1. technology and computing
2. programming languages

What Is NI TestStand?
Overview
NI TestStand is ready-to-run test management software designed to help you develop automated test and validation
systems faster. You can use NI TestStand to develop, execute, and deploy test system software. In addition, you can
develop test sequences that integrate code modules written in any test programming language. Sequences also
specify execution flow, reporting, database logging, and connectivity to other enterprise systems. Finally, you can
deploy test systems to production with easy-to-use operator interfaces.
Table of Contents
1. Developing Test Systems with NI TestStand
2.
Deploying Test Systems with NI TestStand
3.
Where Would I Use NI TestStand?
4.
Conclusion
Developing Test Systems with NI TestStand
NI TestStand includes the Sequence Editor development environment for automated test system development, as
seen in Figure 1.
Figure 1. The NI TestStand Sequence Editor helps you develop automated test systems faster.
With the Sequence Editor, you can create test sequences, which automate the execution of code modules written in
any programming language. Each code module executes a test on the device under test and returns measurement
information to NI TestStand. You can log test result information in a report or database automatically. In addition,
systems written in NI TestStand can integrate with source code control, requirements management, and data
management systems.
Watch this four-minute demo to discover how you can develop automated test systems with NI TestStand.
Deploying Test Systems with NI TestStand
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After development is complete, you can use NI TestStand to deploy automated test systems to production. NI
TestStand helps deployment by providing simple operator interfaces that can execute the test system and reduce
operator error. You can create operator interfaces, like the one seen in Figure 2, in a number of different
programming languages to meet a variety of application requirements.
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Figure 2. You can create simple operator interfaces to execute test systems.
NI TestStand also offers a deployment utility, which helps you create a distribution of code modules, test sequences,
and related files. You can copy this distribution to a central code repository or directly to a production machine, or you
can include it in an installer.
Where Would I Use NI TestStand?
NI TestStand automates a sequence of steps. These steps can be individual tests, measurements, actions, or
commands. Any application needing automation of executable pieces of code can benefit from the use of NI
TestStand. NI TestStand was designed to address four key areas: (1) simplify complex sequence development; (2)
accelerate complex sequence development; (3) increase code and test system reusability and maintenance; and (4)
improve test system execution performance. This has led to its adoption in consumer electronics for validation and
manufacturing test, military and aerospace applications, and the medical industry, as well as IC characterization
and simple code sequencing.
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Figure 3. This diagram shows where NI TestStand fits into the development and manufacturing cycle.
Read more in the “Where Would I Use NI TestStand?” white paper.
NI TestStand in the Electronics Industry
The electronics industry has to meet high test-throughput challenges. Device production can increase quickly,
requiring test systems to scale and test more units in less time. Using NI TestStand, engineers in the electronics
industry can develop test systems quickly to reduce time to market. NI TestStand parallel test features also help
engineers develop scalable test systems that can increase, as necessary, the number of devices tested in parallel.
Learn more about how Flextronics saved millions of dollars and met its test-throughput challenges using NI
TestStand.
NI TestStand in the Aerospace and Defense Industry
Engineers in the aerospace industry face the challenge of testing some of the most complex and innovative devices
today. With NI TestStand, engineers can rely on a commercial off-the-shelf tool that is compatible with industry
standards such as ATML, IVI, PXI, ATLAS, and others. In addition, the modular architecture of NI TestStand helps
reduce obsolescence by supporting the execution of both legacy and next-generation programming languages in the
same test system.
See how Lockheed Martin used NI TestStand to standardize the test architecture for the Joint Strike Fighter.
Conclusion
NI TestStand offers a flexible and powerful framework for developing, managing, and executing test systems. The
components of NI TestStand work together and seamlessly integrate the features of enterprise systems and software.
As test management software, NI TestStand delivers easy integration of independent test modules into a testing
framework. With this easy integration, you can focus on developing tests instead of the test framework needed to
build the test system.
NI TestStand is an integral part of any test where accelerated development, code reusability, improved performance,
and automation are desired. It offers a ready-to-run yet fully customizable environment for developing and managing
test systems.
What's New in NI TestStand 4.2
Questions? Get real-time assistance now!
