create or alter procedure PR_CHECK_E
returns (
    USED_BY blob sub_type 1 segment size 80)
as
begin

  USED_BY = 'AAZAAZAA';

end;

create or alter procedure PR_CHECK_S
returns (
    USED_BY blob sub_type 1 segment size 80)
as
begin

  USED_BY = 'AAZAAZAA';

  SUSPEND;

end;

procedure TForm26.PrepareDBX;
begin
  with con1 do begin
    DriverName := 'Firebird';
    VendorLib := ExtractFileName(edtLFB.Text);
    LoginPrompt := False;

    Params.Values['DataBase'] := edtLDB.Text;

    Params.Add('ServerCharSet=WIN1251');
    Params.Add('lc_ctype=WIN1251');
    Params.Add('ISC_DPB_LC_CTYPE=WIN1251');
    Params.Add('SQLDialect=3'); // в предыдущем апдейте всех затащили

    Params.Values['User_Name'] := 'sysdba';
    Params.Values['Password'] := 'masterkey';
  end;

  con1.Open;

  con1.BeginTransaction;

  sp1.StoredProcName := 'PR_CHECK_E';
  sp2.StoredProcName := 'PR_CHECK_S';
  qr1.CommandText := 'select * from PR_CHECK_S';

  with sp1.Params do begin
    Clear;
    with AddParameter do begin
      Name := 'USED_BY';
      DataType := ftMemo;
      ParamType := ptOutput;
    end;
  end;

  qr1.Prepared := True;
  sp1.Prepared := True;
  sp2.Prepared := True;
end;

procedure TForm26.btn1Click(Sender: TObject);
begin
  with sp1 do begin
    ExecProc;
    ShowMessage('BLOB is: ' + Params[0].AsMemo);   //  Unknown error ISC 0
  end;
end;

procedure TForm26.btn2Click(Sender: TObject);
begin
  with sp2 do begin
    ExecProc;
    ShowMessage('BLOB is: ' + Params[0].AsMemo);   //  Invalid SQLDA structure
  end;
end;

procedure TForm26.btn3Click(Sender: TObject);
begin
  with qr1 do begin
    Open;
    try
      ShowMessage('BLOB is: ' + Fields[0].AsString);   //  CORRECT !!!
    finally
      Close;
    end;
  end;
end;