern "C" {
#endif

typedef struct SGlobalMemorytag
{
....
)SGlobalMemorytag

SGlobalMemorytag* Init_scom(int);
void Close_scom();
void Timer_proc();

#ifdef __cplusplus
}
#endif