OPC Studio User's Guide and Reference
EasyDAClientCore Class Members
Fields  Properties  Methods  Events


OpcLabs.EasyOpcClassic Assembly > OpcLabs.EasyOpc.DataAccess Namespace : EasyDAClientCore Class

The following tables list the members exposed by EasyDAClientCore.

Public Constructors
 NameDescription
Public ConstructorEasyDAClientCore ConstructorOverloaded.   
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Public Fields
 NameDescription
Public FieldDefaultIsolatedDefault value of the Isolated property. Equals to false.  
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Public Properties
 NameDescription
Public Propertystatic (Shared in Visual Basic)AdaptableParametersAdaptable parameters for non-isolated client objects.  
Public PropertyAliasProviderThe alias provider to be used for resolving aliases by this component.  
Public PropertyContainer (Inherited from System.ComponentModel.Component)
Public PropertyCustomReferenceCan be used to distinguish otherwise equal widgets. (Inherited from OpcLabs.BaseLib.Widgets.Widget)
Public PropertyInstanceParametersContains parameters that influence the behavior of just this instance of the component.  
Public PropertyIsolatedSpecifies that you wish that the EasyDAClientCore object instance works with an "isolated" connection to the OPC server, i.e. one that is not shared with other instances.  
Public PropertyIsolatedParametersContains parameters that influence the behavior of the component when it is isolated.  
Public PropertyLicenseInfoProvides dictionary of license data fields and their values.  
Public PropertyNotificationQueueCapacityCapacity of the notification queue. (Inherited from OpcLabs.BaseLib.Widgets.NotifyingWidget)
Public PropertyNotificationQueueIdleTimeToSleepThe idle time before the internal thread executing the queued notifications is stopped (in milliseconds). (Inherited from OpcLabs.BaseLib.Widgets.NotifyingWidget)
Public PropertyPullItemChangedQueueCapacityCapacity of the event pull queue for item changes.  
Public PropertyQueueNotificationsDetermines whether the component will deliver all notifications in a queued manner. (Inherited from OpcLabs.BaseLib.Widgets.NotifyingWidget)
Public Propertystatic (Shared in Visual Basic)ServiceProviderEndpointDescriptorProvider endpoint descriptor.  
Public Propertystatic (Shared in Visual Basic)SharedParametersParameters that are always shared by all instances of the component.  
Public Propertystatic (Shared in Visual Basic)SharedServiceContainerContainer for services that are shared by all instances of the component.  
Public Propertystatic (Shared in Visual Basic)SharedServiceProviderProvides services that are shared by all instances of the component.  
Public PropertySite (Inherited from System.ComponentModel.Component)
Public PropertySupportedTechnologiesGets the OPC technologies supported.  
Public PropertySynchronizationContextContains synchronization context used by the object when performing asynchronous operations (including event notifications). (Inherited from OpcLabs.BaseLib.Widgets.NotifyingWidget)
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Protected Properties
 NameDescription
Protected PropertyCanRaiseEvents (Inherited from System.ComponentModel.Component)
Protected PropertyDesignMode (Inherited from System.ComponentModel.Component)
Protected PropertyEvents (Inherited from System.ComponentModel.Component)
Protected PropertyServiceContainerThe service container provided by this widget to inheritors. (Inherited from OpcLabs.BaseLib.Widgets.Widget)
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Public Methods
 NameDescription
Public MethodBrowseAccessPathsBrowses the possible access paths of a specified OPC item. Specify server descriptor, and node descriptor.  
Public MethodBrowseNodesBrowses the specified branch (or root) in OPC server's address space, and returns information about child nodes (both branches and leaves) found. Specify server descriptor, parent item ID, and node filter.  
Public MethodBrowsePropertiesBrowse for available item properties of a specified OPC item. Specify server descriptor, and node descriptor.  
