QuickOPC User's Guide and Reference
SubscribeMultipleItems Method (IEasyDAClientExtension)



OpcLabs.EasyOpcClassicCore Assembly > OpcLabs.EasyOpc.DataAccess Namespace > IEasyDAClientExtension Class : SubscribeMultipleItems Method
Subscribe to changes of multiple OPC items.
Overload List
OverloadDescription
Subscribe to changes of multiple OPC items. Subscribe to changes of multiple OPC items. The ItemChanged event will be generated for each significant item change. No callback methods will be invoked.  
Subscribe to changes of multiple OPC items. Subscribe to changes of multiple OPC items with a callback method. The ItemChanged event will be generated for each significant item change, and a specified callback method will be invoked.  
Remarks

 

This method operates (at least in part) asynchronously, with respect to the caller. The actual execution of the operation may be delayed, and the outcome of the operation (if any) is provided to the calling code using an event notification, callback, or other means explained in the text. In a properly written program, this method does not throw any exceptions. You should therefore not put try/catch statements or similar constructs around calls to this method. The only exceptions thrown by this method are for usage errors, i.e. when your code violates the usage contract of the method, such as passing in invalid arguments or calling the method when the state of the object does not allow it. Any operation-related errors (i.e. errors that depend on external conditions that your code cannot reliably check) are indicated by the means the operation returns its outcome (if any), which is described in the text. For more information, see Do not catch any exceptions with asynchronous or multiple-operation methods.
Requirements

Target Platforms: .NET Framework: Windows 10 (selected versions), Windows 11 (selected versions), Windows Server 2016, Windows Server 2022; .NET: Linux, macOS, Microsoft Windows

See Also