Data Acquisition Software: The Brains Behind the Hardware

0
93
Keysight DAQs

What is data acquisition software?

Fig 1. Types of data acquisition software

Data acquisition software consists of onboard and remote components that facilitate configuration, collection, visualisation, and analysis of measurements from data acquisition systems and other DAQ hardware like add-on modules.

DAQ software includes:

  • the onboard firmware, which includes applications running on an embedded operating system and controlled from the DAQ system’s screen
  • applications, like the PathWave BenchVue Data Acquisition App, and libraries that run on a remote computer or a mobile device

The illustration above shows the various types of DAQ software.

What are the key features and functionalities of comprehensive data acquisition software?

Pathwave Benchvue Data Acquisition App | Key Features and Functionalities of Comprehensive Data Acquisition Software

Fig 2. PathWave BenchVue Data Acquisition App

In this section, we explain some features that are essential in DAQ software for streamlined testing and effective data handling. These generally apply to both onboard firmware and remote software unless stated otherwise.

Intuitive and efficient user interface

Since the main goals of DAQ systems are streamlining and scaling your testing, intuitive and efficient user interfaces are critical. Users must be able to easily configure possibly hundreds of measurement channels quickly. The software must do low-level configuration validations (like ensuring that voltage ranges are correct) as well as higher-level configuration validations across channels (like ensuring that the sampling rates of a test point’s voltage and current channels match for accurate power readings) to ensure that there are no conflicts or abnormalities in the overall configuration.

Support for multiple DAQ systems and add-ons

For scalability, remote DAQ software must support connecting multiple DAQ systems to a single test station. It must also coordinate actions between them, like controlling programmable power supplies to the DUT during measurements.

Going down a level, DAQ systems acquire data from a variety of modules like multiplexers, digitisers, and more. Their firmware must smoothly identify and run with any type of add-on module and any number of them up to its maximum number of slots.

Sensor configuration

Good DAQ software programs must be cognizant of the various nuances of different transducers. For example, they can ensure that thermocouples are properly connected to the screw terminals by measuring the channel resistance after each thermocouple measurement. Similarly, they can set reference junction temperatures for each temperature-sensing transducer like a thermocouple or a resistance temperature detector (RTD).

Channel configuration

For efficiency, DAQ software must provide convenient configuration tools for high-channel-count DAQ systems. It must allow every measurement channel to be configured for a particular scenario. Parameters like the number of power line cycles for noise reduction using integration over samples or the channel delay must be configurable.

Channel scanning

Before a measurement scan, a scan list that includes all the desired multiplexer or digital channels must be configured using the DAQ software.

The DAQ software coordinates the measurements over the scan list, which may include channels from multiple DAQ systems. During a scan, each DAQ system connects its built-in multimeter to the specified multiplexer channels one at a time through relays and measures each channel according to the configured sampling rate.

Computed or virtual channels

DAQ software must allow users to configure computed or virtual channels by specifying various math functions to apply to channel measurements in real-time. Some DAQ software programs even allow completely arbitrary equations to be entered with validation.

Automation and test sequences

Testing is often a carefully coordinated dance of interleaved actions, events, and measurements across multiple instruments and devices. DAQ software must allow such complex test sequences to be created, preferably through some kind of graphical flow diagramming tools. These sequences must be fully automated so that they become repeatable and reproducible.

Deployment and connectivity options

Centralized and Distributed Daq Deployments | Deployment and Connectivity Options

Fig 3. Centralized and distributed DAQ deployments

DAQ software must support both centralized and distributed DAQ deployments of data acquisition devices.

It must allow connectivity through all the common interfaces like:

  • local area network (LAN), usually over wired Ethernet
  • universal serial bus (USB)
  • general purpose interface bus (GPIB)

Data logging, analysis, and visualisation

DAQ software programs allow the configuration of trigger criteria, like alarms and threshold values, to enable or disable data logging. They also provide real-time visualisation of the measured data as well as sophisticated statistical and mathematical data analyses on the data to draw insights.