Public MethodBrowseServersBrowses the specified computer and returns information about OPC (Data Access) servers found.  
Public MethodChangeMultipleItemSubscriptionsChanges parameters of subscriptions to multiple OPC items.  
Public MethodCloneOverridden.   
Public MethodCreateObjRefCreates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object. (Inherited from System.MarshalByRefObject)
Public MethodDisposeOverloaded. Overridden. Clean up any resources being used.  
Public MethodEquals (Inherited from object)
Public MethodGetHashCodeServes as the default hash function. (Inherited from object)
Public MethodGetItemSubscriptionArgumentsObtains parameters of specified item subscription.  
Public MethodGetLifetimeServiceRetrieves the current lifetime service object that controls the lifetime policy for this instance. (Inherited from System.MarshalByRefObject)
Public MethodGetMultiplePropertyValuesGets values of multiple OPC properties, specifying an array of property arguments objects.  
Public MethodGetObjectDataOverridden.   
Public MethodGetSchema (Inherited from OpcLabs.BaseLib.Widgets.Widget)
Public MethodGetServiceOverridden.   
Public MethodGetTypeGets the System.Type of the current instance. (Inherited from object)
Public MethodInitializeLifetimeServiceObtains a lifetime service object to control the lifetime policy for this instance. (Inherited from System.MarshalByRefObject)
Public MethodPullMultipleItemChangesAttempts to pull multiple OPC item changes subscribed to by the IEasyDAClient.SubscribeMultipleItems or SubscribeItem method.  
Public MethodReadMultipleItemsReads multiple named items from an OPC server or OPC servers, using array of argument objects as an input. Values, qualities and timestamps are returned.  
Public MethodReadXml (Inherited from OpcLabs.BaseLib.Widgets.Widget)
Public MethodResetSets the object properties back to their defaults.  
Public MethodSubscribeMultipleItemsSubscribe to changes of multiple OPC items. The IEasyDAClient.ItemChanged event will be generated for each significant item change. Callback methods will be invoked if they are specified in the argument objects.  
Public MethodToStringOverridden.   
Public MethodUnsubscribeAllItemsUnsubscribe from changes of all OPC items.  
Public MethodUnsubscribeMultipleItemsUnsubscribe from changes of multiple OPC items, specifying an "enumerable" of integer handles.  
Public MethodValueEqualsOverloaded. Determines whether the specified EasyDAClientCore is value equal to the current object.  
Public MethodWriteMultipleItemsWrites named items into an OPC server or OPC servers. Values, qualities and timestamps are written.  
Public MethodWriteMultipleItemValuesWrites values into named items in an OPC server or OPC servers. Only the item values are written (qualities and timestamp are not written).  
Public MethodWriteXml (Inherited from OpcLabs.BaseLib.Widgets.Widget)
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Protected Methods
 NameDescription
Protected MethodCallbackErrorOverridden. Processes an error that has occurred during a callback.  
Protected MethodFinalize (Inherited from System.ComponentModel.Component)
Protected MethodMemberwiseCloneOverloaded. Creates a shallow copy of the current System.MarshalByRefObject object. (Inherited from System.MarshalByRefObject)
Protected MethodOnContextTypesChangedInfrastructure. (Inherited from OpcLabs.BaseLib.Widgets.Widget)
Protected MethodOnNotificationEnqueuerOverflowOverridden. Infrastructure.  
Protected MethodOnNotificationEnqueuerOverflowClearingOverridden. Infrastructure.  
Protected MethodReadXmlElementOverridden. Infrastructure.  
Protected MethodSendCallbackErrorOverridden. Processes an error that has occurred during a callback.  
Protected MethodSynchronizeOverloaded. Invokes the specified action in a synchronized manner. (Inherited from OpcLabs.BaseLib.Widgets.NotifyingWidget)
Protected MethodWriteXmlElementOverridden. Infrastructure.  
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Extension Methods
 NameDescription
Public Extension MethodBrowseAccessPaths

