Introduction

The Simplex OPC UA Client SDK defines APIs which the ApplicationDeveloper can use to communicate with an OPC UA Server.


Create OPC UA client

Class TOpcUaClient implements the functionalityof the OPC UA client.The record  SpxClientConfig contains the OPC UA client parameters. For client-side callbacks, use theclass inherited from SpxClientCallback.

 An example of how to create OPC UA client:

…

uses SysUtils, Simplex.Client, Simplex.Types;

…

TSimplexClientTest = class(SpxClientCallback)

…

var OpcUaClient: TOpcUaClient;

 ClientConfig: SpxClientConfig;

  SimplexClientTest:TsimplexClientTest;

begin

  try

   ClientConfig.EndpointUrl := 'opc.tcp://localhost:4848';

   ClientConfig.SessionTimeout := 300;

   ClientConfig.TraceLevel := tlWarning;

   ClientConfig.Callback := SimplexClientTest;

   OpcUaClient:= TOpcUaClient.Create(ClientConfig);

 

    if(not OpcUaClient.Connect()) then

   begin

     OpcUaClient.Free();

     Writeln(Format('Error connect to OPC UA server, EndpointUrl=%s',

       [ClientConfig.EndpointUrl]));

     Exit;

    end;

   Writeln(Format('Connect to OPC UA server - OK, EndpointUrl=%s',

     [ClientConfig.EndpointUrl]));

    OpcUaClient.Free();

  except

    onE: Exception do

     Writeln(E.ClassName, ': ', E.Message);

  end;

 

Init session

After connecting, you need to initialize session.

 To initialize session, use:

 function TOpcUaClient.InitSession():SpxBoolean;


Read value

 This Service is used to read one or more Attributes of one or moreNodes. For constructed Attribute values whose elements are indexed, such as anarray, this Service allows Clients to read the entire set of indexed values asa composite, to read individual elements or to read ranges of elements of thecomposite.

 The maxAge parameter is used to direct the Server to access the valuefrom the underlying data source, such as a device, if its copy of the data isolder than that which the maxAge specifies. If the Server cannot meet therequested maximum age, it returns its “best effort” value rather than rejectingthe request.

 To read value, use:

 function TOpcUaClient.ReadValue(AMaxAge:SpxDouble; AtimestampsToReturn:SpxTimestampsToReturn; AReadValueIdList:SpxReadValueIdArray; outAValues: SpxDataValueArray): SpxBoolean;

 

An example of how to read value:

const

 FormatDT = 'yy.mm.dd hh:nn:ss.zzz';

var NodeId: SpxNodeId;

 ReadValues: SpxReadValueIdArray;

 Values: SpxDataValueArray;

…

NodeId.NamespaceIndex := 0;

NodeId.IdentifierType :=SpxIdentifierType_Numeric;

NodeId.IdentifierNumeric := SpxNodeId_Server_ServerStatus_CurrentTime;

SetLength(ReadValues, 1);

ReadValues[0].NodeId := NodeId;

ReadValues[0].AttributeId :=SpxAttributes_Value;

ReadValues[0].IndexRange := '';

ReadValues[0].DataEncoding.NamespaceIndex :=0;

ReadValues[0].DataEncoding.Name := '';

 

if (not OpcUaClient.ReadValue(0,SpxTimestampsToReturn_Both, ReadValues, Values)) then Exit;

if (Length(Values) = 0) then Exit;

Writeln(Format('ReadValue - OK, StatusCode =%u',

 [Ord(Values[0].StatusCode)]));

Writeln(Format('CurrentUtcTime = %s',

 [FormatDateTime(FormatDT, Values[0].Value.AsDateTime)]));

 

Read history

This Service is used to read historicalvalues or Events of one or more Nodes. For constructed Attribute values whoseelements are indexed, such as an array, this Service allows Clients to read theentire set of indexed values as a composite, to read individual elements or toread ranges of elements of the composite. Servers may make historical valuesavailable to Clients using this Service, although the historical valuesthemselves are not visible in the AddressSpace.