How does data acquisition software interface with sensors and other hardware to capture data?

Modular Daq System With Add-on Measurement Modules on the Right

Fig 4. A modular DAQ system with add-on measurement modules on the right

Most of the measurement circuitry and sensors are built into add-on modules, like the DAQM900A multiplexer, which are connected to the device under test and then simply plugged into an empty slot of a DAQ system like the DAQ970A.

The DAQ system’s onboard firmware senses this module, its onboard sensors, and their capabilities. It then notifies the remote DAQ software over LAN or USB.

The DAQ software displays the configurable parameters of that particular add-on module and its connected channels to the user. When the user configures the channels, the configuration is sent back to the DAQ system using the standard commands for programmable instruments (SCPI). The DAQ system’s firmware then uses internal mechanisms to inform the add-on module’s firmware about the new configuration.

When the user tells the DAQ software to start measurements, other SCPI commands are sent to the DAQ system and from there to the add-on module.

How does data acquisition software support real-time data acquisition?

We can study some real-world examples from the automotive industry to get insights into how DAQ software facilitate real-time data acquisition:

  • Critical temperature measurements: DAQ systems and software can be used to monitor and profile temperature and voltage changes of lithium-ion batteries for electric vehicles with hundreds of channels measuring temperature changes at four test points on each cell in real-time as the batteries are charged and discharged.
  • Power measurements: DAQ systems can be used to characterise the thermal resistances of metal-oxide-semiconductor field-effect transistors used in automotive power electronics. The DAQ software enables fast, continuous, and synchronous measurements of both voltages and currents to determine the resistances.
  • Automated tests: DAQ systems can automate the functional testing of electronic control units using the highly modular 34980A DAQ system and its built-in web application.

How does data acquisition software handle signal processing and data filtering?

Signal Processing Configuration for Measurement Channels in Benchvue

Fig 5. Signal processing configuration for measurement channels in BenchVue

Onboard DAQ firmware as well as remote DAQ software provide the following signal-processing and data-filtering capabilities to ensure the accuracy and reliability of acquired data:

  • Signal processing: DAQ firmware as well as remote DAQ software allow the customisation of the signal conditioning applied to the raw analog inputs coming from the transducers. Parameters related to the built-in attenuators, amplifiers, or linearizers can be adjusted. For example, BenchVue can customise the signal conditioning applied to the integrated electronics piezo-electric (IEPE) accelerometers of Keysight DAQM909A modules that are used for measurement applications such as harmonic and noise distortion, power analysis, and acoustic characterisation of electromechanical devices.
  • Noise reduction: Techniques like differential inputs can be specified to reduce the noise in the readings.
  • Data filtering: Measurements like the total harmonic distortion (THD), THD plus noise, and signal-to-noise and distortion (SINAD) in the frequency domain provide additional hints on the reliability of the measured data.

How does data acquisition software facilitate specific testing scenarios?

The primary goal of DAQ systems and software is to streamline all types of testing, particularly high-volume production testing. So they have capabilities that enable them to be flexible enough for a variety of testing scenarios. These features include:

  • the ability to control multiple DAQ systems at the same time
  • full configuration of measurement channels for a particular test scenario, like their measured parameter (voltage, current, resistance, or something else), scaling, sampling rates, couplings, number of samples, and much more for dynamic data acquisition
  • the ability to save and load the channel configurations for repetitive and reproducible testing across geographies and time

What data analysis and visualisation features are included in data acquisition software?

DAQ software provides a variety of tools to interpret and visualise the acquired data as explained below.

Time domain charts

The Time Domain Chart Feature of Benchvue

Fig 6. The time domain chart feature of BenchVue

Time domain charts enable engineers to plot readings from multiple channels to visualise changes in parameters over time as well as correlate the changes in different channels.

