IOpcReadNodesService Members

Gets or sets the maximum number of nodes which shall be read using a single read request. This number indirectly defines the number of requests used to send a specific number of read requests to the server.

C#

uint? MaxNodesPerRead { get; set; }

Property Value

Nullable<UInt32>

The absolute number of read commands which shall be send to the server per request or a null reference (Nothing in Visual Basic). In case there a specific number of nodes is used, a request with more commands as the MaxNodesPerRead is partitioned into multiple requests and the responses of them are accumulated. The default value of this property is a null reference (Nothing in Visual Basic) and means that all commands defined are send to the server using the server defined number of nodes per read request.

Gets the maximum number of nodes which are read using a single read request. This property will use either the MaxNodesPerRead or the maximum number of nodes which can be read in one request as defined by the server. The lowest number of nodes is used to partition the commands to execute into multiple read requests.

C#

uint? UsedMaxNodesPerRead { get; }

Property Value

Nullable<UInt32>

In case there has already been one read attempt (with more than one read command) the definite number of commands per read request; otherwise a null reference (Nothing in Visual Basic).

Reads one or more values of one or more attributes of one or more nodes using the specified commands.

C#

IEnumerable<OpcValue> ReadNodes(IEnumerable<OpcReadNode> commands)

Parameters

commands IEnumerable<OpcReadNode>

A sequence of OpcReadNode instances to process.

Returns

IEnumerable<OpcValue>

A sequence of OpcValue instances its number and order of items matches the number and order of items in the commands sequence. There is for each command one entry which stores the value requested by that command.

Exceptions

ArgumentNullException

The commands sequence or one of its items is a null reference (Nothing in Visual Basic).

InvalidOperationException

The read service is currently not supported, especially using the commands specified.

OpcException

The service execution failed upon different circumstances; for more details see exception details. The following issues can lead to that exception: BadNothingToDo, BadTooManyOperations, BadMaxAgeInvalid and BadTimestampsToReturnInvalid.

Remarks

Known results for the commands specified are:

Reads one or more values to one or more attributes of one or more nodes using the specified commands.

C#

IEnumerable<OpcValue> ReadNodes(params OpcReadNode[] commands)

Parameters

commands OpcReadNode[]

An array of OpcReadNode instances to process.

Returns

IEnumerable<OpcValue>

A sequence of OpcValue instances its number and order of items matches the number and order of items in the commands sequence. There is for each command one entry which stores the value requested by that command.

Exceptions

ArgumentNullException

The commands array or one of its items is a null reference (Nothing in Visual Basic).

InvalidOperationException

The read service is currently not supported, especially using the commands specified.

OpcException

The service execution failed upon different circumstances; for more details see exception details. The following issues can lead to that exception: BadNothingToDo, BadTooManyOperations, BadMaxAgeInvalid and BadTimestampsToReturnInvalid.

Remarks

Known results for the commands specified are: