// Display progress during acquisition
procedure TfrmMain.ImageEnIO1Progress(Sender: TObject; per: Integer);
const
  Show_Images_As_Acquired = True;
var
  LastError: Integer;
begin
  LastError := ImageEnMView1.MIO.TwainParams.LastError;
  showMessage(inttostr(LastError));

  ProgressBar1.Position := per;

function IETW_DS(var grec: tgrec; dg: TW_UINT32; dat: TW_UINT16; msg: TW_UINT16; pd: TW_MEMREF): boolean;
var
  fpExpDisabler: TIEFPExceptionsDisabler;
begin
  with grec do
  begin
    rc := TWRC_FAILURE;
    if (@DSM_Entry <> nil) then
    begin
      try
        fpExpDisabler := TIEFPExceptionsDisabler.Create();
        try
          rc := DSM_Entry(@AppId, @SourceId, dg, dat, msg, pd);
        finally
          fpExpDisabler.Free();
        end;
        if (rc <> TWRC_SUCCESS) and (rc <> TWRC_XFERDONE) and (dat <> DAT_EVENT) and assigned(TWParams) then
        begin
          TWParams.LastError    := rc;
          TWParams.LastErrorStr := ResultToStr(rc);
          LogWrite(Format('IETW_DS : %s', [TWParams.LastErrorStr]));
        end;
      except
        on E:Exception do
        begin
          LogWrite(Format('IETW_DS : Exception -> %s', [E.Message]));
          driverException := true;
        end;
      end;
    end;
    result := (rc = TWRC_SUCCESS);
  end;
end;