Browses the possible access paths of a specified OPC item.

Browse for access paths. Specify machine name, server class, and item ID.

Public Extension MethodBrowseBranchesOverloaded. Browses the specified branch (or root) in OPC server's address space, and returns information about child branches found.

The BrowseBranches methods return the branches available under the specified parent branch in the OPC-DA address space.

The server(s) can be local or can be remotely accessed via DCOM.

Public Extension MethodBrowseLeavesOverloaded. Browses the specified branch (or root) in OPC server's address space, and returns information about child leaves found.

The BrowseLeaves methods return the leaves available under the specified parent branch in the OPC-DA address space.

The server(s) can be local or can be remotely accessed via DCOM.

Public Extension MethodBrowseNodes

Browses the specified branch (or root) in OPC server's address space, and returns information about child nodes (both branches and leaves) found.

Browse for child nodes. Specify machine name, server class, parent item ID, and node filter.

Public Extension MethodBrowseOne

Browses the nodes in OPC DA server's address space. Starts from the specified node, and returns information about child nodes found.

Browses the nodes in server's address space, given a browse arguments object.

Public Extension MethodBrowseProperties

Browses the available properties of a specified OPC item.

Browse for available item properties. Specify machine name, server class, and item ID.

Public Extension MethodBrowseServersOverloaded. Browses for available OPC (Data Access) servers.

The server(s) can be local or can be remotely accessed via DCOM.

Public Extension MethodBrowseTreeOverloaded. Allows to traverse through OPC DA address space nodes under the specified node, using given browse arguments.
Public Extension MethodChangeItemSubscriptionOverloaded. Changes parameters of a subscription to a particular OPC item.

It is more efficient to change multiple subscriptions using IEasyDAClient.ChangeMultipleItemSubscriptions method.

Public Extension MethodGetAccessRightsPropertyValueOverloaded. Obtains value of Item Access Rights OPC property for a given OPC item.
Public Extension MethodGetAlarmAreaListPropertyValueOverloaded. Obtains value of Alarm Area List OPC property for a given OPC item.
Public Extension MethodGetAlarmQuickHelpPropertyValueOverloaded. Obtains value of Alarm Quick Help OPC property for a given OPC item.
Public Extension MethodGetChangeRateLimitPropertyValueOverloaded. Obtains value of Rate of Change Limit OPC property for a given OPC item.
Public Extension MethodGetCloseLabelPropertyValueOverloaded. Obtains value of Contact Close Label OPC property for a given OPC item.
Public Extension MethodGetConditionLogicPropertyValueOverloaded. Obtains value of Condition Logic OPC property for a given OPC item.
Public Extension MethodGetConditionStatusPropertyValueOverloaded. Obtains value of Condition Status OPC property for a given OPC item.
Public Extension MethodGetDataTypePropertyValueOverloaded. Obtains value of Item Canonical DataType OPC property for a given OPC item.
Public Extension MethodGetDeadbandPropertyValueOverloaded. Obtains value of Deadband OPC property for a given OPC item.
Public Extension MethodGetDescriptionPropertyValueOverloaded. Obtains value of Item Description OPC property for a given OPC item.
Public Extension MethodGetDeviationLimitPropertyValueOverloaded. Obtains value of Deviation Limit OPC property for a given OPC item.
Public Extension MethodGetEUInfoPropertyValueOverloaded. Obtains value of Item EUInfo OPC property for a given OPC item.
Public Extension MethodGetEUTypePropertyValueOverloaded. Obtains value of Item EU Type OPC property for a given OPC item.
Public Extension MethodGetEUUnitsPropertyValueOverloaded. Obtains value of EU Units OPC property for a given OPC item.
Public Extension MethodGetHighEUPropertyValueOverloaded. Obtains value of High EU OPC property for a given OPC item.
Public Extension MethodGetHighHighLimitPropertyValueOverloaded. Obtains value of HiHi Limit OPC property for a given OPC item.
Public Extension MethodGetHighIRPropertyValueOverloaded. Obtains value of High Instrument Range OPC property for a given OPC item.
Public Extension MethodGetHighLimitPropertyValueOverloaded. Obtains value of Hi Limit OPC property for a given OPC item.
Public Extension MethodGetItemPropertyRecordOverloaded. Obtains a DAItemPropertyRecord structure filled with OPC property values for a given OPC item.

The server(s) can be local or can be remotely accessed via DCOM.

Public Extension MethodGetLimitExceededPropertyValueOverloaded. Obtains value of Limit Exceeded OPC property for a given OPC item.
Public Extension MethodGetLowEUPropertyValueOverloaded. Obtains value of Low EU OPC property for a given OPC item.
Public Extension MethodGetLowIRPropertyValueOverloaded. Obtains value of Low Instrument Range OPC property for a given OPC item.
Public Extension MethodGetLowLimitPropertyValueOverloaded. Obtains value of Lo Limit OPC property for a given OPC item.
Public Extension MethodGetLowLowLimitPropertyValueOverloaded. Obtains value of LoLo Limit OPC property for a given OPC item.
Public Extension MethodGetMultiplePropertyValuesOverloaded. Gets values of multiple OPC properties of a specified OPC item.

This method does not throw an exception in case of OPC operation failures. Instead, the eventual exception related to each property is returned in Exception property of each returned OpcLabs.BaseLib.OperationModel.ValueResult element.

The server(s) can be local or can be remotely accessed via DCOM.

Public Extension MethodGetOpenLabelPropertyValueOverloaded. Obtains value of Contact Open Label OPC property for a given OPC item.
Public Extension MethodGetPrimaryAlarmAreaPropertyValueOverloaded. Obtains value of Primary Alarm Area OPC property for a given OPC item.
Public Extension MethodGetPropertyValueOverloaded. Gets a value of OPC property of a specified OPC item.

The server(s) can be local or can be remotely accessed via DCOM.

Public Extension MethodGetPropertyValueOverloaded. Gets a value of typed OPC property, using descriptor objects for the OPC server, node, and the property.
Public Extension MethodGetPropertyValueArrayOfBooleanOverloaded. Gets a value of OPC property, using descriptor object for the OPC server, and an OPC Item ID, and converts it to an array of System.Boolean.
Public Extension MethodGetPropertyValueArrayOfByteOverloaded. Gets a value of OPC property, using descriptor object for the OPC server, and an OPC Item ID, and converts it to an array of System.Byte.
Public Extension MethodGetPropertyValueArrayOfCharOverloaded. Gets a value of OPC property, using descriptor object for the OPC server, and an OPC Item ID, and converts it to an array of System.Char.
Public Extension MethodGetPropertyValueArrayOfDateTimeOverloaded. Gets a value of OPC property, using descriptor object for the OPC server, and an OPC Item ID, and converts it to an array of System.DateTime.
Public Extension MethodGetPropertyValueArrayOfDecimalOverloaded. Gets a value of OPC property, using descriptor object for the OPC server, and an OPC Item ID, and converts it to an array of System.Decimal.
Public Extension MethodGetPropertyValueArrayOfDoubleOverloaded. Gets a value of OPC property, using descriptor object for the OPC server, and an OPC Item ID, and converts it to an array of System.Double.
Public Extension MethodGetPropertyValueArrayOfInt16Overloaded. Gets a value of OPC property, using descriptor object for the OPC server, and an OPC Item ID, and converts it to an array of System.Int16.
Public Extension MethodGetPropertyValueArrayOfInt32Overloaded. Gets a value of OPC property, using descriptor object for the OPC server, and an OPC Item ID, and converts it to an array of System.Int32.
Public Extension MethodGetPropertyValueArrayOfInt64Overloaded. Gets a value of OPC property, using descriptor object for the OPC server, and an OPC Item ID, and converts it to an array of System.Int64.
Public Extension MethodGetPropertyValueArrayOfIntPtrOverloaded. Gets a value of OPC property, using descriptor object for the OPC server, and an OPC Item ID, and converts it to an array of System.IntPtr.
Public Extension MethodGetPropertyValueArrayOfSingleOverloaded. Gets a value of OPC property, using descriptor object for the OPC server, and an OPC Item ID, and converts it to an array of System.Single.
Public Extension MethodGetPropertyValueArrayOfStringOverloaded. Gets a value of OPC property, using descriptor object for the OPC server, and an OPC Item ID, and converts it to an array of System.String.
Public Extension MethodGetPropertyValueBooleanOverloaded. Gets a value of OPC property, using descriptor object for the OPC server, and an OPC Item ID, and converts it to System.Boolean.
Public Extension MethodGetPropertyValueByteOverloaded. Gets a value of OPC property, using descriptor object for the OPC server, and an OPC Item ID, and converts it to System.Byte.
Public Extension MethodGetPropertyValueCharOverloaded. Gets a value of OPC property, using descriptor object for the OPC server, and an OPC Item ID, and converts it to System.Char.
Public Extension MethodGetPropertyValueDateTimeOverloaded. Gets a value of OPC property, using descriptor object for the OPC server, and an OPC Item ID, and converts it to System.DateTime.
Public Extension MethodGetPropertyValueDecimalOverloaded. Gets a value of OPC property, using descriptor object for the OPC server, and an OPC Item ID, and converts it to System.Decimal.
Public Extension MethodGetPropertyValueDictionaryOverloaded. Obtains a DAPropertyValueDictionary filled with OPC property values for a given OPC item.

The server(s) can be local or can be remotely accessed via DCOM.

Public Extension MethodGetPropertyValueDoubleOverloaded. Gets a value of OPC property, using descriptor object for the OPC server, and an OPC Item ID, and converts it to System.Double.
Public Extension MethodGetPropertyValueInt16Overloaded. Gets a value of OPC property, using descriptor object for the OPC server, and an OPC Item ID, and converts it to System.Int16.
Public Extension MethodGetPropertyValueInt32Overloaded. Gets a value of OPC property, using descriptor object for the OPC server, and an OPC Item ID, and converts it to System.Int32.
Public Extension MethodGetPropertyValueInt64Overloaded. Gets a value of OPC property, using descriptor object for the OPC server, and an OPC Item ID, and converts it to System.Int64.
Public Extension MethodGetPropertyValueIntPtrOverloaded. Gets a value of OPC property, using descriptor object for the OPC server, and an OPC Item ID, and converts it to System.IntPtr.
Public Extension MethodGetPropertyValueSingleOverloaded. Gets a value of OPC property, using descriptor object for the OPC server, and an OPC Item ID, and converts it to System.Single.
Public Extension MethodGetPropertyValueStringOverloaded. Gets a value of OPC property, using descriptor object for the OPC server, and an OPC Item ID, and converts it to System.String.
Public Extension MethodGetQualityPropertyValueOverloaded. Obtains value of Item Quality OPC property for a given OPC item.
Public Extension MethodGetScanRatePropertyValueOverloaded. Obtains value of Server Scan Rate OPC property for a given OPC item.
Public Extension MethodGetSoundFilePropertyValueOverloaded. Obtains value of Sound File OPC property for a given OPC item.
Public Extension MethodGetTimestampPropertyValueOverloaded. Obtains value of Item Timestamp OPC property for a given OPC item.
Public Extension MethodGetTimeZonePropertyValueOverloaded. Obtains value of Item Timezone OPC property for a given OPC item.
Public Extension MethodGetValuePropertyValueOverloaded. Obtains value of Item Value OPC property for a given OPC item.
Public Extension MethodPullItemChangedAttempts to pull an OPC item change subscribed to by the IEasyDAClient.SubscribeMultipleItems or SubscribeItem method.
Public Extension MethodReadItemOverloaded. Reads an OPC-DA item. Value, quality and timestamp are returned.

The ReadItem method reads the data of an OPC-DA item. It uses the first available data from the server; it does not wait until the quality becomes "uncertain" or "good".

The server(s) can be local or can be remotely accessed via DCOM.

Optionally, a specific data type can be requested, or an access path can be specified (OPC DA 1.0 only).

Public Extension MethodReadItemOverloaded. Reads a typed named item from an OPC server. A typed value, quality and timestamp are returned.

The ReadItem method uses the first available data from the server; it does not wait until the quality becomes "uncertain" or "good".

The server(s) can be local or can be remotely accessed via DCOM.

Public Extension MethodReadItemValueOverloaded. Reads an OPC-DA item value. Reads a single named item from an OPC-DA server. Only the item value is returned (quality and timestamp are not returned).

Use this method if you are only interested in the actual value of the OPC item. Use ReadItem method if you also need the quality or timestamp. The ReadItemValue method makes it very easy to obtain the actual data value with just one function call.

The ReadItemValue method requires that the value quality is "good".

The server(s) can be local or can be remotely accessed via DCOM.

Optionally, a specific data type can be requested, or an access path can be specified (OPC DA 1.0 only).

Public Extension MethodReadItemValueOverloaded. Reads a typed named item from an OPC server. Only the item's typed value is returned (quality and timestamp are not returned).

Use this method if you are only interested in the actual typed value of the OPC item. Use ReadItem method if you also need the quality or timestamp. The ReadItemValue method makes it very easy to obtain the actual typed data value with just one function call.

The ReadItemValue method requires that the value quality is "good".

The server(s) can be local or can be remotely accessed via DCOM.

Public Extension MethodReadItemValueArrayOfBooleanOverloaded. Reads a value of named OPC item, and converts it to an array of System.Boolean. The value is requested from the OPC server using a corresponding data type.
Public Extension MethodReadItemValueArrayOfByteOverloaded. Reads a value of named OPC item, and converts it to an array of System.Byte. The value is requested from the OPC server using a corresponding data type.
Public Extension MethodReadItemValueArrayOfCharOverloaded. Reads a value of named OPC item, and converts it to an array of System.Char. The value is requested from the OPC server using a corresponding data type.
Public Extension MethodReadItemValueArrayOfDateTimeOverloaded. Reads a value of named OPC item, and converts it to an array of System.DateTime. The value is requested from the OPC server using a corresponding data type.
Public Extension MethodReadItemValueArrayOfDecimalOverloaded. Reads a value of named OPC item, and converts it to an array of System.Decimal. The value is requested from the OPC server using a corresponding data type.
Public Extension MethodReadItemValueArrayOfDoubleOverloaded. Reads a value of named OPC item, and converts it to an array of System.Double. The value is requested from the OPC server using a corresponding data type.
Public Extension MethodReadItemValueArrayOfInt16Overloaded. Reads a value of named OPC item, and converts it to an array of System.Int16. The value is requested from the OPC server using a corresponding data type.
Public Extension MethodReadItemValueArrayOfInt32Overloaded. Reads a value of named OPC item, and converts it to an array of System.Int32. The value is requested from the OPC server using a corresponding data type.
Public Extension MethodReadItemValueArrayOfInt64Overloaded. Reads a value of named OPC item, and converts it to an array of System.Int64. The value is requested from the OPC server using a corresponding data type.
Public Extension MethodReadItemValueArrayOfIntPtrOverloaded. Reads a value of named OPC item, and converts it to an array of System.IntPtr. The value is requested from the OPC server using a corresponding data type.
Public Extension MethodReadItemValueArrayOfSingleOverloaded. Reads a value of named OPC item, and converts it to an array of System.Single. The value is requested from the OPC server using a corresponding data type.
Public Extension MethodReadItemValueArrayOfStringOverloaded. Reads a value of named OPC item, and converts it to an array of System.String. The value is requested from the OPC server using a corresponding data type.
Public Extension MethodReadItemValueBooleanOverloaded. Reads a value of named OPC item, and converts it to System.Boolean. The value is requested from the OPC server using a corresponding data type.
Public Extension MethodReadItemValueByteOverloaded. Reads a value of named OPC item, and converts it to System.Byte. The value is requested from the OPC server using a corresponding data type.
Public Extension MethodReadItemValueCharOverloaded. Reads a value of named OPC item, and converts it to System.Char. The value is requested from the OPC server using a corresponding data type.
Public Extension MethodReadItemValueDateTimeOverloaded. Reads a value of named OPC item, and converts it to System.DateTime. The value is requested from the OPC server using a corresponding data type.
Public Extension MethodReadItemValueDecimalOverloaded. Reads a value of named OPC item, and converts it to System.Decimal. The value is requested from the OPC server using a corresponding data type.
Public Extension MethodReadItemValueDoubleOverloaded. Reads a value of named OPC item, and converts it to System.Double. The value is requested from the OPC server using a corresponding data type.
Public Extension MethodReadItemValueInt16Overloaded. Reads a value of named OPC item, and converts it to System.Int16. The value is requested from the OPC server using a corresponding data type.
Public Extension MethodReadItemValueInt32Overloaded. Reads a value of named OPC item, and converts it to System.Int32. The value is requested from the OPC server using a corresponding data type.
Public Extension MethodReadItemValueInt64Overloaded. Reads a value of named OPC item, and converts it to System.Int64. The value is requested from the OPC server using a corresponding data type.
Public Extension MethodReadItemValueIntPtrOverloaded. Reads a value of named OPC item, and converts it to System.IntPtr. The value is requested from the OPC server using a corresponding data type.
Public Extension MethodReadItemValueSingleOverloaded. Reads a value of named OPC item, and converts it to System.Single. The value is requested from the OPC server using a corresponding data type.
Public Extension MethodReadItemValueStringOverloaded. Reads a value of named OPC item, and converts it to System.String. The value is requested from the OPC server using a corresponding data type.
Public Extension MethodReadMultipleItemsOverloaded. Reads data of multiple OPC-DA items.