The continuationPoint parameter in theHistoryRead is used to mark a point from which to continue the read if not allvalues could be returned in one response. The value is opaque for the Clientand is only used to maintain the state information for the Server to continuefrom.

To read value, use:

 function TOpcUaClient.ReadHistory(AIsReadModified:SpxBoolean; AStartTime, AEndTime:SpxDateTime; AnumValuesPerNode: SpxUInt32;AReturnBounds: SpxBoolean; ATimestampsToReturn: SpxTimestampsToReturn;AReleaseContinuationPoints: SpxBoolean; ANodesToRead:SpxHistoryReadValueIdArray; out AHistoryValues: SpxHistoryReadResultArray):SpxBoolean;

 

An example of how to read history:

var NodeId: SpxNodeId;

 NodesToRead: SpxHistoryReadValueIdArray;

 HistoryValues: SpxHistoryReadResultArray;

  I: integer;

…

NodeId.NamespaceIndex := 1;

NodeId.IdentifierType := SpxIdentifierType_String;

NodeId.IdentifierNumeric :='MyFolder.MyVarStr';

SetLength(NodesToRead, 1);

NodesToRead[0].NodeId := NodeId;

NodesToRead[0].IndexRange := '';

NodesToRead[0].DataEncoding.NamespaceIndex :=0;

NodesToRead[0].DataEncoding.Name := '';

NodesToRead[0].ContinuationPoint := nil;

if (not OpcUaClient.ReadHistory(False,IncHour(Now, -3), Now, 1000,True, SpxTimestampsToReturn_Both, False, NodesToRead, HistoryValues))then Exit;

if (Length(HistoryValues) = 0) then Exit;

Writeln(Format('ReadHistory - OK, StatusCode =%u',

     [Ord(HistoryValues[0].StatusCode)]));

for i := Low(HistoryValues[0].HistoryData) to High(HistoryValues[0].HistoryData) do

     Writeln(Format('HistoryValue[%d]= %s',

         [i,HistoryValues[0].HistoryData[i].Value.AsString]));

 

Write value

This Service is used to write values to oneor more Attributes of one or more Nodes. For constructed Attribute values whoseelements are indexed, such as an array, this Service allows Clients to writethe entire set of indexed values as a composite, to write individual elementsor to write ranges of elements of the composite.

To write value, use:

 function TOpcUaClient.WriteValue(AWriteValueList: SpxWriteValueArray;outAResults: SpxStatusCodeArray):SpxBoolean;

 

An example of how to write value:

var NodeId: SpxNodeId;

 WriteValues: SpxWriteValueArray;

 StatusCodes: SpxStatusCodeArray;

…

NodeId.NamespaceIndex := 1;

NodeId.IdentifierType :=SpxIdentifierType_String;

NodeId.IdentifierNumeric :='MyFolder.MyVarStr';

SetLength(WriteValues, 1);

WriteValues[0].NodeId := NodeId;

WriteValues[0].AttributeId :=SpxAttributes_Value;

WriteValues[0].IndexRange := '';

WriteValues[0].Value.Value.ValueRank :=SpxValueRanks_Scalar;

WriteValues[0].Value.Value.BuiltInType :=SpxType_String;

WriteValues[0].Value.Value.AsString :='value123';

WriteValues[0].Value.StatusCode :=SpxStatusCode_Good;

WriteValues[0].Value.SourceTimestamp := Now;

WriteValues[0].Value.SourcePicoseconds := 0;

WriteValues[0].Value.ServerTimestamp := Now;

WriteValues[0].Value.ServerPicoseconds := 0;

if (not OpcUaClient.WriteValue(WriteValues,StatusCodes)) thenExit;

if (Length(StatusCodes) = 0) then Exit;

Writeln(Format('WriteValue - OK, StatusCode =%u',

     [Ord(StatusCodes[0])]));

 

Call method

Methods represent the function calls ofObjects. TMethods are invoked and return only after completion (successful orunsuccessful). Execution times for methods may vary, depending on the functionthat they perform.

