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Get Waveform Attribute (G Dataflow)

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Last Modified: August 21, 2019

Retrieves either the value of a single waveform attribute or the names and values of all waveform attributes.

To retrieve the names and values of all attributes, select Get All Attributes in the Behavior section of the Item tab.

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waveform

Waveform for which you want to retrieve the attribute and value.

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name

The name of the attribute whose value you want to retrieve.

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Note  

This input is not available if you click this node on the diagram and select Get All Attributes in the Behavior section of the Item tab.

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default value

A value and data type that you specify. If the node does not find the attribute specified in name, it returns the default value.

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Note  

This input is not available if you click this node on the diagram and select Get All Attributes in the Behavior section of the Item tab.

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error in

Error conditions that occur before this node runs.

The node responds to this input according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Default: No error

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duplicate waveform

Waveform data you input in waveform.

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found

A Boolean value that indicates whether the node found the attribute that is specified in name.

True The node found the attribute specified in name.
False The node did not find the attribute specified in name.
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Note  

This output is replaced by a 1D array output containing the names of all of the attributes if you click this node on the diagram and select Get All Attributes in the Behavior section of the Item tab.

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names

A 1D array containing the names of all attributes associated with the waveform.

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Note  

This output is only available if you click this node on the diagram and select Get All Attributes in the Behavior section of the Item tab.

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value

The value associated with the attribute you wire to name.

If the node does not find the attribute specified in name, it returns the value passed to default value.

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Note  

This output is replaced by a 1D array output containing the values of all of the attributes if you click this node on the diagram and select Get All Attributes in the Behavior section of the Item tab.

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values

A 1D array containing the values associated with each attribute of the waveform.

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Note  

This output is only available if you click this node on the diagram and select Get All Attributes in the Behavior section of the Item tab.

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error out

Error information.

The node produces this output according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Modes of Behavior

This node has two modes of behavior depending on whether you select Get All Attributes in the Behavior section of the Item tab.

Get All Attributes Node Behavior
Selected The node returns the names of all attributes and their corresponding values in 1D arrays.
Not selected The node searches for only the specified attribute. The names output changes to a Boolean output called found and the values output changes to a variant output called value. If the node does not find the specified attribute(s), or if it cannot convert the attribute(s) to the default value, found is False, and value displays the contents of default value.

Waveform Attributes Set by DAQmx

Waveform signals obtained from a DAQ device include specific waveform attributes whose data you can access in your program. The following table lists the waveform attributes set by DAQmx.

Attribute Name Data Type Acceptable Values Description
Name of Channel NI_ChannelName String Any value NI_ChannelName is the name of the virtual channel producing the waveform.
Name of Digital Line(s) NI_LineNames String Any value NI_LineNames is the name of the digital line in the waveform.
Unit for Data NI_UnitDescription String Volts, PSI, etc. NI_UnitDescription is the units of measure for the waveform.
Decibel Reference NI_dBReference Double Finite values greater than zero NI_dBReference is the reference value to use when converting measurement levels to decibel.

Where This Node Can Run:

Desktop OS: Windows

FPGA: Not supported

Web Server: Supported in VIs that run in a web application

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