'Declaration<DataMemberAttribute()> Property PullServerConditionChangedQueueCapacity As Integer
'UsageDim instance As IEasyUAClientConnectionMonitoring Dim value As Integer instance.PullServerConditionChangedQueueCapacity = value value = instance.PullServerConditionChangedQueueCapacity
[DataMember()] int PullServerConditionChangedQueueCapacity {get; set;}
[DataMember()] property int PullServerConditionChangedQueueCapacity { int get(); void set ( int value); }
| Exception | Description |
|---|---|
| System.ArgumentOutOfRangeException | The value of an argument is outside the allowable range of values as defined by the invoked method. This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception. |
Rem This example shows how to monitor connections to and disconnections from the OPC UA server with event pull mechanism. Rem Rem Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . Rem OPC client and subscriber examples in VBScript on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-VBScript . Rem Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own Rem a commercial license in order to use Online Forums, and we reply to every post. Option Explicit ' Instantiate the client object. Dim Client: Set Client = CreateObject("OpcLabs.EasyOpc.UA.EasyUAClient") ' Obtain the client connection monitoring service. Dim ClientConnectionMonitoring: Set ClientConnectionMonitoring = Client.GetServiceByName("OpcLabs.EasyOpc.UA.Services.IEasyUAClientConnectionMonitoring, OpcLabs.EasyOpcUA") If ClientConnectionMonitoring Is Nothing Then WScript.Echo "The client connection monitoring service is not available." WScript.Quit End If ' In order to use event pull, you must set a non-zero queue capacity upfront. ClientConnectionMonitoring.PullServerConditionChangedQueueCapacity = 1000 WScript.Echo "Reading (1)" ' The first read will cause a connection to the server. Dim AttributeData1: Set AttributeData1 = Client.Read("opc.tcp://opcua.demo-this.com:51210/UA/SampleServer", "nsu=http://test.org/UA/Data/ ;i=10853") WScript.Echo AttributeData1 WScript.Echo "Reading (2)" ' The second read, because it closely follows the first one, will reuse the connection that is already open. Dim AttributeData2: Set AttributeData2 = Client.Read("opc.tcp://opcua.demo-this.com:51210/UA/SampleServer", "nsu=http://test.org/UA/Data/ ;i=10853") WScript.Echo AttributeData2 WScript.Echo "Processing server condition changed events for 10 seconds..." ' Because we only started the processing after we have made the reads, there are now events related to opening the ' connection already in the queue, and they will be consumed first. ' Since the connection is now not used for some time, it will be closed. Dim endTime: endTime = Now() + 10*(1/24/60/60) Do Dim EventArgs: Set EventArgs = ClientConnectionMonitoring.PullServerConditionChanged(2*1000) If Not (EventArgs Is Nothing) Then ' Handle the server condition changed event. WScript.Echo EventArgs End If Loop While Now() < endTime WScript.Echo "Finished."