The procedure get_heapid has one IN and one OUT parameter. Point out on adParamInput and adParamOutput;
         

 function TPxBank.GetID(strHeap:WideString; out id: integer): HResult;
 var
   cmd: _Command;
   ra: OleVariant;
 begin
   Result := S_Ok;
   try
     cmd := CoCommand.Create;
     cmd.Set_ActiveConnection(GetConnection);
     cmd.CommandText := 'execute procedure get_heapid(?)';

     cmd.Parameters.Append(cmd.CreateParameter('heap', adVarChar, adParamInput, length(strHeap), strHeap));
     cmd.Parameters.Append(cmd.CreateParameter('id', adInteger, adParamOutput, -1, 0));
     cmd.Execute(ra, EmptyParam, 0);
     id := cmd.Parameters.Item['ID'].Value;
     SetComplete;
   except
     on E: Exception do begin
       Result := E_FAIL;
       SetAbort;
       raise;
     end;
   end;
 end;