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Upgrade to NI TestStand 4.2 Now
Reduce test system development time with NI TestStand 4.2 by reusing your existing software investment in NI
LabVIEW, NI LabWindows™/CVI, scripting languages, and .NET with a commercial test executive. With faster
deployment of LabVIEW code, better integration with scripting languages such as Perl and Python, and Visual Studio
2008 support, you can now integrate different software more easily into NI TestStand.
Improved Integration with LabVIEW, .NET, and Scripting Languages
Simplified Integration with Scripting Languages
The redesigned Call Executable step type provides a more powerful interface for calling common scripting languages
such as Python, Perl, and Tcl.
Read the in-depth white paper
Accelerated Deployment of LabVIEW Files in NI TestStand
The NI TestStand 4.2 deployment utility uses improved internal caching to accelerate the analysis and build time of
deployments.
Validation of LabVIEW Code Modules
The new software engineering tools for LabVIEW can help you ensure the quality and reliability of your LabVIEW
code.
Support for Visual Studio 2008
NI TestStand 4.2 supports direct integration with Visual Studio 2008 and the ability to target the .NET 3.5 framework.
Memory Leak Detection with LabWindows/CVI
The new Resource Tracking Window in LabWindows/CVI 9.0 can help you identify places where memory was
allocated but not released.
View webcast on the new NI TestStand 4.2 features
Improved Report Performance and Customization
Report Path Customization Using Expressions
NI TestStand 4.2 gives you the ability to use expressions to customize the path where reports are stored.
Faster XML Style Sheet Performance and Enhanced Documentation
XML report style sheets have been completely restructured to enhance report generation efficiency and
customization.
Processor Affinity Control for Improving Multicore Performance
With new functionality for controlling processor and core affinity, you have tools to optimize symmetric
multiprocessing system performance.
Support for PropertyObject Attributes
The new PropertyObject attributes, available for any PropertyObject, let you store additional information about
PropertyObjects.
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Automated Test Equipment: Instrumentation, Software, Services,
and Integrators
National Instruments offers a complete software and hardware platform, allowing you to build a software-defined test
system that meets your exact test requirements. With this platform, you gain the assurance of ongoing technology
support and the flexibility to customize your instrumentation as your needs change. NI offers service programs for
individual engineers, global organizations, integrators, and OEMs. These services are designed to meet your needs
throughout the application life cycle – from planning and development through deployment and ongoing maintenance.
NI supplies this framework through its modular, automated test platform shown below. Select individual components
to learn more about these instruments. Or, view example reference test systems that employ software-defined
architecture.
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http://zone.ni.com/devzone/cda/tut/p/id/8847
Calling Scripting Languages from NI TestStand
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Overview
The ability to re-use existing code while migrating to a new test software framework can save developers both time
and money. Both NI TestStand test management software and NI LabVIEW give users the ability to directly call and
integrate with code written in a variety of languages such as Perl, Python and Tcl.
NI TestStand, starting with version 4.2, has the ability to call your scripts written in languages such as Perl, Python
and Tcl using the Call Executable step type. In particular, NI TestStand can pass data in and out of scripts as well as
access the script’s error information.

Passing Data to Scripts:
Developers can pass data from TestStand to their scripts either through command line arguments or directly through
the Standard Input stream. Using the Standard Input stream allows developers to reuse scripts that traditionally took
user input from the keyboard during run-time, and run it in an automated fashion from TestStand.

Accessing Output in TestStand:
Once the execution of the script is complete, anything that the script wrote to the Standard Output can be accessed
from the TestStand sequence. This will enable developers to base the status of a step on the result of a script.

Accessing Script Errors in TestStand:
If an error occurred during execution of the script, the error information is also available to TestStand through the
Standard Error stream. This enables developers to handle the error appropriately.
What this means is that developers can effectively utilize the full power of their scripts by taking advantage of the
hooks that TestStand provides to the executable’s Standard Input (stdin), Standard Output (stdout) and Standard
Error (stderr).
This article is Part 2 of a three-part series on calling scripting languages from TestStand with a focus on the needs of
engineers and scientists.
Table of Contents
1. Calling a Simple Script from TestStand
2.
Accessing Script Outputs from TestStand: Standard Output
3.
Passing Data to Scripts from TestStand: Command Line
4.
Passing Data to Scripts from TestStand: Standard Input
5.
Evaluating Script Results: Pass/Fail Test using Status Expression
6.
Evaluating Script Results: Numeric Limit Test using <None> Adaptor
7.
Handling Script Errors in TestStand
8.
Next Steps
Calling a Simple Script from TestStand
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Getting Started
If you are new to scripting or don’t have an interpreter installed, we recommend reading Part 1 of this series:
Developer Zone Tutorial: Introduction to Scripting
Also, if you are looking to call scripts from LabVIEW, instead of NI TestStand, you can use the System Exec VI. For a
tutorial, refer to:
Developer Zone Tutorial: Call Perl and Python Scripts from LabVIEW
In order to call
a script from TestStand you will have to have the following:

A script to call (we will use examples in Perl, Python and Tcl)

An interpreter for the scripting language you choose

The NI TestStand Sequence Editor (or an Operator Interface that allows you to modify sequences)
If you are currently part of the National Instruments Standard Service Program, you can also access the interactive
training module on calling scripts from TestStand here:
On Demand Training: TestStand Modules
The Script: HelloWorld
The script used in this example is a simple HelloWorld script that will simply write “Hello World!” to the Standard
Output stream.
Note: You can download any of the script files by clicking on their filename above the code snippets.
Perl: HelloWorld.pl
#!/usr/bin/perl -w
use strict;
print "Hello World!\n";
Python: HelloWorld.py
#!/usr/bin/env python
print "Hello World!"
Tcl: HelloWorld.tcl
#!/bin/sh
# -*- tcl -*# The next line is executed by /bin/sh, but not tcl \
exec tclsh "$0" ${1+"$@"}
puts "Hello World!";
Calling the HelloWorld Script from TestStand
The process of calling a script from TestStand is very similar to calling it from the Windows command line. In fact, all
you have to do is use the Call Executable step and specify the path and file for the script you want to execute. (The
reason this works is because we associated the script file extension with the appropriate interpreter. If you haven’t
associated the script file with a particular interpreter, you will have to specify the interpreter as the executable and
pass in the script file as a command line argument).
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1.
Open the NI TestStand Sequence Editor and a new sequence file.
2.
Add a Call Executable step and rename it “Call HelloWorld Script”.
3.
On the Step Settings pane, switch to the Call Settings tab.
4.
Specify the name of the script you want to call in the File PathName
Perl: HelloWorld.pl
Python: HelloWorld.py
Tcl: HelloWorld.tcl
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5.
Save the sequence file as CallingHelloWorld.seq in the same folder as the script.
6.
Run your sequence file. Your report should say that the test passed and that the Call Executable script had
an ExitCode of 0, which indicates success.
Note: If you haven’t associated the script file’s extension with the appropriate interpreter, you will have to call the
interpreter directly from the Call Executable step and pass in the script as a command line argument. See the
following screenshot for an example:
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Accessing Script Outputs from TestStand: Standard Output
Most programming languages define a standard output stream that programs can write their output to. While this
standard output stream (stdout) defaults to the terminal (monitor), NI TestStand gives you the ability to access the
standard output stream from the Call Executable Step type.
In the following example, you will learn how to use the previous Hello World example and modify it so that you can
write the output of the script to your TestStand report.
Accessing the Standard Output Stream from TestStand
We will use the same HelloWorld script and continue from the same sequence CallingHelloWorld sequence that you
created in the previous section, Calling a Simple Script from TestStand.
1.
Open the sequence file CallingHelloWorld.seq.
2.
Highlight the “Call HelloWorld Script” step.
3.
On the Step Setting pane, switch to the Standard Output/Error tab.
4.
On the Output Destination combo box, pick Store in Variable/Property.
Leave the default value, i.e., Step.StdOutput.Text.
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5.
On the Step Settings pane, switch to the Properties tab and select the Additional Resultscategory.
6.
Click the Add Result from List button and select Standard Output. This will include the stdout stream in
the report.
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7.
Save the sequence file as CallingHelloWorldWithStdOut.seq in the same folder as the script.
8.
Run your sequence file. Your report should look like the following screenshot:
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Passing Data to Scripts from TestStand: Command Line
Most programming languages allow you to pass data to them when you launch them through command line
arguments – extra parameters that you type in after the name of the script on the command line. TestStand’s Call
Executable step allows you to pass parameters to your scripts in this method.
The Script: AddNumbersCommandLine
This is a fairly basic script that will accept a series of numbers as command line arguments and writes their sum to
the standard output stream.
Perl: AddNumbersCommandLine.pl
#!/usr/bin/perl –w
use strict;
#Command Line Arguements are stored in list @ARGV
my $numArgs = $#ARGV + 1;
my $sum = 0;
#Iterate through each element and add to the sum
foreach my $currentNumber (@ARGV)
{
$sum += $currentNumber;
}
print "Sum: ", $sum, "\n";
Python: AddNumbersCommandLine.py
#!/usr/bin/env python
import sys
#Command Line Arguements are stored in list argv
numArgs = len(sys.argv) - 1
sum = 0
#Iterate through each element and add to the sum
for n in range (1, len(sys.argv)):
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sum = sum + int(sys.argv[n])
print "Sum:", sum, "\n"
Tcl: AddNumbersCommandLine.tcl
#!/bin/sh
# -*- tcl -*# The next line is executed by /bin/sh, but not tcl \
exec tclsh "$0" ${1+"$@"}
#Command Line Arguements are stored in list argv
set numArgs $argc
set sum 0
#Iterate through each element and add to the sum
foreach currentNumber $argv {
set sum [expr $sum + $currentNumber]
}
puts "Sum: $sum\n"
Passing Command Line Arguments from TestStand
All you need to do in order to pass Command Line Arguments from TestStand to a script is to include the parameters
you want to pass in the Argument Expression field of the Call Executable step.
1.
Create a new sequence file.
2.
Add a Call Executable step and name it “Call AddNumbersCommandLine Script”.
3.
On the Step Settings pane, switch to the Call Settings tab.
4.
Point the File Pathname field to the appropriate AddNumbersCommandLine script.
5.
For the Argument Expression field, enter in a series of numbers enclosed in double-quotes. For example:
“2 5 8”
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6.
Switch to the Standard Output tab and store the output in the Variable/PropertyStep.StdOutput.Text.
7.
On the Step Settings pane, switch to the Properties tab and select the Additional Resultscategory.
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8.
Click the Add Result from List button and select Arguments. This will include the command line
arguments in the report.
9.
Click the Add Result from List button and select Standard Output. This will include the stdout stream in
the report.
10. Save the sequence file as PassingDataToScriptsCommandLine.seq in the same folder as the script.
11. Run your sequence file. Your report should look like the following screenshot:
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Passing Data to Scripts from TestStand: Standard Input
Most programming languages also define a standard user input stream that programs can read from during
execution. While this standard input stream (stdin) defaults to the keyboard, NI TestStand gives you the ability to
access the standard input stream from your sequence. This gives developers more flexibility as your scripts can read
these values during run-time rather than right when they begin execution.
The Script: AddNumbersStdIn
Perl: AddNumbersStdIn.pl
#!/usr/bin/perl -w
use strict;
print "Enter numbers (separate with commas): ";
#Get input as a string
my $numbersAsString = <STDIN>;
#Parse the numbers into a list
my @numbers = split(/, | |,/,$numbersAsString);
my $sum = 0;
#Iterate through the list and add to the sum
foreach my $currentNumber (@numbers)
{
$sum += $currentNumber;
}
print "Sum: ", $sum, "\n";
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Python: AddNumbersStdIn.py
#!/usr/bin/env python
#Get input as a list
numbers = raw_input('Enter numbers (separate with commas): ')
sum = 0
#Iterate through the list and add to the sum
for currentNumber in numbers:
sum = sum + currentNumber
print "Sum:", sum, "\n"
Tcl: AddNumbersStdIn.tcl
#!/bin/sh
# -*- tcl -*# The next line is executed by /bin/sh, but not tcl \
exec tclsh "$0" ${1+"$@"}
puts "Enter numbers (separate with commas): "
#Get input as a string
gets stdin numbersAsString
#Parse the numbers into a list
set numbers [split $numbersAsString ,]
set sum 0
#Iterate through the list and add to the sum
foreach currentNumber $numbers {
set sum [expr $sum + $currentNumber]
}
puts "Sum: $sum\n"
Passing Data through the Standard Input from TestStand
All you need to do in order access the standard input stream from TestStand is to enable an Input Method on
the Standard Input tab of the Call Executable step.
1.
Create a new sequence file.
2.
Add a Call Executable step and name it “Call AddNumbersStdIn Script”.
3.
On the Step Settings pane, switch to the Call Settings tab.
4.
Point the File Pathname field to the appropriate AddNumbersStdIn script.
5.
On the Step Settings pane, switch to the Standard Input tab.
6.
Switch the Input Method combo box to String, and enter in a series of numbers separated by commas. For
example:
2, 5, 8
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7.
Switch to the Standard Output tab and store the output in the Variable/PropertyStep.StdOutput.Text.
8.
On the Step Settings pane, switch to the Properties tab and select the Additional Resultscategory.
9.
Click the Add Result from List button and select Standard Input. This will include the stdin stream in the
report.
10. Click the Add Result from List button and select Standard Output. This will include the stdout stream in
the report.
11. Save the sequence file as PassingDataToScriptsStdIn.seq in the same folder as the script.
12. Run your sequence file. Your report should look like the following screenshot:
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Evaluating Script Results: Pass/Fail Test using Status Expression
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The earlier topics discussed how to get the output of a script into TestStand using the Standard Output stream. Once
you have this data in your sequence, NI TestStand gives you the ability to base the result of your sequence based on
this output. One way to do this is to modify the Status Expression of the Call Executable step.
The Script: IsVoltageInRange
This simple script takes in a range as an input (minimum and maximum) through the standard input stream. It then
compares a simulated voltage which is hardcoded to 5V to the range and prints “Result: True” or “Result: False” to
the standard output.
Perl: IsVoltageInRange.pl
#!/usr/bin/perl -w
use strict;
#Simulated Voltage
my $voltage = 5;
#Get Range
print "Enter range (separate with commas): ";
my $numbersAsString = <STDIN>;
my @numbers = split(/, | |,/,$numbersAsString);
my $min = $numbers[0];
my $max = $numbers[1];
if ($voltage >= $min && $voltage <= $max)
{
print "Result: True\n"
}
else
{
print "Result: False\n"
}
Python: IsVoltageInRange.py
#!/usr/bin/env python
#Simulated Voltage
voltage = 5
#Get Range
numbers = input('Enter range (separate with commas): ')
min = numbers[0]
max = numbers[1]
if voltage > min and voltage <= max:
print "Result: True\n"
else:
print "Result: False\n"
Tcl: IsVoltageInRange.tcl
#!/bin/sh
# -*- tcl -*# The next line is executed by /bin/sh, but not tcl \
exec tclsh "$0" ${1+"$@"}
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#Simulated Voltage
set voltage 5
#Get Range
puts "Enter range (separate with commas): "
gets stdin numbersAsString
set numbers [split $numbersAsString ,]
set min [lindex $numbers 0]
set max [lindex $numbers 1]
if {$voltage >= $min && $voltage <= $max} {
puts "Result: True\n"
} else {
puts "Result: False\n"
}
Evaluating Output in TestStand using Status Expression
Since you know that the script is going to return either “Result: True” or “Result: False”, you can use a status
expression to parse for this string in the standard output stream and set the step status based on the output.
1.
Create a new sequence file.
2.
Add a Call Executable step and name it “Pass/Fail Test: IsVoltageInRange (Pass)”.
3.
On the Step Settings pane, switch to the Call Settings tab.
4.
Point the File Pathname field to the appropriate IsVoltageInRange script.
5.
On the Step Settings pane, switch to the Standard Input tab.
6.
Switch the Input Method combo box to String, and enter in a range that will pass separated by commas.
For example:
2, 8
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7.
Switch to the Standard Output tab and store the output in the Variable/PropertyStep.StdOutput.Text.
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8.
Create a Boolean local variable named Locals.isVoltageInRage.
9.
On the Step Settings pane, switch to the Properties tab and select the Expressionscategory.
