Classes
| Class | Description | |
|---|---|---|
 | BGBrowseTree | Available in the OPCDA.NET Professional Edition only. The server is browsed from a backgound thread and the browse result is returned in a TreeNode structure. A TreeView object can be passed to have this class directly display the browse result. In the default BrowseModeOneLevel mode only the root branch is browsed initally. Other branches are browsed when they are the first time selected in the TreeView. If also a ListView object is defined then the item of the selected branch are shown in the ListView controls. In the TreeView controls are only the branche shown in this case. The TreeNode Tag property is filled with a BrowseNodeInfo object that contains the information about the branch or item. For item nodes the BrowseElement object is filled with the item information. This includes the values of the properties defined to be read in the browse process. In the ListView browse mode the TreeNode structure contains only branches. In this case the BrowseNodeInfo object has a BrowseElement object for each item browsed in this branch. If the items are displayed in a ListView control then the Tag property of each ListViewItem is filled with a BrowseElement object the contains the information about the item. This class can only be used from classes that derive from System.Windows.Forms.Form. |
| BGCore | This class provides an interface to the OPC Core Components server enumerator (OpcEnum.exe). It's available in the OPCDA.NET Professional Edition only. OPC servers can be browsed on the local machine as well as networked machines. The browse requests are queued and handled in a background thread in order to prevent the application being blocked and unresponsive due to long execution times or long timeouts in case of COM or network issues. This class can only be used from classes that derive from System.Windows.Forms.Form. The completion notification with the browse result is synchronized with the user interface thread by internally calling Form.BeginInvoke() |
| BGDataBind | The BGDataBind class simplifies refresh handling. It's available in the OPCDA.NET Professional Edition only. DataBind subscriptions can be defined to bind OPC server items to Windows controls. Item value changes are written directly to properties of the bound Windows controls or user classes. This class executes the Subscribe handling in a background thread to prevent a blocking of the user interface thread. The data change callback handling is the same as with the OpcDataBind class. This class does not have a public constructor. Instances are created by calling the BGServer.AddDataBind method. This class can only be used from classes that derive from System.Windows.Forms.Form. The completion notification with the browse result is synchronized with the user interface thread by internally calling Form.BeginInvoke(). Each server access is timeout checked. On timeout the BGServer GeneralError handler is called to inform the user application. The server access thread may continue to wait for the server call to finish or timeout. Further requests are not being handled before this happens. |
| BGException | Exception uses in the BGxxx and DAxxx classes. The HRESULTS error code is accessible. |
| BGGroup | The BGGroup class handles the server access for data changed subscriptions and read/write operations. It's available in the OPCDA.NET Professional Edition only. The server access is executed in a background thread to prevent the user interface thread becoming unresponsive while waiting for a server response. For data change callbacks to happen the BGGroup has to be in active state. Read an Write operations are independent of the active state of the group. This class does not have a public constructor. Instances are created by calling the BGServer.AddGroup method. This class can only be used from classes that derive from System.Windows.Forms.Form. The completion notification with the results is synchronized with the user interface thread by internally calling Form.BeginInvoke(). Each server access is timeout checked. On timeout the BGServer GeneralError handler is called to inform the user application. The server access thread may continue to wait for the server call to finish or timeout. Further requests are not being handled before this happens. |
| BGServer | This class provides an interface to OpcServer class methods. It is available in the OPCDA.NET Professional Edition only. The requests are queued and handled in a background thread in order to prevent the application being blocked and being unresponsive due to long execution times or long timeouts in case of COM or network issues. This class can only be used from classes that derive from either the System.Windows.Forms.Form or the WPF System.Windows.Window classes. The completion notification with the browse result is synchronized with the user interface thread by internally calling BeginInvoke(). Each server access is timeout checked. On timeout the GeneralError handler is called to inform the user application. The server access thread may continue to wait for the server call to finish or timeout. Further requests are not being handled before this happens. |
