private void browseThermoTree()
        {
            Opc.ItemIdentifier itemId = null;
            BrowseFilters filters = new BrowseFilters() { BrowseFilter = browseFilter.all };
            BrowsePosition position;
 
            // initialise item array to hold a single item
            Opc.Da.Item[] items = new Opc.Da.Item[1];
            for (int i = 0; i < items.Length; i++)
                items[i] = new Opc.Da.Item();
 
            // initialise url to local server
            Opc.URL url = new Opc.URL("opcda://" + "localhost" + "/" + "EGS.OPCServer.Line10.1");
            _server = new Opc.Da.Server(_fact, null);
 
            try
            {
                //  try to connect to the server
                _server.Connect(url, new Opc.ConnectData(new System.Net.NetworkCredential()));
 
                if (_server.IsConnected)
                {
                    // browse the server for all the items - 295 elements returned
                    BrowseElement[] elements = _server.Browse(itemId, filters, out position);
 
                    // of the 295 elements returned, pick the first one to read, ItemName is FRAME1\\Heartbeat
                    items[0].ItemName = elements[0].ItemName;
 
                    // read call causes an exception E_FAIL IOPCSyncIO.Read
                    itemValueResults = _server.Read(items);
 
                    // never get to this code due to exception
                    for (int i = 0; i < itemValueResults.Length; i++)
                    {
                        if (itemValueResults[i].Value != null)
                            tbDebug.AppendText(itemValueResults[i].Value.ToString() + "\n");
                        else
                            tbDebug.AppendText("Item not valid\n");
                    }
 
                    tbDebug.AppendText("\n");
 
                    _server.Disconnect();
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }