TestProNews Q4 - 2005
Integrate TestStand with Databases Using a Test Data Management System
TDM system users range from managers, engineers and technicians, each with different
needs depending on their job responsibilities. Because of these diverse needs, TDM
systems provide high-level analysis tools that are commonly used by all users, such
as test performance analysis. Some users need specialized engineering analysis tools
specific to their product, while others need statistical analysis tools, and still
others only need general purpose spreadsheet analysis provided by tools such as
Microsoft Excel. To meet these diverse needs, TDM systems offer a variety of methods
for interacting with analysis software so that scientists, engineers and managers
can use the best analysis tool for their application
Types of Analysis Tools
General Analysis Tools
A good example of a general analysis tool is a spreadsheet. Spreadsheets provide
a general set of functions that can be used to perform mathematical calculations.
A common spreadsheet used for analysis is Excel. Excel is ubiquitous; you will find
it on nearly every PC because it is part of the Microsoft Office suite that many
PC manufacturers preload onto every PC they sell. Excel has a wide array of capabilities
and is relatively easy to learn and use.
Tools for Interactive Engineering Analysis
Many different types of analysis software tools are available to perform special
engineering calculations, simulation and modeling. Engineers use these tools to
compare actual test data with simulated data and use the comparison to improve product
designs and shorten development cycles.
Analysis Tools for Manufacturing Test
Analysis tools are used in many electronic component manufacturing applications
to determine information about yields, how many products passed/failed, identify
the most common failure modes, etc. Manufacturing test data analysis is based heavily
on statistics, or more specifically statistical process control (SPC). The most
common SPC calculations are performed by built-in analysis functions that are an
integral part of the TDM system.
However, third-party statistical analysis software
may be used for applications that require more complex and unique statistical analysis.
Ways to Integrate Analysis Tools
Export to Analysis Software
The most common albeit crude method to integrate data into third-party analysis
software is to export the data of interest into a file format that is readable by
the software (Figure 1). ASCII data stored in comma-separated values (CSV) or tab
delimited file formats are the most common formats used to exchange TDM data with
analysis software.
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Figure 1: The most common, albeit crude method to integrate third-party analysis software is to export data in Excel, ASCII CSV or tab-delimited format readable by the software. |
To demonstrate this method, consider an application using the most popular TDM and
analysis software combination: VI Technology Arendar and Microsoft Excel. First,
you use Arendar to interactively access, filter and view test data in the database
using either a standard web browser or the Arendar Data Viewer application. Once
you have selected the data you want to use for more detailed inspection and analysis,
you use the Arendar web interface or Data Viewer to export the data from the database
into a CSV file. The TDM software's web interface and Data Viewer both simplify
the data export process by eliminating the need to write SQL statements to access
and view your test data in the database. Excel can then easily import the CSV file
for further interactive analysis.
Copy/Paste
The most simplistic method for quickly transferring test data from the database
into analysis software is to select the data of interest, copy it to the clipboard,
and paste the data into the analysis software workspace (Figure 2). To use the copy
and paste method with the Arendar TDM Web Dashboard and Excel example shown in figure
2, highlight the test data you want to analyze in your
web browser, choose "Copy",
select a cell in Excel, and choose "Paste."
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Figure 2: Copying and pasting data is the most simplistic method to get test data into the analysis software workspace. |
Send Data To Analysis Software
Some TDM software can send test data directly to analysis software
(Figure 3). In
this method, the TDM software automatically launches and sends test data to the
analysis software.
To use this method in the previously described example, use the Arendar Data Viewer
to select the data of interest and choose "Send" from the file menu. The Data Viewer
automatically launches and sends data directly to Excel or National Instrument's
DIAdem.
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Figure 3: In a more integrated TDM and analysis software solution, the TDM system automatically launches and sends data directly to the analysis software. |
Pull Data into Analysis Software from TDM Database
Most analysis tools offer a database wizard or interactive query interface to pull
data directly from a database into their workspace. Through this interface, you
can pull the data into an empty workspace or into pre-configured analysis and report
templates (Figure 4). Depending on the level of data mining capabilities integrated
into the analysis
software, the effort to pull data into the analysis software can
range from programming to interactive data selection. Pulling data directly into
the analysis software workspace is a very flexible and powerful way to access test
data in the TDM database.
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Figure 4: In an integrated TDM and analysis software solution, a TDM plug-in pulls test data directly from the database into the analysis software. |
Excel's open interface, for example, requires Visual Basic for Applications (VBA),
Structured Query Language (SQL) statements and ActiveX Data Objects (ADO) to pull
data from a database. These complexities, however, are eliminated through Arendar's
integrated Excel interface.
Other interactive analysis tools, such as DIAdem, provide a wizard that guides the
user through the steps needed to connect to the database, select the data of interest
and extract that data for further analysis.
Most analysis software products provide a way to automate data mining, analysis
and report generation tasks. The process either involves recording and playing back
a series of operator keystrokes or specifying the desired automation in a scripting
language. Through this automation, you can develop pre-configured report templates
that automatically pull the latest data from the database and create reports based
on the template.
Application Programming Interface
Some companies have legacy or proprietary software that performs analysis. In these
situations, you need a TDM system with an application-programming interface (API).
The API gives you the ability to program a custom interface to exchange data with
the legacy or proprietary analysis software.
Conclusions
Options to integrate analysis software with TDM systems range from simple "cut and
paste" procedures to fully automated analysis and report generation by directly
accessing the TDM database. Each of the options increases your productivity by giving
you the ability to efficiently analyze enormous amounts of test data in product characterization, validation and manufacturing test.
Ask the Expert
Email questions concerning this article to:
expert.testpronews@vi-tech.com
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