The ReadMultipleItems method reads the data (values, timestamps and qualities) of multiple items from one or more OPC-DA servers. It uses the first available data from the server for each item; it does not wait until the quality becomes "uncertain" or "good". The function performs all individual operations in parallel, but only returns after all individual operations are completed (or their timeouts elapse).

This method does not throw an exception in case of OPC operation failures. Instead, the eventual exception related to each item is returned in Exception property of each returned OpcLabs.EasyOpc.DataAccess.OperationModel.DAVtqResult element.

The server(s) can be local or can be remotely accessed via DCOM.

Optionally, a specific data type can be requested, or an access path can be specified (OPC DA 1.0 only).

This method operates on multiple items at once. If you only have one item, you can use the ReadItem(IEasyDAClient,DAReadItemArguments) method instead.

Public Extension MethodReadMultipleItemValuesOverloaded. Reads values of multiple OPC-DA items. Reads named items from an OPC-DA server or servers. Only the item values are returned (qualities and timestamps are not returned).

The ReadMultipleItemValues method requires that the quality is "good" for each item. The function performs all individual operations in parallel, but only returns after all individual operations are completed (or their timeouts elapse).

This method does not throw an exception in case of OPC operation failures. Instead, the eventual exception related to each item is returned in Exception property of each returned OpcLabs.EasyOpc.DataAccess.OperationModel.DAVtqResult element.

The server(s) can be local or can be remotely accessed via DCOM.

Optionally, a specific data type can be requested, or an access path can be specified (OPC DA 1.0 only).

Public Extension MethodSetState<TNode>Sets the arbitrary object associated with the node.
Public Extension MethodSubscribeItemOverloaded. Subscribe to changes of a particular OPC item.

The IEasyDAClient.ItemChanged event is generated for each significant item change.

It is more efficient to subscribe to multiple items using the SubscribeMultipleItems method.

The server(s) can be local or can be remotely accessed via DCOM.

Public Extension MethodSubscribeMultipleItemsOverloaded. Subscribe to changes of multiple OPC items.

The IEasyDAClient.ItemChanged event will be generated for each significant item change.

Public Extension MethodSupportsTechnologyDetermines whether the client object supports a given OPC technology or technologies (such as OPC COM or OPC XML).
Public Extension MethodTryEnableAutoSubscribingOptimizationAttempts to enable the auto-subscribing optimization.
Public Extension MethodUnsubscribeItem

Unsubscribe from changes of a particular OPC item.

Unsubscribe from OPC item, specifying its handle.

Public Extension MethodWaitForItemValueOverloaded. Waits until the OPC-DA item quality becomes "good".

This method subscribes to the specified OPC-DA item, and monitors its data until it has "good" quality, an error occurs, or the alloted time elapses.

The server(s) can be local or can be remotely accessed via DCOM.

Public Extension MethodWaitForMultipleItemsOverloaded. Waits until the OPC-DA items satisfy the given conditions.

Subscribes to the specified OPC-DA items, and monitors their data until the predicates specified for each item become true, or the alloted time elapses.

The server(s) can be local or can be remotely accessed via DCOM.

Public Extension MethodWaitForMultipleItemValuesOverloaded. Waits until the OPC-DA items reach the given minimum quality.

Subscribes to the specified OPC-DA items, and monitors their data until they have at least the quality specified for each item, an error occurs, or the alloted time elapses.

The server(s) can be local or can be remotely accessed via DCOM.

Public Extension MethodWriteItemOverloaded. Writes into a named item in an OPC server. Value, quality and timestamp are written.

The server(s) can be local or can be remotely accessed via DCOM.

Optionally, a specific data type can be requested, or an access path can be specified (OPC DA 1.0 only).

Public Extension MethodWriteItemOverloaded. Writes into a typed named item in an OPC server. A typed value, quality and timestamp are written.

The server(s) can be local or can be remotely accessed via DCOM.

Public Extension MethodWriteItemValueOverloaded. Writes a value into a named item in an OPC server. Only the item value is written (quality and timestamp are not written).

The WriteItemValue only writes the item value into the OPC-DA server; how the quality and timestamp are affected depends on the server. Some servers support writing the quality and timestamp as well; use the WriteItem method for that.

The server(s) can be local or can be remotely accessed via DCOM.

Optionally, a specific data type can be requested, or an access path can be specified (OPC DA 1.0 only).

