dgErrorNumber enum | QSYS API Reference Guide

  AdgConnection db = new AdgConnection("*Public/DG NET Local");
  FileAdapter dbFile = new FileAdapter(db, "*Libl/CMASTNEWL1", "CMMASTERL1");
  dbFile.AccessMode = AccessMode.Read;

  AdgDataSet myDS = null;
  try
  {
      dbFile.OpenNewAdgDataSet(out myDS);
  }
  catch(dgException dgEx)
  {
      /* There are many reasons why opening a file can fail. Here, we
       * catch some of the more general ones. */
      if (dgEx.Error == dgErrorNumber.dgEmMNOTFND)
          MessageBox.Show("Member " + dbFile.MemberName + " not found!", "Error opening file");
      else if (dgEx.Error == dgErrorNumber.dgEmFNOTFND)
          MessageBox.Show("File " + dbFile.FileName + " not found!", "Error opening file");
      else
          MessageBox.Show(dgEx.Message, "Error opening file");
          //Exit procedure here.
  }

  /* Do some action here. */

  dbFile.Close();
  db.Close();