Table Of Contents

TDMS Read (G Dataflow)

Last Modified: March 8, 2017

Reads data from a .tdms file.

Copyright: (c) 2016 National Instruments. All rights reserved.

connector_pane_image
datatype_icon

count

Maximum number of data elements to read for each channel.

Default: -1 — Causes this node to read all available elements.

datatype_icon

offset

Number of data elements into the .tdms file at which this node begins to read.

Default: 0

datatype_icon

tdms file

A reference to a .tdms file. Use the TDMS Open node to obtain the reference.

datatype_icon

group name in

Channel group on which to perform the operation.

Reading Behavior When group name in Is Not Wired

If you do not wire data to group name in, this node reads data from the current group in the file. The current group is either the first group in the file when you run this node for the first time or the nth group at the nth cycle when you run this node continuously for multiple cycles. The order that this node reads groups is the same order that the TDMS List Contents node returns groups. If this node attempts to run after reaching the last group, you receive an end of file error.

spd-note-note
Note  

The TDMS List Contents node and the TDMS Get Properties node reset the current group to the first group in the file. Resetting the current group to the first group in the file impacts the group read by the next TDMS Read node when you do not wire group name in.

datatype_icon

channel name(s) in

Channel or channels to read data from.

channel name(s) in accepts a string or a 1D array of strings. The data type varies according to the data you wire to data type.

Determining the Data Type of channel name(s) in

The following table shows how the data type of channel name(s) in varies according to the data you wire to data type.

data type channel name(s) in
  • Analog waveform
  • 1D array of:
    • Signed or unsigned integers
    • Floating-point numbers
    • Timestamps
    • Booleans
    • Alphanumeric strings that do not contain null characters
String
  • Digital waveform
  • Digital table
  • 1D array of analog waveforms
  • 2D array of:
    • Signed or unsigned integers
    • Floating-point numbers
    • Timestamps
    • Booleans
    • Alphanumeric strings that do not contain null characters
1D Array of Strings

Reading Behavior When channel name(s) in Is Not Wired

If you do not wire data to channel name(s) in, this node reads data from all channels under the same group and returns data channels in the same order as they exist in the .tdms file.

Reading Compressed Digital Data

If you load a complete file or group that contains compressed digital data, this node automatically inserts the compression channel name in the channel name(s) in array. If you load a subset of a file or group that contains compressed digital data, you must enter the name of the compression channel as the first entry in the channel name(s) in array.

datatype_icon

error in

Error conditions that occur before this node runs. The node responds to this input according to standard error behavior.

Default: No error

datatype_icon

data type

The type of data you want the node to return.

Acceptable Data Types

This input accepts the following data types:

  • Analog waveform or a 1D array of analog waveforms
  • Digital waveform
  • Digital table
  • 1D or 2D array of:
    • Signed or unsigned integers
    • Floating-point numbers, including the following specific data types:
      • Single-precision and double-precision floating-point numbers
      • Complex single-precision and double-precision floating-point numbers
      • Extended-precision floating-point numbers
    • Timestamps
    • Booleans
    • Alphanumeric strings that do not contain null characters
datatype_icon

return channels in file order

A Boolean specifying whether the node returns data channels in the same order as they exist in the .tdms file.

TRUE Return data channels in the same order as they exist in the .tdms file.
FALSE Return data channels in the same order as you specify in channel name(s) in.

Default: FALSE

datatype_icon

tdms file out

A reference to the .tdms file.

datatype_icon

group name out

Channel group on which you performed the operation.

datatype_icon

channel name(s) out

Channel or channels on which you performed the operation.

datatype_icon

data

Data that the node read from the .tdms file.

If data has scaling information, the node automatically scales the data.

datatype_icon

error out

Error information. The node produces this output according to standard error behavior.

datatype_icon

end of file?

A Boolean that indicates whether the node has reached the end of the file.

TRUE The node has reached the end of the file.
FALSE The node has not reached the end of the file while reading data.

Where This Node Can Run:

Desktop OS: Windows

FPGA: Not supported


Recently Viewed Topics