Table Of Contents
TDMS Set Properties (G Dataflow)
Sets the properties of a .tdms file, group, or channel. You must close the reference to the .tdms file or flush data to the .tdms file for changes to take effect.
Copyright: (c) 2016 National Instruments. All rights reserved.
property values
Property values of the .tdms file, group, or channel.
Acceptable Data Types
This input accepts the following data types:
- Signed and unsigned integer
- Single-precision or double-precision floating-point number
- Complex single-precision or double-precision floating-point number
- Extended-precision floating-point number
- Alphanumeric string that does not contain null characters
- Timestamp
- Boolean
- Variant that contains any of the data types specified above
property names
Property names of the .tdms file, group, or channel.
tdms file
A reference to a .tdms file. Use the TDMS Open node to obtain the reference.
group name
Channel group on which to perform the operation.
If you wire a value to channel name, you must also wire a value to group name.
channel name
Channel on which to perform the operation.
If you wire a value to channel name, you must also wire a value to group name.
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.
Default: No error
tdms file out
A reference to the .tdms file.
group name out
Channel group on which you performed the operation.
channel name out
Channel on which you performed the operation.
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.
Searching at the File, Group, or Channel Level
The following table shows the inputs you must wire to search for properties at the file, group, or channel level.
| Search level | Required Inputs | Comments |
|---|---|---|
| File or root level | None | Leave group name and channel name empty to search at the file or root level. |
| Group level | group name | |
| Channel level | group name and channel name | If channel name contains a value, group name must also contain a value. |
Setting Multiple Properties
To set multiple properties using the same node, you can wire a 1D array of an acceptable data types to property values. Each value in the array corresponds to a single property. However, a single property cannot hold an array of values.
Properties in a .tdms File
The following table lists all properties you might find in a .tdms file.
| Property Name | Data Type | Access | Available in File Format Versions | Description |
|---|---|---|---|---|
| name | String | Read/write | 2.0 | Specifies the object name, such as the root name, group name, or channel name, in a .tdms file. |
| NI_ArrayColumn | 32-bit signed integer numeric | Read only | 1.0 and 2.0 | Indicates the index of a column in a 2D array. This property appears in a .tdms file only if you write a 2D array of data to the file. |
| NI_ChannelLength | 64-bit unsigned integer numeric | Read only | 1.0 and 2.0 | Represents the number of values in a channel of a .tdms file. |
| NI_DataType | 16-bit unsigned integer numeric | Read only | 1.0 and 2.0 | Represents the data type of a channel. The value is an integer that corresponds to a type code. |
| NI_DigitalCompression | Boolean | Read only | 1.0 and 2.0 | Indicates whether a digital table is compressed or not. A value of 1 indicates that the digital table is compressed. If the digital table is not compressed, this property does not appear. |
| NI_DigitalLine | 32-bit signed integer numeric | Read only | 1.0 and 2.0 | Indicates the index of a row in a digital table. |
| NI_DigitalNumberOfLines | 32-bit signed integer numeric | Read only | 1.0 and 2.0 | Indicates the number of rows in a digital table. |
| NI_Number_Of_Scales | 32-bit unsigned integer numeric | Read/write | 2.0 | Specifies the number of scales to use when you read data from a .tdms file. For example, if a .tdms file has five scales and you set the value of NI_Number_Of_Scales to 4, only the first four scales are applied to the data when you read the .tdms file. |
| NI_Scale[n]_config, where n represents the order of the scale and config represents the configuration of the scale. | N/A | Read/write | 2.0 | Specifies the scaling information for the data in a .tdms file. You can create more than one scale in a .tdms file. |
| NI_Scaling_Status | String | Read/write | 2.0 | Specifies whether to scale data when reading the data from a .tdms file. If the value is unscaled and the .tdms file contains one or more scales, the data is scaled. If the value is scaled, the data is not scaled. |
| unit_string | String | Read/write | 1.0 and 2.0 | Specifies the unit of the channel data in a .tdms file. |
| wf_increment | Double | Read/write | 1.0 and 2.0 | Represents the increment between two consecutive samples on the x-axis. |
| wf_samples | 32-bit signed integer numeric | Read/write | 1.0 and 2.0 | Represents the number of samples in the first data chunk of the waveform you write to a .tdms file. The value must be greater than zero. |
| wf_start_offset | Double | Read only | 1.0 and 2.0 | Frequency-domain data and histogram results use this value as the first value on the x-axis. |
| wf_start_time | Timestamp | Read only | 1.0 and 2.0 | Represents the time at which the waveform was acquired or generated. This property can be zero if the time information is relative or the waveform is not in time domain. |
| wf_time_pref | String | Read only | 1.0 and 2.0 | Indicates whether to interpret the x-axis data in absolute time or relative time. |
| wf_xname | String | Read only | 1.0 and 2.0 | Indicates the name of the x-axis of the waveform. |
| wf_xunit_string | String | Read only | 1.0 and 2.0 | Indicates the unit text of the x-axis. |
If the data type of a property is not valid, this node treats the property as a customized property and the property will not perform as described in the table.