| BrowseElement | BrowseElement class is returned from Browse The ItemID used in a Browse() call must be the value of ItemID returned with a browse element from a previous call to browse or an empty string (used to indicate a top level browse). The ItemID is a fully qualified descriptor for the element that can be used for further browsing and as an item id if IsItem is set. Note, that it is possible for a single element to be both an item and have children (e.g. complex data items). |
| BrowseNodeInfo | BGBrowseTree helper class with information about the node. |
| BrowseTree | The methods in this class simplify the browsing of the OPC server's address space. The browse result is returned in a TreeNode array that can directly be used with a Windows TreeView control. The server's address space organization is read and the browsing done accordingly. |
| DataBindEventData | Data object passed to the user data change event handler. |
| DataBindFormat | Holds the definitions how to transformn and format a value. |
| Images | Image list used in the BrowseTree methods to display icons in the TreeView and ListView dialogs. |
| ItemDefinition | |
| ItemList | |
| ItemListLoader | This class contains methods to read the ConfigBuilder created XML configuration file into memory. It's available in the OPCDA.NET Professional Edition only. The file can be embedded in the customization DLL or be a separate file. |
| ItemLists | |
| OpcDataBind | Class for automatic display and refresh of item values in Windows controls. |
| OpcGroup | The OpcGroup class contains the methods defined in the OPC DA group interface. The user does not need to construct OpcGroup objects. This is done internally in the OpcServer.AddGroup method. After the group is created the user needs to add a set of items to the group using the function AddItems. After that the added items can be accessed using the synchronous or asynchronous read / write functions of the group object. |
| OpcServer | The OpcServer class contains the functions as defined in the OPC Server object. The OPCServer object is the primary object that an OPC server exposes. It's most important function is AddGroup. All the item access functions are implemented in the OpcGroup class. The user can define a number of groups with different parameters such as the update rate. |
| RefreshEventArguments | Arguments passed to the user callback event handler. |
| RefreshGroup | Class with easy to use methods for asynchronous read/write functions and data change callbacks. Items can be accessed by their name without first creating a group. The items are added to the object internal data cache and to the associated OPC group. The object internal data cache is updated in the data changed callback handler and the application cna alwys read current data from the cache. The user can optionally install a user callback handler to get notified on value changes. The user callback handler is called after the internal cache is updated. The class is designed for the simple handling of individual items. The OpcGroup class is more efficient for handling multiple items, especially large number of items. |
| ShowBrowseTree | The OPC server is browsed using the BrowseTree class and the server address space with all branches and items is displayed in a TreeView control. |
| ShowBrowseTreeList | The methods in this class simplify the browsing and display of the OPC server's address space. The OPC server is browsed and the branches are displayed in a TreeView control. The items of the selected branch are displayed in a ListView control. Node images are displayed as shown in the picture. The user can select other images or supply his own ImageList. The whole hierarchical tree structure is browsed and displayed. In default mode, the server is browsed as needed, initially the root level and each branch when it is selected for the first time. This results in a short latency, even for servers with a large address space. The BrowseTreeList object's BowseModeOneLevel property can be set to false, to force browsing all levels in the first call. |
| ShutdownRequestEventArgs | Shutdown request handler IOPCShutdown::ShutdownRequest This method is provided by the client so that the server can request that the client disconnect from the server. The client should UnAdvise all connections, Remove all groups and release all interfaces. |
| Subscription | DataBind Subscription data for one item. |
| SyncIOGroup | Class with easy to use methods for synchronous read / write functions. Items can be accessed by their name without first creating a group. OPC DA V3 defines a similar function but the SyncIOGroup methods are implemented to work with V1,V2 and V3 servers. The class opens it's OPC group and adds items automatically at the first read or write function. The class is designed for the simple handling of individual items. The OpcGroup class is more efficient for handling multiple items, especially large number of items. |