10. Enter the following Post-Expression to parse the standard output:
Locals.isVoltageInRange =
(Find(Step.StdOutput.Text, "Result: True") > 0) ? True : False
11. Enter the following Status-Expression to set the result of the step:
Step.Result.Status = Locals.isVoltageInRange ? "Passed" : "Failed"
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12. On the Additional Results category, enable Standard Input and Standard Output using theAdd Result
From List button. This will include the stdin and stdout stream in the report.
13. Click the Add Custom Result button and enter in “isVoltageInRange” as the Name and
“Locals.isVoltageInRange” as the Value to Log. Make sure the Type reads Boolean.
14. Now create a copy of the step and insert it right after the original step. Name the copy “Pass/Fail Test:
IsVoltageInRange (Fail)”.
Modify the Standard Input in this step to cause a fail condition. For example:
3, 4
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15. Save the sequence file as PassFailTestStatusExpression.seq in the same folder as the script.
16. Run your sequence file. Your report should look like the following screenshot:
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Evaluating Script Results: Numeric Limit Test using <None> Adaptor
The earlier topics discussed how to get the output of a script into TestStand using the Standard Output stream. Once
you have this data in your sequence, NI TestStand gives you the ability to base the result of your sequence based on
this output. One way to do this is to use Test Step with a <None> Adaptor after the script to evaluate the script’s
output.
The Script: GetVoltage
This script simply creates simulated voltage reading which is hardcoded to 5V to the range and prints “Voltage:
<voltage>” to the standard output.
Perl: GetVoltage.pl
#!/usr/bin/perl -w
use strict;
#Simulated Voltage
my $voltage = 5;
print "Voltage: " , $voltage, "\n"
Python: GetVoltage.py
#!/usr/bin/env python
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#Simulated Voltage
voltage = 5
print "Voltage:", voltage, "\n"
Tcl: GetVoltage.tcl
#!/bin/sh
# -*- tcl -*# The next line is executed by /bin/sh, but not tcl \
exec tclsh "$0" ${1+"$@"}
#Simulated voltage
set voltage 5
puts "Voltage: $voltage\n"
Evaluating Output in TestStand using <None> Adaptor
Since you know that your script is going to return either the voltage in the format “Voltage: <voltage>, you can use a
status expression to parse for this string in the standard output stream and set a local variable to this value.
Then, you can use a Numeric Limit Test with a <None> Adaptor to test the output.
1.
Create a new sequence file.
2.
Add a Call Executable step and name it “GetVoltage”.
3.
On the Step Settings pane, switch to the Call Settings tab.
4.
Point the File Pathname field to the appropriate GetVoltage script.
5.
On the Step Settings pane, switch to the Standard Input tab.
6.
Switch to the Standard Output tab and store the output in the Variable/PropertyStep.StdOutput.Text.
7.
Create a numeric local variable named Locals.voltage.
8.
On the Step Settings pane, switch to the Properties tab and select the Expressionscategory.
9.
Enter the following Post-Expression to parse the standard output:
Locals.voltage =
Val(
Mid(
Step.StdOutput.Text,
Find(Step.StdOutput.Text, "Voltage: ") + Len("Voltage: "),
Find(Step.StdOutput.Text, "\n", Find(Step.StdOutput.Text, "Voltage: "))
- (Find(Step.StdOutput.Text, "Voltage: ")) + Len("Voltage")
)
)
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10. On the Additional Results category, enable Standard Output using the Add Result From List button.
This will include the stdout stream in the report.
11. Click the Add Custom Result button and enter in “Voltage” as the Name and Locals.voltage as the Value
to Log. Make sure the Type reads Number.
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12. Now pick <None> from the Adaptor dropdown list and a Numeric Limit Test step. Name the step “Numeric
Limit Test: IsVoltageInRange (Pass)”.
13. Set the Data Source for this step to Locals.voltage.
14. Set the Limits of the step to a range that covers 5 so that the test will pass. For example:
Low: 3
High: 8
15. Now create a copy of the two steps and insert them right after the original steps. Name the copy of the
Numeric Limit Test “Numeric Limit Test: IsVoltageInRange (Fail)”.