Because Methods may control some aspect ofplant operations, method invocation may depend on environmental or otherconditions. This may be especially true when attempting to re-invoke a method immediatelyafter it has completed execution. Conditions that are required to invoke themethod might not yet have returned to the state that permits the method tostart again.

This Service provides for passing input andoutput arguments to/from a method.

To call method, use:

function TOpcUaClient.CallMethod(AMethodsToCall: SpxCallMethodRequestArray;out Aresults: SpxCallMethodResultArray): SpxBoolean;

 

An example of how to call method:

var NodeId: SpxNodeId;

 MethodsToCall: SpxCallMethodRequestArray;

  MethodResults:SpxCallMethodResultArray;

  i: integer;

…

NodeId.NamespaceIndex := 1;

NodeId.IdentifierType :=SpxIdentifierType_String;

NodeId.IdentifierNumeric :='MyFolder.MyMethod';

SetLength(MethodsToCall, 1);

MethodsToCall[0].MethodId :=  NodeId;

MethodsToCall[0].ObjectId.NamespaceIndex := 1;

MethodsToCall[0].ObjectId.IdentifierType := SpxIdentifierType_Numeric;

MethodsToCall[0].ObjectId.IdentifierNumeric :=0;

SetLength(MethodsToCall[0].InputArguments, 2);

MethodsToCall[0].InputArguments[0].ValueRank:= SpxValueRanks_Scalar;

MethodsToCall[0].InputArguments[0].BuiltInType:= SpxType_String;

MethodsToCall[0].InputArguments[0].AsString :='One';

MethodsToCall[0].InputArguments[1].ValueRank := SpxValueRanks_Scalar;

MethodsToCall[0].InputArguments[1].BuiltInType:= SpxType_String;

MethodsToCall[0].InputArguments[1].AsString :='Two';

if (not OpcUaClient.CallMethod(MethodsToCall,MethodResults)) thenExit;

if (Length(MethodResults) = 0) then Exit;

Writeln(Format('CallMethod - OK, StatusCode =%u',

     [Ord(MethodResults[0].StatusCode)]));

for i := Low(MethodResults[0].OutputArguments)to High(MethodResults[0].OutputArguments)do

     Writeln(Format('MethodOutputArgument[%d]= %s',

         [i,MethodResults[0].OutputArguments[i].AsString]));


Browse

Clients use the Browse Service to navigatethrough the AddressSpace or through a View which is a subset of theAddressSpace.

This Service is used to discover theReferences of a specified Node. The browse can be further limited by the use ofa View. This Browse Service also supports a primitive filtering capability.

To browse, use:

 function TOpcUaClient.Browse(AMaxReferencesPerNode:SpxUInt32; ABrowseDescriptions:SpxBrowseDescriptionArray; outABrowseResultList: SpxBrowseResultArray): SpxBoolean;

 

An example of how to browse:

var BrowseDescriptions: SpxBrowseDescriptionArray;

 BrowseResults: SpxBrowseResultArray;

  i: integer;
…

SetLength(BrowseDescriptions, 1);

BrowseDescriptions[0].NodeId.NamespaceIndex :=0;

BrowseDescriptions[0].NodeId.IdentifierType := SpxIdentifierType_Numeric;

BrowseDescriptions[0].NodeId.IdentifierNumeric:=   SpxNodeId_RootFolder;

BrowseDescriptions[0].BrowseDirection := SpxBrowseDirection_Forward;

BrowseDescriptions[0].ReferenceTypeId.NamespaceIndex:= 0;

BrowseDescriptions[0].ReferenceTypeId.IdentifierType:= SpxIdentifierType_Numeric;

BrowseDescriptions[0].ReferenceTypeId.IdentifierNumeric:= SpxNodeId_HierarchicalReferences;

BrowseDescriptions[0].IncludeSubtypes := True;

BrowseDescriptions[0].NodeClassMask := SpxUInt32(SpxNodeClass_Unspecified);

BrowseDescriptions[0].ResultMask := SpxUInt32(SpxBrowseResultMask_All);

if (not OpcUaClient.Browse(1000,BrowseDescriptions, BrowseResults))then Exit;

if (Length(BrowseResults) = 0) then Exit;

Writeln(Format('Browse - OK, StatusCode = %u',

     [Ord(BrowseResults[0].StatusCode)]));

for i := Low(BrowseResults[0].References) to High(BrowseResults[0].References)do

     Writeln(Format('BrowseDisplayName[%d]= %s',

         [i,BrowseResults[0].References[i].DisplayName.Text]));

 

Browse next

This Service is used to request the next setof Browse or BrowseNext response information that is too large to be sent in asingle response. “Too large” in this context means that the Server is not ableto return a larger response or that the number of results to return exceeds themaximum number of results to return that was specified by the Client in theoriginal Browse request.