Public Extension MethodWriteItemValueOverloaded. Writes a typed value into a (typed) named item in an OPC server. Only the item's typed value is written (quality and timestamp are not written).

The server(s) can be local or can be remotely accessed via DCOM.

Public Extension MethodWriteItemValueArrayOfBooleanOverloaded. Writes an array of System.Boolean value into a named OPC item. A corresponding data type is passed to the OPC server.
Public Extension MethodWriteItemValueArrayOfByteOverloaded. Writes an array of System.Byte value into a named OPC item. A corresponding data type is passed to the OPC server.
Public Extension MethodWriteItemValueArrayOfCharOverloaded. Writes an array of System.Char value into a named OPC item. A corresponding data type is passed to the OPC server.
Public Extension MethodWriteItemValueArrayOfDecimalOverloaded. Writes an array of System.Decimal value into a named OPC item. A corresponding data type is passed to the OPC server.
Public Extension MethodWriteItemValueArrayOfDoubleOverloaded. Writes an array of System.Double value into a named OPC item. A corresponding data type is passed to the OPC server.
Public Extension MethodWriteItemValueArrayOfInt16Overloaded. Writes an array of System.Int16 value into a named OPC item. A corresponding data type is passed to the OPC server.
Public Extension MethodWriteItemValueArrayOfInt32Overloaded. Writes an array of System.Int32 value into a named OPC item. A corresponding data type is passed to the OPC server.
Public Extension MethodWriteItemValueArrayOfInt64Overloaded. Writes an array of System.Int64 value into a named OPC item. A corresponding data type is passed to the OPC server.
Public Extension MethodWriteItemValueArrayOfIntPtrOverloaded. Writes an array of System.IntPtr value into a named OPC item. A corresponding data type is passed to the OPC server.
Public Extension MethodWriteItemValueArrayOfSingleOverloaded. Writes an array of System.Single value into a named OPC item. A corresponding data type is passed to the OPC server.
Public Extension MethodWriteItemValueArrayOfStringOverloaded. Writes an array of System.String value into a named OPC item. A corresponding data type is passed to the OPC server.
Public Extension MethodWriteItemValueBooleanOverloaded. Writes a System.Boolean value into a named OPC item. A corresponding data type is passed to the OPC server.
Public Extension MethodWriteItemValueByteOverloaded. Writes a System.Byte value into a named OPC item. A corresponding data type is passed to the OPC server.
Public Extension MethodWriteItemValueCharOverloaded. Writes a System.Char value into a named OPC item. A corresponding data type is passed to the OPC server.
Public Extension MethodWriteItemValueDecimalOverloaded. Writes a System.Decimal value into a named OPC item. A corresponding data type is passed to the OPC server.
Public Extension MethodWriteItemValueDoubleOverloaded. Writes a System.Double value into a named OPC item. A corresponding data type is passed to the OPC server.
Public Extension MethodWriteItemValueInt16Overloaded. Writes a System.Int16 value into a named OPC item. A corresponding data type is passed to the OPC server.
Public Extension MethodWriteItemValueInt32Overloaded. Writes a System.Int32 value into a named OPC item. A corresponding data type is passed to the OPC server.
Public Extension MethodWriteItemValueInt64Overloaded. Writes a System.Int64 value into a named OPC item. A corresponding data type is passed to the OPC server.
Public Extension MethodWriteItemValueIntPtrOverloaded. Writes a System.IntPtr value into a named OPC item. A corresponding data type is passed to the OPC server.
Public Extension MethodWriteItemValueSingleOverloaded. Writes a System.Single value into a named OPC item. A corresponding data type is passed to the OPC server.
Public Extension MethodWriteItemValueStringOverloaded. Writes a System.String value into a named OPC item. A corresponding data type is passed to the OPC server.
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Public Events
 NameDescription
Public EventDisposed (Inherited from System.ComponentModel.Component)
Public EventEventingFailureRaised when a failure in the eventing infrastructure occurs.  
Public EventItemChangedRaised for every significant change in an OPC item subscribed to by the SubscribeItem method.  
Public EventLogEntryRaised for loggable entries originating in the OPC-DA client engine and the EasyDAClient component.  
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See Also

Reference

EasyDAClientCore Class
OpcLabs.EasyOpc.DataAccess Namespace

 

 

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