What is OPCDA.NET?
The OPCDA.NET is a .NET component for developing applications for OPC DA clients with C# or VB.NET. It provides high-quality OPC (C# or VB) OPC CLIENT applications for efficient development. The OPCDA.NET SDK supports 32- and 64-bit operations on all versions of Windows with .Net Framework 4.x. Many C# and VB.NET sample applications are provided with projects for Visual Studio 2010 through 2017. The OPCDA.NET SDK has a class structure with multiple layers. The user can choose the interface layer according to the requirements of the application and personal preferences.
- Server access controls reduce application code to a minimum. These invisible controls are configured in Visual Studio Designer and handle access to the OPC server with extensive error checking.
- QuickUse classes provide simple-to-use methods for data binding, item navigation, and read/write access to synchronous/asynchronous items. Thus, minimal knowledge of OPC is required.
- Methods of accessing the OPC DA V3 server. All defined (mandatory and optional) functions of OPC DA V3 can be accessed through methods that handle all data type conversions to/from .Net data types.
- Methods of access ing the OPC DA V2.05 server. All defined (mandatory and optional) functions of OPC DA V2.05 can be accessed through methods that handle all data type conversions to/from .Net data types.
Professional Edition offers features that improve application quality without increasing development effort.
- DAServer/DAGroup controls are configured in Visual Studio Designer and handle OPC Server access and callbacks.
- Background Server Access classes handle all server access in background threads and prevent the application from stopping responding due to a long DCOM communication time or a long server processing period, for example, to decrease access to the device.
- The ItemList Builder/Loader makes coding cleaner, simpler, faster and better maintained.
- The convenient OPC DA V3 Browse and GetProperties methods can be used with the OPC DA V2 servers.
- The UA OPCDA.NET option can be added to the project to allow the application to access the OPC DA and OPC UA servers through the same API.
Access to UA O Servers
OPCDA.NET with the OPCDA.NET-UA option allows clients to access the OPC DA and OPC UA servers through the same API. No external converter is required. DCOM is completely eliminated.
OPC Server Access Controls
OPC Server Access controls are easy to use and handle access to the OPC server efficiently and with extensive error checking. The controls are invisible, doing background work. To add access to the OPC server to a Windows Form or Service application, drag the Visual Studio toolbox controls to the application design panel and configure the properties. The configuration is supported by dialogs. Servers and items can be searched and selected. All access to the OPC server is asynchronous. Application requests are queued and success/error is reported in the completion handler, simplifying the handling of application errors.
DAServer Control
Connects to an OPC server and periodically checks the server connection.
DAGroup Control
Handles Read, Write, and DataChange callbacks for any number of items. Items can be assigned to a control or method to eliminate the application's callback handling. Application encoding is reduced to handle special cases.
Classes QuickUse As
Browse functions display items directly in a TreeView control. Items can be read or written with a single very simple method call using synchronous or asynchronous access. For items accessed asynchronously, the QuickUse class maintains a data buffer and handles data change callbacks. The user can read the current buffer value or request a notification.
DataBinding subscriptions update item values directly in Windows controls and user classes, and user callback handlers are not required.
Navigate Support O
OPCDA.NET offers excellent navigation support, making interactive selection of items simple. With a method call, the server can be navigated to a TreeNode structure in memory or directly in a TreeView control.
- The BrowseShowTree class shows branch offices and items in a single TreeView control.
- The BrowseShowTreeList class shows the branches in a TreeView control and the items of the selected branch in a ListView control. Multiple items can be selected in the ListView control.
Navigating a single branch is also simplified. The convenient OPC DA V3 Browse and GetProperties methods can be used with the OPC DA V3 and V2 servers.
Access to the background server
Each access to the OPC server can take seconds or even minutes due to long DCOM communication wait times or due to long server processing times that can be caused, for example, by slow access to the device.
OPCDA.NET background server access classes handle all server access on background threads and prevent the application from stopping responding during server access. Application quality can be greatly improved without additional development effort. The application also becomes highly robust, all access to the server is checked for a time limit, and the server connection is monitored even without the application having access to the server.
See sample code C# to see how a high-quality OPC DA client application can be short and simple. Visual Studio 2005 code snippets are provided for all methods.
Sample Applications
Many sample applications are provided for C# and VB.NET, complete with Visual Studio 2003 projects. Projects are tested to convert and build with Visual Studio 8 (2005). The samples show how the various features of OPCDA.NET can be used and samples can be used as a starting point for user applications.
Search
Shows how the OPC server can be navigated and items displayed and selected. High-level BrowseTree classes are used.
BrowseV3
Shows how the OPC DA V3 Browse method can be used to browse items in a branch and read all the properties of the item. Only Professional Edition supports these search methods for OPC DA V2 servers.
BrowseLowLevel
Shows how the OPC server can be navigated using browse support functions defined by OPC DA V2. This app can also be used to find any non-conformities in the server navigation interface.
Access to the Background Server
Shows the use of professional edition background server access classes. All access to the server is handled in background threads to ensure that the application never freezes, even with opc access interrupted in a DCOM timout due to a communication failure.
DataBind
Shows how the DataBind class can be used to display values of OPC items in different types of Windows controls without the user having to encode callback handlers.
List items
OPC calls are made with lists of items that are loaded from an XML file. The ItemList XML definition file was created with the ItemListBuilder utility. This feature is only available in OPCDA.NET Professional Edition.
Properties
This client example shows how the OPC server can be navigated and the properties of items queried and read.
Reading
This client uses the RefreshGroup class to read asynchronously the values of two items. The server and item names are encoded in the program.
Update
This sample client uses the OPCDA.NET QuickUse RefreshGroup to periodically update an item through data change callbacks.
Windows Service
This example shows how a Windows service can access OPC servers. The values of three items are transferred to other items on the same server. Multiple OPC servers can be accessed by creating multiple OpcServer objects.
Customer example
Simple-test client applications covering navigation, read, write, and signature capabilities.
Many additional examples of Windows applications can be created with project wizards. Features added to code can be selected in a dialog. With only code for the selected features, the application created is easy to understand and extend to meet user requirements.
Visual Studio New Project Assistant
The project generation wizard generates the sample code for accessing the OPC server according to the user's selections. The generated code is fully functional, easy to understand and an excellent starting point for any OPC client application.
Requirements
Windows 7 (or newer) or Windows Server 2003 (or newer)
.NET 4.x
Visual Studio 2010 or newer with C# or VB.NET