To browse next, use:

 function TOpcUaClient.BrowseNext(AReleaseContinuationPoints: SpxBoolean;AContinuationPoints: SpxByteArrayArray; outABrowseResultList: SpxBrowseResultArray): SpxBoolean;

 

An example of how to browse next:

var BrowseDescriptions:SpxBrowseDescriptionArray;

 BrowseResults: SpxBrowseResultArray;

 ContinuationPoints: SpxByteArrayArray;

  i: integer;

…

ContinuationPoints := nil;

SetLength(BrowseDescriptions, 1);

BrowseDescriptions[0].NodeId.NamespaceIndex :=0;

BrowseDescriptions[0].NodeId.IdentifierType := SpxIdentifierType_Numeric;

BrowseDescriptions[0].NodeId.IdentifierNumeric:=   SpxNodeId_RootFolder;

BrowseDescriptions[0].BrowseDirection := SpxBrowseDirection_Forward;

BrowseDescriptions[0].ReferenceTypeId.NamespaceIndex:= 0;

BrowseDescriptions[0].ReferenceTypeId.IdentifierType:= SpxIdentifierType_Numeric;

BrowseDescriptions[0].ReferenceTypeId.IdentifierNumeric:= SpxNodeId_HierarchicalReferences;

BrowseDescriptions[0].IncludeSubtypes := True;

BrowseDescriptions[0].NodeClassMask := SpxUInt32(SpxNodeClass_Unspecified);

BrowseDescriptions[0].ResultMask := SpxUInt32(SpxBrowseResultMask_All);

while True do

begin

  if(Length(ContinuationPoints) = 0) then

  begin

    if(not OpcUaClient.Browse(1000, BrowseDescriptions, BrowseResults))then Exit;

  end

  elsebegin

    if(not OpcUaClient.BrowseNext(False, ContinuationPoints, BrowseResults))then Exit;

  end;

  if(Length(BrowseResults) = 0) then Exit;

 Writeln(Format('Browse - OK, StatusCode = %u',

   [Ord(BrowseResults[0].StatusCode)]));

  for i:= Low(BrowseResults[0].References) to High(BrowseResults[0].References) do

   Writeln(Format('BrowseDisplayName[%d] = %s',

     [i, BrowseResults[0].References[i].DisplayName.Text]));

 

  //continue browse (if more than 1000 references)

  if(Length(BrowseResults[0].ContinuationPoint) > 0) then

  begin

   SetLength(ContinuationPoints, 1);

   ContinuationPoints[0] := BrowseResults[0].ContinuationPoint;

  end

  elseBreak;

end;

 

Createsubscription

This Service is used to create aSubscription. Subscriptions monitor a set of MonitoredItems for Notificationsand return them to the Client in response to Publish requests.

Illegal request values for parameters thatcan be revised do not generate errors. Instead the server will choose defaultvalues and indicate them in the corresponding revised parameter.