| tlNodeInfo | TreeList node information for the link from the TreeNode branch to the TreeView with it's items. A reference to such an object is in the TreeNode Tag field. |
| XmlIO | This class contains methods to serialize and de-serialize OPCItemDef arrays. OPCItemDef arrays are used in the AddItems method to add items to an OPC group for read/write operations. Instead of creating all the OPCItemDef objects in the program, they can be defined in an XML file. The read method converts the file into an OPCItemDef array that can be directly used in the AddItems method call. |
Delegates
| Delegate | Description | |
|---|---|---|
 | DataBindCallbackErrorEventHandler | Callback handler that can be assigned to a subscription in place of a Windows control. The user can handle data change callbacks individually for each item. |
| DataBindCallbackErrorEventHandler2 | Callback handler that can be assigned to a subscription in place of a Windows control. The user can handle data change callbacks individually for each item. |
| DataBindCallbackUserHandler | DataBind value change callback handler for one item. If such a handler is defined for a subscription then this candler is called from the DataBind server callback handling in place of the default handling. The DataBind server callback handler does the Invoke handling for Windows thread synchronization and then calls this handler for each item in the server callback. The handler is true if the item is handled. Otherwise the default DataBind server callback handler will try to handle the callback for this item. |
| DataBindEventHandler | Callback handler that can be assigned to a subscription in place of a Windows control. The user can handle data change callbacks individually for each item. |
| OnBGBrowseServers | BGCore.BrowseServers completion notification. |
| OnBGGeneralError | The BGGeneralError handler is called when an error happens and the user did not pass a specific completion notification handler. |
| OnBGGeneralErrorExt | The BGGeneralError handler is called when an error happens and the user did not pass a specific completion notification handler. |
| OnBGGrpAddItems | BGGroup.AddItems completion notification. |
| OnBGGrpRead | BGGroup.Read completion notification. |
| OnBGGrpRemoved | BGGroup.Remove completion notification. |
| OnBGGrpRemoveItems | BGGroup.RemoveItems completion notification. |
| OnBGGrpWrite | BGGroup.Write completion notification. |
| OnBGRefresh | BGGroup.Refresh completion notification |
| OnBGSrvAddDataBind | BGServer.AddDataBind completion notification. |
| OnBGSrvAddGroup | BGServer.AddGroup completion notification. |
| OnBGSrvBrowse | BGServer.Browse completion notification. The specified branch is browsed according the filter selections and the result is in the nodes argument. |
| OnBGSrvConnected | BGServer.Connect completion notification. On successful competion the OPC server is connected and accessible through the BGServer object. |
| OnBGSrvDisconnected | BGServer.Disconnect completion notification. On successful competion the OPC server is disconnected. |
| OnBGSrvGetProperties | BGServer.BGSrvGetProperties completion notification. The selected properties of set of items is returned. |
| OnBGSrvGetStatus | BGServer.GetStatus completion notification. |
| OnBGSubscribe | BGDataBind.Subscribe completion notification. A subscription object is returned when the Subscribe was successful. This Subscription object allows access to methods of the DataBind object and even the underlying OpcGroup object. However, such an access is executed in the calling thread and may block the thread. |
| OnBrowseError | The OnBrowseError handler is called when an error happens in the server browse access from the TreeView mouse event handler. |
| OnBrowseFilter | Event handler method that is called before the OPC server BrowseItemIDs method is called to get the browse filters to be used. The application can specify filters that are appropriate for the current browse position. |
| RefreshEventHandler | Delegate of the user data change callback handler. This callback handler is called from the RefrshGroup callback handler after the item data is stored in the RefreshGroup internal data cache. |
| ShutdownRequestEventHandler | Shutdown request handler IOPCShutdown::ShutdownRequest This method is provided by the client so that the server can request that the client disconnect from the server. The client should UnAdvise all connections, Remove all groups and release all interfaces. |
Enumerations
| Enumeration | Description | |
|---|---|---|
 | browseFilter | An enumeration specifying which subset of browse elements to return. |
| ListType | |
| OPCServerTypes | This enumerator defines masks that specify the type of OPC server to be included in the browse result. Multiple values can be 'ored' to specify multiple types of OPC servers. |
| RefreshEventReason | Reasons why the user event handler is called. |
| UaTraceEvents | Trace event selection flags. |