Common Fundamentals > Identifying Information in OPC UA Client-Server > OPC UA Index Range Lists |
OPC Unified Architecture has support for single- and multidimensional arrays in data values. In addition, it is also possible to work with (read, write, subscribe to) only a subset of an array, so that the whole (potentially large) array does not have to be transferred between the OPC server and OPC client.
OPC Studio uses Index Range Lists (UAIndexRangeList objects) to control which parts of array value should be accessed. An index range list can be used to identify the whole array, a single element of a structure or an array, or a single range of indexes for arrays. Index Range List is basically a list of individual Index Ranges (UAIndexRange objects), each containing a range for a single dimension of an array.
There is an implicit conversion from an integer (Int32) to a UAIndexRange, so if your language (such as C#) supports implicit conversions, an index range containing just a single element can be written simply as the element index, without explicitly constructing the UAIndexRange object.
Besides constructing the UAIndexRangeList from individual UAIndexRange objects, it is also possible to specify the index range list by parsing a string, using static UAIndexRangeList.TryParse method.
Examples of index range strings:
Dimensions are separated by commas. A minimum and maximum value, separated by a colon, denotes a range of index. If the colon is missing, only a single for an index is selected. An empty string denotes the whole array.
One-dimensional index range lists can be easily constructed using the UAIndexRangeList.OneDimension static method, passing it either the single index, or minimum and maximum indices.
UAIndexRangeList can be given as IndexRangeList property of the UAAttributeArguments object (and derived objects, such as UAReadArguments, UAWriteArguments, UAWriteValueArguments, and EasyUAMonitoredItemArguments). You can then pass this object to a corresponding method on the main EasyUAClient object.
// This example shows how to read a range of values from an array. // // Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . using System; using OpcLabs.EasyOpc.UA; using OpcLabs.EasyOpc.UA.OperationModel; namespace UADocExamples._UAIndexRangeList { partial class Usage { public static void ReadValue() { UAEndpointDescriptor endpointDescriptor = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"; // or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported) // or "https://opcua.demo-this.com:51212/UA/SampleServer/" // Instantiate the client object var client = new EasyUAClient(); // Obtain the value, indicating that just the elements 2 to 4 should be returned object value; try { value = client.ReadValue( new UAReadArguments( endpointDescriptor, "nsu=http://test.org/UA/Data/ ;ns=2;i=10305", // /Data.Static.Array.Int32Value UAIndexRangeList.OneDimension(2, 4))); } catch (UAException uaException) { Console.WriteLine("*** Failure: {0}", uaException.GetBaseException().Message); return; } // Cast to typed array var arrayValue = (Int32[]) value; // Display results for (int i = 0; i < 3; i++) Console.WriteLine("arrayValue[{0}]: {1}", i, arrayValue[i]); // Example output: //arrayValue[0]: 180410224 //arrayValue[1]: 1919239969 //arrayValue[2]: 1700185172 } } }
# This example shows how to read a range of values from an array. # # Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . # OPC client and subscriber examples in Python on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-Python . # The QuickOPC package is needed. Install it using "pip install opclabs_quickopc". import opclabs_quickopc # Import .NET namespaces. from OpcLabs.EasyOpc.UA import * from OpcLabs.EasyOpc.UA.OperationModel import * endpointDescriptor = UAEndpointDescriptor('opc.tcp://opcua.demo-this.com:51210/UA/SampleServer') # or 'http://opcua.demo-this.com:51211/UA/SampleServer' (currently not supported) # or 'https://opcua.demo-this.com:51212/UA/SampleServer/' # Instantiate the client object. client = EasyUAClient() # Obtain the value, indicating that just the elements 2 to 4 should be returned try: arrayValue = IEasyUAClientExtension.ReadValue(client, endpointDescriptor, UANodeDescriptor('nsu=http://test.org/UA/Data/ ;ns=2;i=10305'), # /Data.Static.Array.Int32Value UAIndexRangeList.OneDimension(2, 4)) except UAException as uaException: print('*** Failure: ' + uaException.GetBaseException().Message) exit() # Display results. for i, elementValue in enumerate(arrayValue): print('arrayValue[', i, ']: ', elementValue, sep='') print() print('Finished.')
' This example shows how to read a range of values from an array. ' ' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . Imports OpcLabs.EasyOpc.UA Imports OpcLabs.EasyOpc.UA.OperationModel Namespace _UAIndexRangeList Friend Class Usage Public Shared Sub ReadValue() Dim endpointDescriptor As UAEndpointDescriptor = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer" ' or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported) ' or "https://opcua.demo-this.com:51212/UA/SampleServer/" ' Instantiate the client object Dim client = New EasyUAClient() ' Obtain the value, indicating that just the elements 2 to 4 should be returned Dim value As Object Try value = client.ReadValue( _ New UAReadArguments( _ endpointDescriptor, _ "nsu=http://test.org/UA/Data/ ;i=10305", _ UAIndexRangeList.OneDimension(2, 4))) ' or "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer" Catch uaException As UAException Console.WriteLine("*** Failure: {0}", uaException.GetBaseException.Message) Exit Sub End Try ' Cast to typed array Dim arrayValue = DirectCast(value, Int32()) ' Display results For i = 0 To 2 Console.WriteLine("arrayValue[{0}]: {1}", i, arrayValue(i)) Next End Sub End Class End Namespace
// This example shows how to read a range of values from an array. // // Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . class procedure Usage.ReadValue; var Client: _EasyUAClient; EndpointDescriptor: string; ReadArguments1: _UAReadArguments; Arguments, Results: OleVariant; I: Cardinal; IndexRange: _UAIndexRange; IndexRangeList: OpcLabs_EasyOpcUA_TLB._UAIndexRangeList; ArrayValue: OleVariant; Value: Integer; ValueResult: _ValueResult; begin EndpointDescriptor := //'http://opcua.demo-this.com:51211/UA/SampleServer'; //'https://opcua.demo-this.com:51212/UA/SampleServer/'; 'opc.tcp://opcua.demo-this.com:51210/UA/SampleServer'; // Instantiate the client object Client := CoEasyUAClient.Create; // Prepare the arguments, indicating that just the elements 2 to 4 should be returned. IndexRangeList := CoUAIndexRangeList.Create; IndexRange := CoUAIndexRange.Create; IndexRange.Minimum := 2; IndexRange.Maximum := 4; IndexRangeList.Add(IndexRange); ReadArguments1 := CoUAReadArguments.Create; ReadArguments1.EndpointDescriptor.UrlString := EndpointDescriptor; ReadArguments1.NodeDescriptor.NodeId.ExpandedText := 'nsu=http://test.org/UA/Data/ ;ns=2;i=10305'; ReadArguments1.IndexRangeList := IndexRangeList; Arguments := VarArrayCreate([0, 0], varVariant); Arguments[0] := ReadArguments1; // Obtain value. TVarData(Results).VType := varArray or varVariant; TVarData(Results).VArray := PVarArray(Client.ReadMultipleValues(Arguments)); ValueResult := IInterface(Results[0]) as _ValueResult; if not ValueResult.Succeeded then begin WriteLn(' *** Failure: ', ValueResult.Exception.GetBaseException.Message); Exit; end; // Display results ArrayValue := ValueResult.Value; for I := VarArrayLowBound(ArrayValue, 1) to VarArrayHighBound(ArrayValue, 1) do begin Value := ArrayValue[I]; WriteLn('arrayValue[', I, ']: ', Value); end; VarClear(Results); VarClear(Arguments); // Example output: //arrayValue[0]: 180410224 //arrayValue[1]: 1919239969 //arrayValue[2]: 1700185172 end;
// This example shows how to read a range of values from an array. // // Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . $EndpointDescriptor = //"http://opcua.demo-this.com:51211/UA/SampleServer"; //"https://opcua.demo-this.com:51212/UA/SampleServer/"; "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"; // Instantiate the client object $Client = new COM("OpcLabs.EasyOpc.UA.EasyUAClient"); // Prepare the arguments, indicating that just the elements 2 to 4 should be returned. $IndexRangeList = new COM("OpcLabs.EasyOpc.UA.UAIndexRangeList"); $IndexRange = new COM("OpcLabs.EasyOpc.UA.UAIndexRange"); $IndexRange->Minimum = 2; $IndexRange->Maximum = 4; $IndexRangeList->Add($IndexRange); $ReadArguments1 = new COM("OpcLabs.EasyOpc.UA.OperationModel.UAReadArguments"); $ReadArguments1->EndpointDescriptor->UrlString = $EndpointDescriptor; $ReadArguments1->NodeDescriptor->NodeId->ExpandedText = "nsu=http://test.org/UA/Data/ ;ns=2;i=10305"; $ReadArguments1->IndexRangeList = $IndexRangeList; $arguments[0] = $ReadArguments1; // Obtain value. $results = $Client->ReadMultipleValues($arguments); $ValueResult = $results[0]; if (!$ValueResult->Succeeded) { printf("*** Failure: %s\n", $ValueResult->ErrorMessageBrief); Exit(); } // Display results $ArrayValue = $ValueResult->Value; for ($i = 0; $i <= 2; $i++) { printf("arrayValue[d]s\n", $i, $ArrayValue[$i]); } // Example output: //arrayValue[0]: 180410224 //arrayValue[1]: 1919239969 //arrayValue[2]: 1700185172
