Configure Real-Time Testing Applications

Publish Date: Jun 28, 2017 | 5 Ratings | 3.80 out of 5 | Print

Overview

Real-time testing involves using a real-time operating system as part of a test system. The most common requirements driving the need for a real-time test system are greater reliability and performance than is possible using a general-purpose operating system.

Table of Contents

  1. NI VeriStand for Real-Time Testing Applications
  2. Configuring Applications With NI VeriStand

1. NI VeriStand for Real-Time Testing Applications

One example is a hardware-in-the-loop (HIL) simulator for which system models must be executed deterministically to provide an accurate simulation of the components that are not physically part of the test. Applications that use closed-loop control are another type of real-time test application. These systems must automatically control a part of the test system, such as an environmental chamber, by reacting to sensor and setpoint changes deterministically to achieve the desired state of the system. They must also detect and respond to alarm conditions quickly to help prevent operator injury or test system damage. Similar to these applications, test cell stimulus and monitoring applications either already have an integrated control system or do not require closed-loop control and simply need a tool that can provide deterministic stimulus generation and test cell monitoring.

The core functionality necessary for these real-time testing applications has been implemented and optimized in the NI VeriStand architecture – ready to configure and use. This includes host interface communication, data logging, stimulus generation, alarm detection and response, and algorithm and model execution. Building on this framework, you can add custom functionality to NI VeriStand using NI LabVIEW, ANSI C/C++, and other modeling and programming environments.

By using NI VeriStand to build your real-time test systems, you benefit from reduced development time and application maintenance costs. You also benefit from the functionality and performance improvements implemented with each revision.

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2. Configuring Applications With NI VeriStand

An NI VeriStand real-time test application typically consists of one or more real-time execution targets that communicate to a host system via Ethernet. Each real-time execution target is running the NI VeriStand Engine, which is configured from the Windows-based host system and deployed over Ethernet. Once your NI VeriStand Engine configuration is deployed, you use the NI VeriStand workspace window and the tools it provides, such as the Stimulus Profile Editor, to interact with your test system at run time.

Figure 1: An overview of the NI VeriStand architecture.

When configuring and running NI VeriStand applications, you use three primary windows: the System Explorer, the Workspace, and the Stimulus Profile Editor.

System Explorer

You start by creating a system definition using the System Explorer window. The system definition contains your settings for the NI VeriStand Engine tasks such as hardware I/O as well as the functionality you import from other programming or modeling environments. You configure a system definition by adding items to the system definition tree located on the left of the System Explorer window and setting the items' configuration options in the window on the right. Once you have completed this, you deploy this system definition to your execution target and use the NI VeriStand Workspace to create a run-time interface for your test system.

Figure 2: Configure real-time testing applications using the NI VeriStand System Explorer.

Workspace

The Workspace is the user interface to a deployed system definition. With this run-time editable user interface, you place interface objects and map them to channels in your real-time application. You can use multiple Workspace screens to organize your controls and indicators into logical groups for different application tasks or simply to increase the available space of the user interface. With the user access management features, you can control access privileges for different users based on their login account.

Figure 3: Create run-time editable user interfaces using the NI VeriStand Workspace.

Stimulus Profile Editor

The Stimulus Profile Editor is an NI VeriStand tool for creating stimulus generation and logging tasks that are deployed to the NI VeriStand Engine for deterministic execution of test profiles.

Stimulus profiles are created by specifying a list of stimulus generation steps that the NI VeriStand Real-Time Engine performs. There are steps that include generating waveforms, playing back data files, and setting channel values. In addition to step-based profile creation, you can create advanced real-time profiles using a variety of constructs such as loop structures, conditional statements, variables, and yield statements. You can also add multiple logging tasks with independent logging rates and trigger conditions to your stimulus profile. For example, one log file can capture data at a reduced rate for slow-changing channels and another file can be set to acquire at a higher rate if a trigger condition occurs during the test. The NI VeriStand Stimulus Profile Editor also includes example libraries and templates to help you create real-time stimulus profiles quickly and easily.  

Stimulus profiles execute in the NI VeriStand Real-Time Engine; however, you can add more test automation capabilities from the host interface using the NI VeriStand Workspace macro recorder or by using other tools such as NI TestStand or Iron Python.

Figure 4: Create advanced real-time test profiles using the NI VeriStand Stimulus Profile Editor.

 

Workspace Tools

In addition to the Stimulus Profile Editor, the NI VeriStand Workspace includes many other tools that are useful when working with real-time testing applications. You can use these tools for monitoring alarms, calibrating hardware I/O, tuning simulation model parameters, and forcing channel values. The Workspace also features a real-time console viewer, which monitors the operation status of your real-time execution target. While these tools are natively available in NI VeriStand, you can add tools to the NI VeriStand environment using LabVIEW software.

Additional Resources

Learn More About NI VeriStand

Watch the NI VeriStand Getting Started Videos

Compare NI VeriStand Development Systems 

 

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