Frequency domain charts

Software Interface | Frequency Domain Analysis Using Benchvue

Fig 7. Frequency domain analysis using BenchVue

For applications like vibration analysis, engineers often need to visualise the changes in the frequency domain to interpret the data correctly. DAQ software programs have built-in fast Fourier transform (FFT) analyzers to decompose and visualise the changes by frequency as shown above.

Two-channel charts

Two-Channel Chart in Benchvue

Fig 8. Two-channel chart in BenchVue

These charts enable you to visualise the correlation between two channels by plotting one on the X-axis and the other on the Y-axis.

Other visualisations

DAQ software provides a variety of other visualisations as graphical gadgets that you can add to the user interface based on your requirements and convenience. These include:

  • digital data visualisations
  • strip charts
  • histograms and bar meters
  • data grids
  • key readings

How does data acquisition software facilitate long-term monitoring?

For long-term monitoring of endurance tests and the like, data acquisition software must implement some essential features:

  • Data logging: DAQ software must provide fine-grained control over the criteria for enabling data recording and the durations of recording.
  • Data storage: The data from a long-term test is likely to exceed most local storage capacities. Plus, if the local storage fails, all that valuable measurement data is lost forever. So DAQ software must periodically compress, transfer, and archive the data on network or cloud storage.
  • Data retrieval: To facilitate quick data analysis over any period, the DAQ software must be able to quickly retrieve the data back from network or cloud storage. The storage formats must support random access.
  • Data export: Similarly, it must enable the export of any arbitrary segment of measured data to popular tools like MATLAB, Microsoft Word, and Microsoft Excel.

How should data acquisition software integrate with operating systems and other software?

Since DAQ systems are used in diverse ways — inside the lab, on the production floor, or out in the field — good DAQ software must have the following flexibility features:

  • Enable use from mobile devices: Many companies use tablets to monitor tests because they’re easier to move around than laptops. DAQ software must integrate with such mobile devices. For example, engineers can install the BenchVue Mobile app on an Android or iOS device to control BenchVue applications.
  • Support various operating systems: DAQ software must offer compatibility with major operating systems like Windows, Linux, and macOS.
  • Support programmatic access: Programmatic access to DAQ systems must be available so that DAQ systems can be accessed and monitored from other platforms like MATLAB, programming languages like Python, or custom data acquisition software. For example, the IO Libraries Suite enables other systems to supervise DAQ systems and other instruments.

What security measures are implemented in data acquisition software?

Data acquisition systems and DAQ software are extensively used in strategic sectors like defense, aerospace and avionics, satellites, space systems, semiconductors, automobiles, and health care. All these face high risks of espionage, sabotage, backdoor attacks, and data theft by enemy intelligence agencies, hackers, targeted malware, and even business competitors.

Two examples of possible attacks on sensitive equipment, with DAQ as a vector, are described below:

  1. Since DAQ software connects to DAQ systems via LAN or USB, enemy intelligence agencies can exploit network or system vulnerabilities to find out the performance and operational characteristics of sensitive defense components like radars.
  2. During production testing of firmware chips that go into sensitive defense equipment, targeted malware can use DAQ systems that connect to their pins to inject code that makes the equipment malfunction during operation.

To prevent such possibilities, below are some security measures that must be implemented by DAQ software:

  • Authentication and access control: Access to data acquisition software and systems must be protected by strong authentication methods, instrument certificates, and centralized authorization.
  • Secured network transmissions: DAQ software that supports secure network protocols like the high-speed LAN instrument protocol (HiSLIP) must be used.
  • Data encryption: The measurement data on storage media and in memory must be encrypted.
  • Data hashing: Use techniques like data hashing during measurements to ensure non-repudiation of the data.
  • Audit logs: Maintain audit logs of all actions and events that occurred during a test.

TestEquity are an approved UK partner for Keysight
Data Acquisition Software: The Brains Behind the Hardware
Content Source: https://www.keysight.com/blogs/en/tech/educ/2024/data-acquisition-software