REM This example shows how to read a range of values from an array. REM REM Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . Private Sub Usage_ReadValue_Command_Click() OutputText = "" Dim endpointDescriptor As String 'endpointDescriptor = "http://opcua.demo-this.com:51211/UA/SampleServer" 'endpointDescriptor = "https://opcua.demo-this.com:51212/UA/SampleServer/" endpointDescriptor = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer" ' Instantiate the client object Dim Client As New EasyUAClient ' Prepare the arguments, indicating that just the elements 2 to 4 should be returned. Dim indexRangeList As New UAIndexRangeList Dim indexRange As New UAIndexRange indexRange.Minimum = 2 indexRange.Maximum = 4 indexRangeList.Add indexRange Dim readArguments1 As New UAReadArguments readArguments1.endpointDescriptor.UrlString = endpointDescriptor readArguments1.NodeDescriptor.NodeId.expandedText = "nsu=http://test.org/UA/Data/ ;ns=2;i=10305" Set readArguments1.indexRangeList = indexRangeList Dim arguments(0) As Variant Set arguments(0) = readArguments1 ' Obtain value. Dim results() As Variant results = Client.ReadMultipleValues(arguments) Dim valueResult As valueResult Set valueResult = results(0) If Not valueResult.Succeeded Then OutputText = OutputText & "*** Failure: " & valueResult.Exception.GetBaseException.Message & vbCrLf Exit Sub End If ' Display results Dim arrayValue() As Long arrayValue = valueResult.value Dim i: For i = LBound(arrayValue) To UBound(arrayValue) OutputText = OutputText & "arrayValue(" & i & "):" & arrayValue(i) & vbCrLf Next ' Example output: 'arrayValue(0): 180410224 'arrayValue(1): 1919239969 'arrayValue(2): 1700185172 End Sub
Rem This example shows how to read a range of values from an array. Rem Rem Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . Option Explicit Dim endpointDescriptor: endpointDescriptor = _ "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer" '"http://opcua.demo-this.com:51211/UA/SampleServer" '"https://opcua.demo-this.com:51212/UA/SampleServer/" ' Instantiate the client object Dim Client: Set Client = CreateObject("OpcLabs.EasyOpc.UA.EasyUAClient") ' Prepare the arguments, indicating that just the elements 2 to 4 should be returned. Dim IndexRangeList: Set IndexRangeList = CreateObject("OpcLabs.EasyOpc.UA.UAIndexRangeList") Dim IndexRange: Set IndexRange = CreateObject("OpcLabs.EasyOpc.UA.UAIndexRange") IndexRange.Minimum = 2 IndexRange.Maximum = 4 IndexRangeList.Add IndexRange ' Dim ReadArguments1: Set ReadArguments1 = CreateObject("OpcLabs.EasyOpc.UA.OperationModel.UAReadArguments") ReadArguments1.EndpointDescriptor.UrlString = endpointDescriptor ReadArguments1.NodeDescriptor.NodeId.ExpandedText = "nsu=http://test.org/UA/Data/ ;ns=2;i=10305" ReadArguments1.IndexRangeList = IndexRangeList Dim arguments(0) Set arguments(0) = ReadArguments1 ' Obtain the value. Dim results: results = Client.ReadMultipleValues(arguments) Dim ValueResult: Set ValueResult = results(0) If Not ValueResult.Succeeded Then WScript.Echo "*** Failure: " & ValueResult.Exception.GetBaseException().Message WScript.Quit End If ' VBScript can only handle well arrays of VARIANTs; most other COM tool will be able to use simply the .Value property. Dim arrayValue: arrayValue = ValueResult.RegularizedValue ' Display results Dim i: For i = 0 To 2 WScript.Echo "arrayValue[" & i & "]: " & arrayValue(i) Next ' Example output: 'arrayValue[0]: 180410224 'arrayValue[1]: 1919239969 'arrayValue[2]: 1700185172