Modify the Limits on this step to cause a fail condition. For example:
Low: 3
High: 4
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16. Save the sequence file as NumericLimitTestNoneAdaptor.seq in the same folder as the script.
17. Run your sequence file. Your report should look like the following screenshot:
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Handling Script Errors in TestStand
Finally, NI TestStand also gives you access to the Standard Error (stderr) stream. Anytime an error occurs in your
Perl, Python or Tcl scripts, they will write out to this stream. Using this, you can handle any errors eloquently in your
TestStand sequence.
The Script: AddNumbersWithErrorHandling
This is a modified version of our AddNumbersStdIn script that will check to make sure that all the inputs were numeric
values; otherwise it will throw an error, write to the stderr stream and exit with ExitCode -1.
Perl: AddNumbersWithErrorHandling.pl
#!/usr/bin/perl -w
use strict;
print "Enter numbers (separate with commas): ";
my $numbersAsString = <STDIN>;
my @numbers = split(/, | |,/,$numbersAsString);
my $sum = 0;
foreach my $currentNumber (@numbers)
{
die("Input is not a number!, stopped") unless ($currentNumber =~ /^\d+$/);
$sum += $currentNumber ;
}
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print "Sum: ", $sum, "\n";
Python: AddNumbersWithErrorHandling.py
#!/usr/bin/env python
import sys
try:
numbers = input('Enter numbers (separate with commas): ')
except:
print >> sys.stderr, 'Input is not a number!'
sys.exit(-1)
sum = 0
for currentNumber in numbers:
sum = sum + currentNumber
print "Sum:", sum, "\n"
Tcl: AddNumbersWithErrorHandling.tcl
#!/bin/sh
# -*- tcl -*# The next line is executed by /bin/sh, but not tcl \
exec tclsh "$0" ${1+"$@"}
puts "Enter numbers (separate with commas): "
gets stdin numbersAsString
set numbers [split $numbersAsString ,]
set sum 0
foreach currentNumber $numbers {
if ![string is integer -strict $currentNumber] {
#error "Input is not a number!"
puts stderr "Input is not a number!"
return -1
}
set sum [expr $sum + $currentNumber]
}
puts "Sum: $sum\n"
Handling Script Errors in TestStand
TestStand makes it easy not only to access the Standard Error stream in our sequence, but also makes it easy to
make decisions based on the contents of this stream and eloquently handle any errors.
1.
Create a new sequence file.
2.
Add a Call Executable step and name it “Call AddNumbers Script (Correct Input)”.
3.
On the Step Settings pane, switch to the Call Settings tab.
4.
Point the File Pathname field to the appropriate AddNumbersWithErrorHandling script.
5.
On the Step Settings pane, switch to the Standard Input tab.
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6.
Switch the Input Method combo box to String, and enter in a series of numbers separated by commas. For
example:
2, 5, 8
7.
Switch to the Standard Output tab and store the output in the Variable/PropertyStep.StdOutput.Text.
8.
Enable the Standard Error by switching the Error Destination dropdown to Store in Value/Property. Leave
the default destination, Step.StdError.Text.
9.
Check the Set Error.Msg to Standard Error Test checkbox.
10. Switch the If Standard Error is Non-Empty dropdown to Set Step Status to Error.
11. On the Step Settings pane, switch to the Properties tab and select the Additional Resultscategory.
12. Click the Add Result from List button and add Standard Input, Standard Output and Standard Error.
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13. Now create a copy of the step and insert it right after the original step. Name the copy “Call AddNumbers
Script (Incorrect Input)”.
Modify the Standard Input in this step to cause an error condition. For example:
2, Five, 8
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14. Save the sequence file as HandlingScriptErrors.seq in the same folder as the script.
15. Run your sequence file. Your report should look like the following screenshot:
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Next Steps
Now that you know how to integrate simple scripts into TestStand sequences, the next article will show you how to
create more complex scripts that can call DLLs, perform data acquisition in NI-DAQmx and communicate with
instruments using NI-VISA.
Developer Zone Tutorial: Advanced Scripting in Perl, Python and Tcl
If you are currently enrolled in the Standard Service Program, you can also access the interactive training module on
calling scripts from TestStand here:
On Demand Training: TestStand Modules
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