Data Acquisition, DAQ

How a system integrator developed a data acquisition application

System integrator DMC developed a custom LabVIEW data acquisition application to leverage SystemLink as a central database for storing and serving up data for data analysis and visualization

By Ryan Yu November 28, 2020
Courtesy: DMC

Developed by National Instruments, SystemLink is a software platform designed to help companies manage devices, software and test data on a centralized SystemLink server. SystemLink provides a wide variety of powerful, built-in management tools that make it easier for users to manage their fleet of test hardware and gain key insights into their test systems. SystemLink provides flexible options for data storage in the form of data files and tags, which make it simple to upload test data onto the SystemLink server. Once the data is in the SystemLink environment, a wide variety of data analysis and data visualization tools become available to the user, allowing one to maximize the information gained from the test data.

This case study highlights a recent project where DMC developed a custom LabVIEW data acquisition application to leverage SystemLink as a central database for storing and serving up data for data analysis and visualization. The solution DMC delivered provided the client with a custom LabVIEW test executive specific to its operational processes and business needs. At the same time, the LabVIEW application sent data to a custom-configured SystemLink server, which gave the client the flexibility to manage test systems and data in ways that helped add value to the testing workflows.

Assessing the situation

This solution was implemented for the client’s quality assurance testing lab. The lab is large, and units are spread out. The client wanted to replace one computer for data management with a server allowing remote access through the web on the same network or from home. This remote capability now offers more options on how to view and access the data. While this project was completed prior to the COVID-19 pandemic, the system enabled engineers to access data anywhere they can access their network.

The client had an existing data acquisition system that suffered from the following data management issues:

  • Local data storage
  • No backups were taken, so data was at risk
  • The data was not secure and there were critical security vulnerabilities
  • The database grew unmanaged over time, so it suffered from slow data write and export speeds
  • Off-the-shelf data acquisition software could not support the data throughput and acquisition rates required by changing industry requirements
  • Operators were bottlenecked in their daily tasks due to the single user-access point on the one PC hosting the local data
  • The database offered limited data management tools, so getting insights from the data was difficult
  • Data was aliased according to the physical channel it was acquired on, so handwritten notes were needed to associate a physical channel with the meaningful metadata of the test
  • Data was cumbersome to visualize and response rates for the interface were slow.

Four-step approach

The client searched for a solution that could gather high-speed test data from its fleet of remote NI cDAQ devices and store the data in a secure and centralized location. The client also wanted a solution to accommodate multiuser remote access and provide tools for organizing, searching, analyzing and reporting the data. Based on these requirements, DMC designed a four-step approach that leveraged SystemLink’s data management tools to accomplish these goals.

Step 1: Test the executive app. DMC worked to develop a test executive that would fit well into its existing testing workflow. DMC began by designing a flexible test executive for configuring and controlling the data acquisition hardware. This was a LabVIEW application that ran on local computers (nodes) connected to the data acquisition devices. These “nodes” provide a local interface to the data and allow operators to configure hardware settings, configure data acquisition parameters, start new tests and view live results in high resolution.

To send data from the nodes up to the SystemLink server to leverage the different features it provides, DMC developed a code module called the “data destination.” The data destination is an object-oriented class designed to be a generic and flexible application programming interface (API) for the test executive to store acquired data in different locations. SystemLink data destinations were implemented to allow the test executive to automatically send data to the SystemLink server in the form of data files (for high-speed data) and SystemLink tags (for calculated data and metrics).

Step 2: SystemLink data destinations. SystemLink has two options for data storage, files and tags. The file storage on the SystemLink server is enhanced and optimized by its software. The server provides a centralized and secure option for storing data files and the SystemLink File Transfer toolkit can be used to programmatically transfer files from a custom LabVIEW application to the server. DMC developed a SystemLink technical data management system (TDMS) driver based on this API to save and format high-speed test data to TDMS files and transfer them automatically to the client’s SystemLink server during testing. The API relies on HTTPS and SystemLink’s system management feature to validate and securely transfer files (see Figure 1).

Figure 1: The API relies on HTTPS and SystemLink’s system management feature to validate and securely transfer files. Courtesy: DMC

Figure 1: The API relies on HTTPS and SystemLink’s system management feature to validate and securely transfer files. Courtesy: DMC

The tag feature is useful for storing slower speed data such as metrics and health data. The tag viewer in the web user interface (UI) makes it easy to view the latest tag data as it is being updated live and the tags are great for monitoring and tracking ongoing tests. The aggregate feature enables historical recording of tags values that can be viewed through the tag viewer, as well.

Features such as keywords and properties allow the user to attach metadata to the tags for easier organization and filtering during searches. The tags toolkit provides the tools necessary to create, configure and interact with tags in the LabVIEW environment.

For this project, DMC created the SystemLink Tag driver to calculate test metrics and post them to SystemLink tags for general test monitoring. Tags were created dynamically from the custom LabVIEW application so that by the time they were published to the server, they were ready to be consumed by end users who were looking to understand their tests (see Figure 2).

Figure 2: Tags were created dynamically from the custom LabVIEW application so that by the time they were published to the SystemLink server, they were ready to be consumed by end users who were looking to understand their tests. Courtesy: DMC

Figure 2: Tags were created dynamically from the custom LabVIEW application so that by the time they were published to the SystemLink server, they were ready to be consumed by end users who were looking to understand their tests. Courtesy: DMC

Step 3: SystemLink server setup. An important consideration of integrating SystemLink into any project is the specification of the server itself. The performance of the server depends on the CPU, RAM and drive selected for the server hardware. Data throughput, the duration of tests and data retention periods should be considered to calculate how much disk space the SystemLink server needs to accommodate the data collected in the lifetime of a system.

DMC worked with the client to calculate the hardware specifications needed for a high performing data storage solution. It also benchmarked the file transfer and tag writing features using a SystemLink test server to ensure the application would meet or exceed the client’s requirements. The final proposed server hardware was designed to last for years of testing and high-speed data collection.

Step 4: SystemLink features. Once test data is stored on the SystemLink server in the form of data files and tags, SystemLink’s data management tools become available to the user. The web interface allows simultaneous multiuser access to the tools and stored data. The web interface also can be configured to require user authentication at different user levels for security purposes. The TDMS test data can be accessed and viewed in the web interface using the file viewer tool, which also provides additional filtering and data manipulation features. Tag data can be viewed through the tag viewer and can be used to create test dashboards or queried by the test monitor to produce test insights.

SystemLink’s systems manager tool allowed DMC to set up asset management for the client’s test nodes. This unlocked the ability to push software updates to the nodes through the web interface and easily track metrics such as connection status and CPU usage. Calibration tracking also can be configured for managed assets to notify users based on calibration schedules. The asset management provided the user with the ability to ensure configuration conformity across assets and view the status of an entire fleet of test systems in one place.

Overall, DMC provided the client with a solution delivering the following features that resolved many of the issues with the previous data management system:

  • Centralized data storage on a server with backup options
  • Secure data transfer
  • Improved data storage security
  • Multiple data storage methods for both slow and high-speed data
  • Simultaneous multiuser access
  • Access to a broad selection of data management and analysis tools.

Final thoughts

With the test executive and SystemLink integration, DMC was able to deliver a fully featured data acquisition and data management system to its client. The system allowed the client to centralize its data and rely on the tools to secure, manage and analyze the data. SystemLink updates the old data storage infrastructure into a, server-based infrastructure that updates the data management quickly and easily.

DMC is a member of the Control System Integrators Association (CSIA).


Ryan Yu
Author Bio: Ryan Yu is a systems engineer at DMC.