To create subscription, use:

 function TOpcUaClient.CreateSubscription(APublishingEnabled: SpxBoolean;ASubscription: SpxSubscription; outASubcriptionId: SpxUInt32; out AsubscriptionResult: SpxSubscriptionResult):SpxBoolean;

 

An example of how to create subscription:

var Subscription: SpxSubscription;

 SubscriptionResult: SpxSubscriptionResult;

 SubcriptionId: SpxUInt32;

…

Subscription.RequestedPublishingInterval :=2000;

Subscription.RequestedLifetimeCount := 200;

Subscription.RequestedMaxKeepAliveCount := 20;

Subscription.MaxNotificationsPerPublish :=20000;

Subscription.Priority := 0;

if (not OpcUaClient.CreateSubscription(True,Subscription, SubcriptionId,SubscriptionResult)) then Exit;

Writeln(Format('CreateSubscription - OK,SubscriptionId = %d, RevisedPublishingInterval=%f, RevisedLifetimeCount=%d, RevisedMaxKeepAliveCount=%d',

     [SubcriptionId,SubscriptionResult.RevisedPublishingInterval, SubscriptionResult.RevisedLifetimeCount, SubscriptionResult.RevisedMaxKeepAliveCount]));

 

Modifysubscription

This Service is used to modify aSubscription.

Illegal request values for parameters thatcan be revised do not generate errors. Instead the server will choose defaultvalues and indicate them in the corresponding revised parameter.

To modify subscription, use:

 function TOpcUaClient.ModifySubscriptiont(ASubcriptionId: SpxUInt32;ASubscription: SpxSubscription; outASubscriptionResult: SpxSubscriptionResult): SpxBoolean;

 

An example of how to modify subscription:

var Subscription: SpxSubscription;

 SubscriptionResult: SpxSubscriptionResult;

 SubcriptionId: SpxUInt32;

…

Subscription.RequestedPublishingInterval :=3000;

Subscription.RequestedLifetimeCount := 300;

Subscription.RequestedMaxKeepAliveCount := 30;

Subscription.MaxNotificationsPerPublish :=30000;

Subscription.Priority := 1;

if (not OpcUaClient.ModifySubscriptiont(SubcriptionId, Subscription,SubscriptionResult)) then Exit;

Writeln(Format('ModifySubscriptiont — OK, RevisedPublishingInterval=%f,RevisedLifetimeCount=%d, RevisedMaxKeepAliveCount=%d',

     [SubscriptionResult.RevisedPublishingInterval, SubscriptionResult.RevisedLifetimeCount, SubscriptionResult.RevisedMaxKeepAliveCount]));

 

Deletesubscription

This Service is invoked to delete one ormore Subscriptions.

Successful completion of this Service causesall MonitoredItems that use the Subscription to be deleted. If this is the lastSubscription assigned to the Client issuing the request, then all Publishrequests queued by that Client are de-queued and a negative response isreturned for each.

To delete subscription, use:

function TOpcUaClient.DeleteSubscriptions(ASubcriptionIds: SpxUInt32Array;out AResults: SpxStatusCodeArray): SpxBoolean;

function TOpcUaClient.DeleteAllSubscriptions:SpxBoolean;

 

An example of how to delete subscription:

var SubcriptionId: SpxUInt32;

 SubcriptionIds: SpxUInt32Array;

 StatusCodes: SpxStatusCodeArray;

…

SetLength(SubcriptionIds, 1);

SubcriptionIds[0] := SubcriptionId;

if (notOpcUaClient.DeleteSubscriptions(SubcriptionIds, StatusCodes))then Exit;

if (Length(StatusCodes) = 0) then Exit;

Writeln(Format('DeleteSubscriptions- OK,StatusCode = %u',

     [Ord(StatusCodes[0])]));

 

Createmonitored items

This Service is used to create and add one or more MonitoredItems to aSubscription. A MonitoredItem is deleted automatically by the Server when theSubscription is deleted. Deleting a MonitoredItem causes its entire set oftriggered item links to be deleted, but has no effect on the MonitoredItemsreferenced by the triggered items.

Illegal request values for parameters that can be revised do notgenerate errors. Instead the server will choose default values and indicatethem in the corresponding revised parameter.

