Industrial Data Acquisition Application Case Study

Industrial Data Acquisition Applications

PXI DAQ System for Automotive Component Testing

Customer Case

The customer supplies sub-assembly products to many industries, including automotive, communications, industrial, aerospace/defense and computer. The customer's specific automotive component testing application systems are used throughout the world for testing component level assemblies for automobiles.

There are numerous test stands that are used for automotive sub-assembly development and testing. The customer designs, develops and tests the components based on their customers' criteria. The testing process involves many temperature controlled test chambers to simulate worst case component environments. A majority of the test stands include an environmental chamber in which the article under test is placed. Some test stands are set to sustain a fixed temperature while others are configured to cycle through a pre-defined temperature profile.

During the component testing process, the sub-assemblies are mechanically cycled 24 hours a day, 7 days a week for up to several months. During the mechanical cycle time, the data acquistion system records the position and monitors the motion profile to ensure the pedal is performing as designed. In some instances stress is also measured on the component under test.

There are several types of data acquisition systems deployed at the facility. Three of the systems are already KineticSystems VXI hardware based and the remainder are a mix of older technology non-standards based platforms.

The front-end of the data acquisition systems is a custom solution developed in-house. Since each of their customers (and specific product) require unique testing and cycling parameters, they developed a re-configurable chassis that provides various loads to the component assembly electronics. This front-end load control box is then configured according to the manufacturers testing protocol.

Following the custom front-end is the data acquisition system. The KineticSystems VXI data acquisition systems contain a V207 16-bit analog-to-digital converter preceded by several V253 programmable gain and filter signal conditioners. The V253s are outfitted with the sample and hold options so that simultaneous sampling can be employed. Simultaneous sampling is required for this application due to the correlation that is used to verify channel-to-channel profiling for the article under test. The total channel count of a system was up to 32 channels, even though not all channels were used during a collection process.

The software used to control the system is written in LabVIEW. There are several different applications that are used based on the type of article under test, but the basic analysis is the same for most tests. The test results are logged to a database for analysis and archival purposes.

The customer's requirements for the new data acquisition system were as follows:

  • Low cost as possible; at least lower cost than VXI solution.
  • Provide equal or better data quality than present VXI system. They are very satisfied with the quality of data that they are receiving with the VXI system and did NOT want any lesser quality.
  • Modern software APIs (Application Programming Interfaces) with advanced functionality to minimize programming effort.
  • LabVIEW support.
  • Ability to perform ad-hoc data acquisition exercises without having to write any code.
  • Perform in-house periodic calibration.
  • Simultaneous sampling of analog input signals.
  • Programmable filter.
  • Programmable gain. However, most channels use signal voltage levels of ±10 volts.
  • Minimum 24 channels.
  • Sample rate per channel of 100 Hz to 1 kHz. Would like higher sampling rates to allow for other future testing requirements.

The overall goal for the new implementations for the data acquisition systems was overall cost and performance. Cost not only included the hardware cost, but also the cost associated with the in-house development of the application software. Also, the resultant system had to be turn-key so that others could easily be trained to use the system. In the past, they had many versions of data acquisition hardware and software applications. This made it extremely difficult to deploy and maintain systems in other countries.

The first system to be developed is to be used in China. After the initial development and testing is complete, an additional system is to be purchased for use in the Indiana facility.

There were five data acquisition providers in competition for the system that included DynamicSignals - KineticSystems, National Instruments, IOTech, HBM and Data Translation.

KineticSystems Case Solution

KineticSystems developed a small PXI based portable system in a chassis consisting of an embedded processor with a CP246 module. The latest versions of the Plug and Play (PNP) drivers were installed, including application examples, and SoftView. SoftView has been a very valuable tool to demonstrate the full flexibility of the hardware and the completeness of software support.

KineticSystems then demonstrated the system and its capabilities to the customer. The product demonstration included basic instrument setup, recording to disk, post-processing, documentation and the per-channel expression entry (virtual channel) feature. The customer was impressed with the ease at which a test could be configured and executed using SoftView. Although SoftView would not be their primary data acquisition software solution, it came pretty close with its ease of use capabilities. The final application would utilize many of the important capabilities of the API that SoftView exposes, but the user interface would be simplified in the turn-key package. This would minimize any confusion in configuring and running tests.

