NI TDM Data Model

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Overview

Several roadblocks can get in the way of optimal exchange of technical information, the most notorious of which is the improper capture of information at the time of test or simulation. All too often data is stored, without descriptive properties, in inconsistent formats, and scattered about on arrays of computers, creating a graveyard of information that makes it extremely difficult to locate a particular data set and derive decisions from it. As a result many companies are seeing a loss in efficiency and increasing development costs.

To solve these challenges, National Instruments has defined a data model called TDM, short for Technical Data Management. There are native LabVIEW, LabVIEW Real-Time, LabWindows^TM/CVI, LabWindows^TM/CVI Real-Time, and DIAdem interfaces for reading and writing TDM files.  These interfaces abstract the complexity of storing structured data, while also making it conducive to easily add descriptive information along with captured measurement or simulation data. The additional descriptive information makes TDM files search ready, ensuring that the technical data is well documented. In addition, there is an Add-in for Microsoft Excel for reading TDM files into Excel, and C libraries available for reading and writing TDM files in other tools and programming environments.

Working with the TDM data model in LabVIEW

In LabVIEW there are two different APIs for interacting with the TDM Data Model. The fastest and most flexible is the TDM Streaming API, introduced in LabVIEW 8.20, which writes TDMS files, (the S in TDMS stands for streaming). The other TDM interface is through the LabVIEW Data Storage VIs, introduced in LabVIEW 7.1, which write a flavor of TDM files, using an XML-based header file.

See Also:
Whitepaper: Overview of all NI TDM Technologies
Application Note: Using the TDM Streaming API
Application note: Using the LabVIEW Data Storage VIs to read and write TDM files
Web resource: Learn more about LabVIEW

Working with the TDM data model in LabWindows/CVI

In LabWindows/CVI there are two different API for interacting with the TDM Data Model. The fastest and most flexible is the TDM Streaming Library, introduced in LabWindows/CVI 8.1, which writes TDMS files. The other TDM interface is through the DIAdem Connectivity Library, introduced in LabWindows/CVI, which writes TDM files.

See Also:
Whitepaper: Introduction to the LabWindows/CVI TDM Streaming
Webcast: Best Practices for Data Storage and Retrieval with LabWindows/CVI

Mining TDM files using DIAdem

The DIAdem DataFinder is revolutionizing how engineers and scientists work with their data. Not only can you locate the data you need to work with faster, you now have the ability to search for patterns and trends that were not previously possible when your data was saved in flat files scattered across the lab. Adopting the TDM file format and the DIAdem DataFinder increases the value of your collected data and has a dramatic impact shortening the product development cycle. Learn more on how you can benefit from DIAdem and the DIAdem DataFinder technology.

See Also:
Video tutorial: Mining test data using the DIAdem DataFinder (with voice)
Video tutorial: Mining test data using the DIAdem DataFinder (text only)
Video tutorial: Learn more about the Analysis and Reporting Capabilities of DIAdem
Web resource: Learn more about DIAdem

Loading TDM files into Excel

Using the FREE Microsoft Excel Add-in, you can load and work with TDM and TDMS files in Excel.

See Also:
Download the Free Excel Add-in for loading TDM files into Excel

Loading TDM files into OpenOffice.org Calc

Using the FREE OpenOffice.org Calc Add-in, you can load and work with TDM and TDM files in Calc.

See Also:
Download the Free OpenOffice.org Calc Add-in for loading TDM files into Calc

Using DataPlugins

DataPlugins extend the data file loading capabilities of DIAdem and LabVIEW by providing translators that map the contents of any arbitrary data file onto the TDM data model. DataPlugins make all data files regardless of format available for mining using DIAdem. You can create your own DataPlugins for use in LabVIEW and DIAdem or choose from a list of DataPlugins to download.

See Also:
Download DataPlugins and read the DataPlugins programmers reference guide

Background Information about the TDM File Format

The TDM File Format

NI TDM (Technical Data Management) file format is a structured, search-ready format that utilizes XML to manage a wide range of attributes associated with each data file. The TDM format is designed to capture and manage all the important information surrounding a measurement or simulation, assuring that the data is self explanatory, reusable, and requires no additional explanation to recreate the conditions in which it was captured.

The TDM data model defines 3 levels of hierarchy, as the Root, Group and Channel objects. Each file has a single root object, and any number of group and channel objects. For example in one file you may choose to save the original data in group 1 named “raw data”, and create a second group called “analyzed results” to separate the analyzed results from the original data. Within each group the measurement or simulation data is saved in channels which are 2D arrays of numeric or string data types. Each of the three levels has an unlimited number of associated properties. For example, you may want to save the sensor id as a property associated with each channel, and save the UUT number at the root level.

The TDM file format offers several unique benefits such as the ability to scale to your specific project requirements and easily attach descriptive information to your test or simulation data. The use of XML makes TDM files easily searchable and portable between applications.

Integrating TDM into non NI Software Tools

If you are interested in integrating reading and writing TDM into your software application, and you are not using LabVIEW, LabWindows/CVI or DIAdem,  you can use the TDM C DLL to read and write TDM and TDMS files. Please contact Caroline Bright, NI Software Product Manager, with any questions.

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