To create monitored items, use:

 function TOpcUaClient.CreateMonitoredItems(ASubcriptionId: SpxUInt32; AMonitoredItems:SpxMonitoredItemArray; out AMonitoredItemResult:SpxMonitoredItemResultArray): SpxBoolean; overload;

function TOpcUaClient.CreateMonitoredItems(ASubcriptionId: SpxUInt32;ATimestampsToReturn: SpxTimestampsToReturn; AMonitoredItems:SpxMonitoredItemArray; out AMonitoredItemResult:SpxMonitoredItemResultArray): SpxBoolean; overload;

function TOpcUaClient.CreateMonitoredItems(ASubcriptionId: SpxUInt32;ATimestampsToReturn: SpxTimestampsToReturn; AFilter: SpxDataChangeFilter;AmonitoredItems: SpxMonitoredItemArray; outAmonitoredItemResult: SpxMonitoredItemResultArray):SpxBoolean; overload;

function TOpcUaClient.CreateMonitoredItems(ASubcriptionId: SpxUInt32;ATimestampsToReturn: SpxTimestampsToReturn; AFilter: SpxAggregateFilter;AmonitoredItems: SpxMonitoredItemArray; outAMonitoredItemResult: SpxMonitoredItemResultArray):SpxBoolean; overload;

function TopcUaClient.CreateMonitoredItems(ASubcriptionId: SpxUInt32;ATimestampsToReturn: SpxTimestampsToReturn; AFilter: SpxFilterParams;AmonitoredItems: SpxMonitoredItemArray; outAmonitoredItemResult: SpxMonitoredItemResultArray): SpxBoolean; overload;

 

An example of how to create monitored items:

const VariableClientHandle = 1;

var NodeId: SpxNodeId;

 SubcriptionId: SpxUInt32;

 MonitoredItems: SpxMonitoredItemArray;

  MonitoredItemResult:SpxMonitoredItemResultArray;

…

NodeId.NamespaceIndex := 0;

NodeId.IdentifierType :=SpxIdentifierType_Numeric;

NodeId.IdentifierNumeric := SpxNodeId_Server_ServerStatus_CurrentTime;

SetLength(MonitoredItems, 1);

MonitoredItems[0].NodeId := NodeId;

MonitoredItems[0].AttributeId :=SpxAttributes_Value;

MonitoredItems[0].IndexRange := '';

MonitoredItems[0].DataEncoding.NamespaceIndex:= 0;

MonitoredItems[0].DataEncoding.Name := '';

MonitoredItems[0].MonitoringMode :=SpxMonitoringMode_Reporting;

MonitoredItems[0].ClientHandle :=VariableClientHandle;

MonitoredItems[0].SamplingInterval := 500;

MonitoredItems[0].QueueSize := 1000;

MonitoredItems[0].DiscardOldest := True;

if (notOpcUaClient.CreateMonitoredItems(SubcriptionId, SpxTimestampsToReturn_Both,MonitoredItems, MonitoredItemResult))then Exit;

if (Length(MonitoredItemResult) = 0) thenExit;

Writeln(Format('CreateMonitoredItems - OK,StatusCode=%u, MonitoredItemId=%d,SamplingInterval=%f, QueueSize=%d',

     [MonitoredItemResult[0].StatusCode, MonitoredItemResult[0].MonitoredItemId, MonitoredItemResult[0].SamplingInterval, MonitoredItemResult[0].QueueSize]));

 

Modifymonitored items

This Service is used to modify MonitoredItems of a Subscription. Changesto the sampling interval and filter take effect at the beginning of the nextsampling interval (the next time the sampling timer expires).

Illegal request values for parameters that can be revised do notgenerate errors. Instead the server will choose default values and indicatethem in the corresponding revised parameter.

To modify monitored items, use:

 function TOpcUaClient.ModifyMonitoredItems(ASubcriptionId: SpxUInt32;AMonitoredItems: SpxModifyMonitoredItemArray; outAMonitoredItemResult: SpxModifyMonitoredItemResultArray):SpxBoolean; overload;

function TOpcUaClient.ModifyMonitoredItems(ASubcriptionId: SpxUInt32;ATimestampsToReturn: SpxTimestampsToReturn; AMonitoredItems:SpxModifyMonitoredItemArray; outAMonitoredItemResult: SpxModifyMonitoredItemResultArray):SpxBoolean; overload;

