Get Properties Express VI

Owning Palette: Storage/DataPlugin VIs

Requires: Base Development System (Windows)

Reads property values from a file, channel group, or channel. If you configure this Express VI before you wire a refnum to storage refnum, the configuration might change depending on the refnum you wire. For example, if you configure this Express VI for a channel and then wire a channel group refnum, this Express VI returns broken wires on the block diagram because the same properties are not available for a channel group.

Example

Dialog Box Options

Block Diagram Inputs

Block Diagram Outputs

Add to the block diagram

Find on the palette

Dialog Box Options

Parameter	Description
Settings	Contains the following options: Object type—Specifies the type of data for which you want to get properties. File—Reads properties from a file. Channel group—Reads properties from a channel group. Channel—Reads properties from a channel.
Properties	Contains the following options: TDM Properties—Use the TDM Properties tab to edit predefined properties and create user-defined properties for .tdm and .tdms files. Click the Insert button to add a new property to configure. Click the Delete button to remove the selected property. For predefined properties, you can edit only the Source and Value columns. Source—Use the Source column to specify the input source of the property information. The Source column contains the following options: Terminal—Select this option if you want to specify the property information on the block diagram. Ignore—Select this option if you do not want to write any of the property information on the specified row to the file. Name—Use the Name column to specify the property name. The property name cannot contain any spaces or special characters. LabVIEW automatically replaces spaces and special characters with an underscore. This column contains the following predefined property names: Name—Specifies the name of the object you select in Object type. Description—Specifies the description of the object you select in Object type. Title—Specifies the title of the data set in the .tdm or .tdms file. This property appears only if you select File in Object type. Author—Specifies the author of the data set in the .tdm or .tdms file. This property appears only if you select File in Object type. Time stamp—Specifies the time and date information when you last saved the data set in the .tdm or .tdms file. This property appears only if you select File in Object type. Channel groups—Specifies the channel group objects for the data set in the .tdm or .tdms file. This property appears only if you select File in Object type. File—Specifies the file object for the channel group. This property appears only if you select Channel group in Object type. Channels—Specifies the channel objects for the channel group. This property appears only if you select Channel group in Object type. Channel group—Specifies the channel group object for the data channel. This property appears only if you select Channel in Object type. Unit—Specifies the unit of the channel values. This property appears only if you select Channel in Object type. Data type—Specifies the data type of the channel values. This property appears only if you select Channel in Object type. Minimum—Specifies the lowest channel value. This property appears only if you select Channel in Object type. Maximum—Specifies the highest channel value. This property appears only if you select Channel in Object type. Waveform length—Specifies the number of samples in the waveform. This property appears only if you select Channel in Object type. Waveform x dimension—Specifies the name of the x dimension of the waveform. This property appears only if you select Channel in Object type. Waveform x unit—Specifies the unit of the x dimension of the waveform. This property appears only if you select Channel in Object type. Waveform timestamp—Specifies the time stamp of the first sample in the waveform. This property appears only if you select Channel in Object type. Waveform offset—Specifies the starting point in the waveform. This property appears only if you select Channel in Object type. Waveform increment—Specifies the time interval between every two adjacent samples in the waveform. This property appears only if you select Channel in Object type. Waveform time mode—Specifies the time mode of the waveform. You can specify either an absolute or relative time mode. This property appears only if you select Channel in Object type. Value—Use the Value column to specify the property value. The format of Value is determined by your selection in the Data Type column. The value in this column is not used if you selected the Terminal option in the Source column. Data Type—Use the Data Type column to specify the data type of the Value column. The Data Type column contains the following options: STR—Select this option to specify Value as a string. DBL—Select this option to specify Value as a double-precision, floating-point number. TIME—Select this option to specify Value as a timestamp value. I32—Select this option to specify Value as a long integer number. Insert—Inserts a new input at the top of the list. Delete—Deletes the selected input from the list. DAQmx—Use the DAQmx Properties tab to select and edit DAQmx property names for .tdm and .tdms files.
Measured data channel	Contains the following options: Show terminals for data channel—Displays terminals for Signal, index, and count on the block diagram. Output data channel as—Specifies the data type of the output. This option is available only if you select Channel as the Object type and if you place a checkmark in the Show terminals for data channel check box. Dynamic data type—Returns the output signal formatted as dynamic data. Waveform—Returns the output signal formatted as a waveform. Array of strings—Returns the output signal formatted as a 1D array of strings. Array of doubles—Returns the output signal formatted as a 1D array of double-precision, floating-point numbers. Array of singles—Returns the output signal formatted as a 1D array of single-precision, floating-point numbers. Array of I32—Returns the output signal formatted as a 1D array of 32-bit signed integers. Array of I16—Returns the output signal formatted as a 1D array of 16-bit signed integers. Array of U8—Returns the output signal formatted as a 1D array of 8-bit unsigned integers. Array of time stamps—Returns the output signal as a 1D array of time stamp values.

Block Diagram Inputs

Parameter	Description
storage refnum	Specifies the reference number for the data object you want to access. After you wire a file refnum to this input, the label changes from storage refnum to storage refnum (file). After you wire a channel group refnum to this input, the label changes from storage refnum to storage refnum (channel group). After you wire a channel refnum to this input, the label changes from storage refnum to storage refnum (channel).
error in	Describes error conditions that occur before this node runs.
index	Specifies where this Express VI starts reading values from a channel. This input appears only if you select Channel as the Object type and if you place a checkmark in the Show terminals for data channel check box in the configuration dialog box.
count	Specifies the number of values for this Express VI to read from a channel. This input appears only if you select Channel as the Object type and if you place a checkmark in the Show terminals for data channel check box in the configuration dialog box.

Block Diagram Outputs

Parameter	Description
storage refnum	Returns a reference number for the data object this Express VI accesses. You can wire this refnum to another VI to complete another operation on the same object.
Signal	Returns a signal formatted according to the data type you specified in the configuration dialog box. This output appears only if you select Channel as the Object type and if you place a checkmark in the Show terminals for data channel check box in the configuration dialog box.
error out	Contains error information. This output provides standard error out functionality.

Example

Refer to the TDM Channel Groups.lvproj in the labview\examples\File IO\DataPlugins\TDM\TDM Channel Groups directory for an example of using the Get Properties Express VI.

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