Additional Properties that Affect .tdms Data and Performance
The following table lists all properties that do not exist in a .tdms file, but which you can use to perform certain actions.
| Property Name | Data Type | Access | Available in File Format Versions | Description |
|---|---|---|---|---|
| NI_DiskCacheSize | 32-bit unsigned integer numeric | Read/write | 2.0 | You can use the NI_DiskCacheSize property to improve the .tdms data writing performance by allocating a specific amount of cache size in memory for the data. .tdms data is written in bytes per file. This property is valid only when the disable buffering input of the TDMS Open node is TRUE. The default value for this property is approximately 2 MB. Wire a different value to the property values input of the TDMS Set Properties node to change the cache size. A greater value for the NI_DiskCacheSize property usually can improve the writing performance; however, a greater value also requires more computer resources. |
| NI_DiskGapSize | 32-bit unsigned integer numeric | Read/write | 2.0 | You can use the NI_DiskGapSize property to improve the .tdms data reading performance when reading discontinuous data. This property is valid only when the disable buffering input of the TDMS Open node is TRUE. The value of the NI_DiskGapSize property is a multiple of the sector size of the local hard disk. The default value for this property is 10. If the data gap in the .tdms file is less than the value of the NI_DiskGapSize property, the TDMS Read node can read all data from the file at one time. If the data gap in the .tdms file is greater than the value of the NI_DiskGapSize property, the TDMS Read node reads each piece of data one at a time until this node finishes reading all data. Wire a value to the property values input of the TDMS Set Properties node to change the gap size. |
| NI_MinimumBufferSize | 32-bit unsigned integer numeric | Read/write | 1.0 and 2.0 | You can use the NI_MinimumBufferSize property to improve the .tdms data writing performance by writing to a file less often. This property can reduce the size of a .tdms file by controlling the number of times the data is written to disk. The NI_MinimumBufferSize property is valid only if the data layout input of the TDMS Write node is non-interleaved. By default, the value of the NI_MinimumBufferSize property is zero. If you set the value at the group level, this node also sets the value of underlying channels whose value is zero. If you set the value at the file level, this node also sets the value of underlying groups and channels whose value is zero. Use of this property and the NI_DiskCacheSize property affects file buffering with .tdms files. |
| NI_UpdateChannelName | String | Write only | 1.0 and 2.0 | You can use the TDMS Set Properties node to rename groups and channels in .tdms files. Wire NI_UpdateGroupName to the property names input if you want to rename a group and wire NI_UpdateChannelName to the property names input if you want to rename a channel. Wire the new group or channel names to the property values input and wire the group or channel names that you want to replace to the group name or channel name input. If the groups or channels you wire to group name or channel name do not exist, new groups or channels are created with the new names. |
| NI_UpdateGroupName |
Where This Node Can Run:
Desktop OS: Windows
FPGA: DAQExpress does not support FPGA devices