A few of the key points that SoftView demonstrated for the customer's application included the on-line documentation, the fully featured API and the virtual channel feature (utilizing the formula engine).

The customer found great value in the on-line documentation implementation in SoftView. When running SoftView, a Help screen can be requested for any feature exposed. From this Help screen, the user can see the requisite API function call necessary to setup the specific operating parameter. This minimizes the amount of time one has to "hunt" through user documentation to discover the API call required.

Included with all the KineticSystems PXI products is the stream library. The stream library is an API library that manages the data transfer flow to and from an instrument. The library allows one to monitor the data flow, extract elements of the data stream, create intelligent formula streams (virtual channels) and store data directly to disk.

The customer felt that these features are extremely beneficial and that their system would be easier to implement with this capability. Streaming data directly to disk would avoid them having to write the code to perform this function, as it is already available in the standard API.

The virtual channel stream is another huge benefit for their application. A major requirement for their system is simultaneous sampling for channel-to-channel correlation. They use the correlation to ensure that the article under test meets the testing profile. The customer will use the formula engine of the stream library to create a virtual channel that will be the correlation of two analog input channels. Then, the application can monitor this correlation channel without having to perform any calculation in the application code.

In order to generate the correlation channel(s) a formula engine is created using the stream library. The mathematical equation is defined for the "new" virtual channel that is the correlation of two other (or more) channels. Once the data acquisition process is started, the virtual channel can be analyzed in real-time as any other true input would. As well, the formula engine can be re-invoked during post-processing to get a post-processed view of the virtual channel.

SoftView again proved to be a huge enabling technology to demonstrate the feature of both the hardware and the accompanying software APIs. Additionally, the application examples were beneficial in demonstrating hardware access through LabWindows/CVI and LabVIEW. There was also mention of using SoftView as the data acquisition software when ad-hoc experimentation was required. Data could be collected using SoftView and analyzed by the same application program that the final system would utilize.

The KineticSystems demonstration proved to be a success. All were impressed with the capabilities of the hardware and software. From the customer's comments at the end of the demonstration it was indicated that this would be a good solution for their data acquisition requirement. The system would be easier to implement than systems in the past due to the highly integrated software support.

As a result of the successful demonstration at the Indiana facility, we received an order for the first of two systems. The first system consisted of 24 channels with extra slot capacity so that the system could easily be upgraded to 32 channels in the future by just adding one CP246 card. This 24-channel system is to be the development system that will eventually make its way to China. The second system, consisting of 40 channels, will be deployed in the Indiana facility. Both systems have been delivered. Additional systems will be required as development concludes on the first two and they are put to use in the field.

For this automotive testing application we had all the necessary requirements covered between our hardware and software solution, with one exception. The customer wanted to perform in-house periodic calibration of the hardware. A majority of our customers would just as well send their instruments back to the factory for annual calibration. However, they wanted to perform more frequent calibration and wanted to minimize downtime and expense during the calibration process.

In order to provide the ability to perform in-house calibration, we extracted some software that is used during manufacturing test of the CP246. Since the customer does not have all the calibration standards and sources that we utilize during our validation process, additional code was written to support manual entry of the calibration information. The code was written in LabWindows/CVI and supplied for a nominal fee. Along with the supplied calibration software, we hosted an in-house software development training day at our KineticSystems Lockport, IL facility. This training proved to be a time saver for all involved. It minimized the phone support activities and gave us a chance to know and appreciate our customer's needs even better.

KineticSystems Case Recommended Products

The primary KineticSystems products used in this application are:

  • SoftView - Single Integrated Software Package for all cPCI/PXI Instruments with No Programming Required
  • CP246 - cPCI/PXI 16-Bit ADC Bridge Signal Conditioner Module

Industrial Application Request

We encourage you to contact us and discuss your industrial application in more detail with our engineering team. KineticSystems can provide tailored custom data acquisition hardware and software solutions to meet specific industrial application requirements.