// This example shows how to subscribe to range of values from an array. // // Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . using System; using OpcLabs.EasyOpc.UA; using OpcLabs.EasyOpc.UA.OperationModel; namespace UADocExamples._UAIndexRangeList { partial class Usage { public static void Subscribe() { UAEndpointDescriptor endpointDescriptor = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"; // or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported) // or "https://opcua.demo-this.com:51212/UA/SampleServer/" // Instantiate the client object var client = new EasyUAClient(); Console.WriteLine("Subscribing to range..."); var attributeArguments = new UAAttributeArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10933") { IndexRangeList = UAIndexRangeList.OneDimension(2, 4) }; var monitoredItemArguments = new UAMonitoredItemArguments(attributeArguments, monitoringParameters:1000); // The callback is a lambda expression the displays the value client.SubscribeMonitoredItem(monitoredItemArguments, (sender, eventArgs) => { if (eventArgs.Succeeded) { var arrayValue = eventArgs.AttributeData.Value as Int32[]; if (!(arrayValue is null)) Console.WriteLine($"Value: {{{String.Join(",", arrayValue)}}}"); } else Console.WriteLine($"*** Failure: {eventArgs.ErrorMessageBrief}"); }); Console.WriteLine("Processing data change events for 10 seconds..."); System.Threading.Thread.Sleep(10 * 1000); Console.WriteLine("Unsubscribing..."); client.UnsubscribeAllMonitoredItems(); Console.WriteLine("Waiting for 2 seconds..."); System.Threading.Thread.Sleep(2 * 1000); } } }
# This example shows how to subscribe to range of values from an array. # # Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . # OPC client and subscriber examples in Python on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-Python . # The QuickOPC package is needed. Install it using "pip install opclabs_quickopc". import opclabs_quickopc import time # Import .NET namespaces. from OpcLabs.EasyOpc.UA import * from OpcLabs.EasyOpc.UA.OperationModel import * def dataChangeNotification(sender, eventArgs): # Display value. if eventArgs.Succeeded: arrayValue = eventArgs.AttributeData.Value print('Value: {', ", ".join(["{}"]*len(arrayValue)).format(*arrayValue), '}', sep='') else: print('*** Failure: ', eventArgs.ErrorMessageBrief, sep='') endpointDescriptor = UAEndpointDescriptor('opc.tcp://opcua.demo-this.com:51210/UA/SampleServer') # or 'http://opcua.demo-this.com:51211/UA/SampleServer' (currently not supported) # or 'https://opcua.demo-this.com:51212/UA/SampleServer/' # Instantiate the client object. client = EasyUAClient() print('Subscribing to range...') attributeArguments = UAAttributeArguments(endpointDescriptor, UANodeDescriptor('nsu=http://test.org/UA/Data/ ;i=10933')) attributeArguments.IndexRangeList = UAIndexRangeList.OneDimension(2, 4) monitoredItemArguments = UAMonitoredItemArguments(attributeArguments, UAMonitoringParameters(1000)) IEasyUAClientExtension.SubscribeMonitoredItem(client, monitoredItemArguments, EasyUADataChangeNotificationEventHandler(dataChangeNotification)) print('Processing data change events for 10 seconds...') time.sleep(10) print('Unsubscribing...') client.UnsubscribeAllMonitoredItems() print('Waiting for 2 seconds...') time.sleep(2) print('Finished.')
' This example shows how to subscribe to range of values from an array. ' ' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . Imports Opc.Ua Imports OpcLabs.EasyOpc.UA Imports OpcLabs.EasyOpc.UA.OperationModel Namespace _UAIndexRangeList Partial Friend Class Usage Public Shared Sub Subscribe() ' Define which server we will work with. Dim endpointDescriptor As UAEndpointDescriptor = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer" ' or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported) ' or "https://opcua.demo-this.com:51212/UA/SampleServer/" ' Instantiate the client object Dim client = New EasyUAClient() Console.WriteLine("Subscribing to range...") Dim attributeArguments = New UAAttributeArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10933") With { .IndexRangeList = UAIndexRangeList.OneDimension(2, 4) } Dim monitoredItemArguments = New UAMonitoredItemArguments(attributeArguments, monitoringParameters:=1000) ' The callback is a lambda expression the displays the value client.SubscribeMonitoredItem(monitoredItemArguments, Sub(sender, eventArgs) If eventArgs.Succeeded Then Dim arrayValue = CType(eventArgs.AttributeData.Value, Int32()) If (arrayValue IsNot Nothing) Then Console.WriteLine($"Value: {{{String.Join(",", arrayValue)}}}") End If Else Console.WriteLine("*** Failure: {0}", eventArgs.ErrorMessageBrief) End If End Sub) Console.WriteLine("Processing data change events for 10 seconds...") Threading.Thread.Sleep(10 * 1000) Console.WriteLine("Unsubscribing...") client.UnsubscribeAllMonitoredItems() Console.WriteLine("Waiting for 2 seconds...") Threading.Thread.Sleep(2 * 1000) End Sub End Class End Namespace
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