function TOpcUaClient.ModifyMonitoredItems(ASubcriptionId: SpxUInt32;ATimestampsToReturn: SpxTimestampsToReturn; AFilter:SpxDataChangeFilter; AMonitoredItems: SpxModifyMonitoredItemArray;out AmonitoredItemResult: SpxModifyMonitoredItemResultArray):SpxBoolean; overload;

function TOpcUaClient.ModifyMonitoredItems(ASubcriptionId: SpxUInt32;ATimestampsToReturn: SpxTimestampsToReturn; AFilter:SpxAggregateFilter; AMonitoredItems: SpxModifyMonitoredItemArray;out AmonitoredItemResult: SpxModifyMonitoredItemResultArray):SpxBoolean; overload;

function TOpcUaClient.ModifyMonitoredItems(ASubcriptionId: SpxUInt32;ATimestampsToReturn: SpxTimestampsToReturn; AFilter:SpxFilterParams; AMonitoredItems: SpxModifyMonitoredItemArray;out AmonitoredItemResult: SpxModifyMonitoredItemResultArray):SpxBoolean; overload;

 

An example of how to modify monitored items:

const VariableClientHandle = 1;

var NodeId: SpxNodeId;

 SubcriptionId: SpxUInt32;

 MonitoredItems: SpxMonitoredItemArray;

 MonitoredItemResult: SpxMonitoredItemResultArray;

…

SetLength(ModifyItems, 1);

ModifyItems[0].MonitoredItemId := MonitoredItemId;

ModifyItems[0].ClientHandle := VariableClientHandle;

ModifyItems[0].SamplingInterval := 600;

ModifyItems[0].DiscardOldest := True;

if (not OpcUaClient.ModifyMonitoredItems(SubcriptionId, SpxTimestampsToReturn_Both,ModifyItems, ModifyItemResult)) then Exit;

if (Length(ModifyItemResult) = 0) then Exit;

Writeln(Format('ModifyMonitoredItems - OK, StatusCode=%u, SamplingInterval=%f,QueueSize=%d',

     [ModifyItemResult[0].StatusCode, ModifyItemResult[0].SamplingInterval, ModifyItemResult[0].QueueSize]));

 

Setmonitoring mode

This Service is used to set the monitoringmode for one or more MonitoredItems of a Subscription. Setting the mode to Disabled causesall queued Notifications to be deleted.

To set monitoring mode, use:

function TOpcUaClient.SetMonitoringMode(ASubcriptionId:SpxUInt32; AMonitoringMode:SpxMonitoringMode; AMonitoredItemIds: SpxUInt32Array;out AResults: SpxStatusCodeArray): SpxBoolean;

 

An example of how to set monitoring mode:

var SubcriptionId, MonitoredItemId: SpxUInt32;

 MonitoredItemIds: SpxUInt32Array;

 StatusCodes: SpxStatusCodeArray;

…

SetLength(MonitoredItemIds, 1);

MonitoredItemIds[0] := MonitoredItemId;

if (not OpcUaClient.SetMonitoringMode(SubcriptionId, SpxMonitoringMode_Reporting,MonitoredItemIds, StatusCodes)) thenExit;

if (Length(StatusCodes) = 0) then Exit;

Writeln(Format('SetMonitoringMode - OK,StatusCode=%u',

     [StatusCodes[0]]));

 

Delete monitoreditems

This Service is used to remove one or more MonitoredItems of aSubscription. When a MonitoredItem is deleted, its triggered item links arealso deleted.

To delete monitored items, use:

function TopcUaClient.DeleteMonitoredItems(ASubcriptionId: SpxUInt32;AMonitoredItemIds: SpxUInt32Array; outAResults: SpxStatusCodeArray): SpxBoolean;

 

An example of how to delete monitored items:

var SubcriptionId: SpxUInt32;

 MonitoredItemIds: SpxUInt32Array;

 StatusCodes: SpxStatusCodeArray;

…

if (not OpcUaClient.DeleteMonitoredItems(SubcriptionId, MonitoredItemIds,StatusCodes)) then Exit;

if (Length(StatusCodes) = 0) then Exit;

Writeln(Format('DeleteMonitoredItems - OK, StatusCode=%u',

     [StatusCodes[0]]));