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DAQmx Configure Logging (TDMS) (G Dataflow)

Last Modified: May 7, 2018

Configures TDMS file logging for the task.


To maximize performance and to minimize file size, DAQmx TDMS files store raw data and scaling information separately, and do not need defragmentation. Attempting to pass a DAQmx TDMS file to the TDMS Defragment node results in an error.


task in

task in is the name of the task that the operation applies.


file path

file path specifies the path to the TDMS file to which you want to log data.


group name

group name specifies the name of the group to create, within the TDMS file, for data from this task. If you append data to an existing file and the specified group already exists, NI-DAQmx appends a number symbol and a number to the group name, incrementing that number until finding a group name that does not exist. For example, if you specify a group name of Voltage Task, and that group already exists, NI-DAQmx assigns the group name Voltage Task #1, then Voltage Task #2. If you do not specify a group name, NI-DAQmx uses the name of the task.

For digital input tasks, NI-DAQmx creates a group for each virtual channel in the task. For each created group, NI-DAQmx appends a hyphen and the virtual channel name to the group name.


logging mode

logging mode specifies whether to enable logging and whether to allow reading data while logging.

Log mode allows for the best performance. However, if you specify this mode, you cannot read data while logging. If you want to read data while logging, specify Log and Read mode.

Name Description

Disable logging for the task.


Enable logging for the task. You cannot read data using DAQmx Read when using this mode. If you require access to the data, read from the TDMS file.

Log and Read

Enable both logging and reading data for the task. You must use DAQmx Read to read samples for NI-DAQmx to stream them to disk.


error in

error in describes error conditions that occur before this node runs. This input provides standard 'error in' functionality.



operation specifies how to open the TDMS file.

Name Description

Open an existing TDMS file, and append data to that file. If the file does not exist, NI-DAQmx returns an error.

Open or Create

Open an existing TDMS file, and append data to that file. If the file does not exist, NI-DAQmx creates a new TDMS file.

Create or Replace

Create a new TDMS file, or replace an existing TDMS file.


Create a new TDMS file. If the file already exists, NI-DAQmx returns an error.


task out

task out is a reference to the task after this node runs.


error out

error out contains error information. If error in indicates that an error occurred before this node ran, error out contains the same error information. Otherwise, error out describes the error status that this node produces.

Where This Node Can Run:

Desktop OS: Windows

FPGA: LabVIEW NXG does not support FPGA devices

Web Server: Not supported in VIs that run in a web application

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